Laser-based structural sensing and surface damage detection

Science.gov (United States)

Guldur, Burcu

Damage due to age or accumulated damage from hazards on existing structures poses a worldwide problem. In order to evaluate the current status of aging, deteriorating and damaged structures, it is vital to accurately assess the present conditions. It is possible to capture the in situ condition of structures by using laser scanners that create dense three-dimensional point clouds. This research investigates the use of high resolution three-dimensional terrestrial laser scanners with image capturing abilities as tools to capture geometric range data of complex scenes for structural engineering applications. Laser scanning technology is continuously improving, with commonly available scanners now capturing over 1,000,000 texture-mapped points per second with an accuracy of ~2 mm. However, automatically extracting meaningful information from point clouds remains a challenge, and the current state-of-the-art requires significant user interaction. The first objective of this research is to use widely accepted point cloud processing steps such as registration, feature extraction, segmentation, surface fitting and object detection to divide laser scanner data into meaningful object clusters and then apply several damage detection methods to these clusters. This required establishing a process for extracting important information from raw laser-scanned data sets such as the location, orientation and size of objects in a scanned region, and location of damaged regions on a structure. For this purpose, first a methodology for processing range data to identify objects in a scene is presented and then, once the objects from model library are correctly detected and fitted into the captured point cloud, these fitted objects are compared with the as-is point cloud of the investigated object to locate defects on the structure. The algorithms are demonstrated on synthetic scenes and validated on range data collected from test specimens and test-bed bridges. The second objective of

Surface damage through grazing incidence ions investigated by scanning tunneling microscopy

International Nuclear Information System (INIS)

Redinger, Alex

2009-01-01

Surface damage, caused by grazing incidence ions, is investigated with variable temperature scanning tunneling microscopy. The experiments are carried out on a Pt(111) crystal. The kinetic energy of noble gas ions is varied between 1-15 keV and the angle of incidence can be adjusted between θ = 78.5 and θ = 90 measured with respect to the surface normal. The damage patterns of single ion impacts, on flat terraces and at step edges of monoatomic height, are investigated at low surface temperatures. Ions hitting a flat terrace are usually specular reflected. The energy transfer from the ion to the crystal atoms is small and only little damage is produced. In contrast, at ascending step edges, which are illuminated by the ion beam, large angle scattering events occur. Sputtering, adatom and vacancy production is induced. However, a significant fraction of the ions, which hit step edges, enter the crystal and are guided in between two atomic layers parallel to the surface via small angle binary collisions. This steering process is denoted as subsurface channeling. The energy loss per length scale of the channeled particles is low, which results in long ion trajectories (up to 1000A). During the steering process, the ions produce surface damage. Depending on the ion species and the ion energy, adatom and vacancies or surface vacancy trenches of monoatomic width are observed. The surface damage can be used to track the path of the ion. This makes the whole trajectory of single ions with keV energy visible. The number of sputtered atoms per incident ion at ascending step edges, i.e. the step edge sputtering yield, is measured experimentally for different irradiation conditions. For θ = 86 , the sputtering yield is determined from the fluence dependent retraction of pre-existing illuminated step edges. An alternative method for the step edge sputtering yield determination, is the analysis of the concentration of ascending steps and of the removed amount of material as a

Surface damage through grazing incidence ions investigated by scanning tunneling microscopy

Energy Technology Data Exchange (ETDEWEB)

Redinger, Alex

2009-07-10

Surface damage, caused by grazing incidence ions, is investigated with variable temperature scanning tunneling microscopy. The experiments are carried out on a Pt(111) crystal. The kinetic energy of noble gas ions is varied between 1-15 keV and the angle of incidence can be adjusted between {theta} = 78.5 and {theta} = 90 measured with respect to the surface normal. The damage patterns of single ion impacts, on flat terraces and at step edges of monoatomic height, are investigated at low surface temperatures. Ions hitting a flat terrace are usually specular reflected. The energy transfer from the ion to the crystal atoms is small and only little damage is produced. In contrast, at ascending step edges, which are illuminated by the ion beam, large angle scattering events occur. Sputtering, adatom and vacancy production is induced. However, a significant fraction of the ions, which hit step edges, enter the crystal and are guided in between two atomic layers parallel to the surface via small angle binary collisions. This steering process is denoted as subsurface channeling. The energy loss per length scale of the channeled particles is low, which results in long ion trajectories (up to 1000A). During the steering process, the ions produce surface damage. Depending on the ion species and the ion energy, adatom and vacancies or surface vacancy trenches of monoatomic width are observed. The surface damage can be used to track the path of the ion. This makes the whole trajectory of single ions with keV energy visible. The number of sputtered atoms per incident ion at ascending step edges, i.e. the step edge sputtering yield, is measured experimentally for different irradiation conditions. For {theta} = 86 , the sputtering yield is determined from the fluence dependent retraction of pre-existing illuminated step edges. An alternative method for the step edge sputtering yield determination, is the analysis of the concentration of ascending steps and of the removed amount

NDE of Damage in Aircraft Flight Control Surfaces

International Nuclear Information System (INIS)

Hsu, David K.; Barnard, Daniel J.; Dayal, Vinay

2007-01-01

Flight control surfaces on an aircraft, such as ailerons, flaps, spoilers and rudders, are typically adhesively bonded composite or aluminum honeycomb sandwich structures. These components can suffer from damage caused by hail stone, runway debris, or dropped tools during maintenance. On composites, low velocity impact damages can escape visual inspection, whereas on aluminum honeycomb sandwich, budding failure of the honeycomb core may or may not be accompanied by a disbond. This paper reports a study of the damage morphology in such structures and the NDE methods for detecting and characterizing them. Impact damages or overload failures in composite sandwiches with Nomex or fiberglass core tend to be a fracture or crinkle or the honeycomb cell wall located a distance below the facesheet-to-core bondline. The damage in aluminum honeycomb is usually a buckling failure, propagating from the top skin downward. The NDE methods used in this work for mapping out these damages were: air-coupled ultrasonic scan, and imaging by computer aided tap tester. Representative results obtained from the field will be shown

Surface-structure dependence of healing radiation-damage mechanism in nanoporous tungsten

Science.gov (United States)

Duan, Guohua; Li, Xiangyan; Sun, Jingjing; Hao, Congyu; Xu, Yichun; Zhang, Yange; Liu, Wei; Liu, C. S.

2018-01-01

Under nuclear fusion environments, displacement damage in tungsten (W) is usually caused by neutrons irradiation through producing large quantities of vacancies (Vs) and self-interstitial atoms (SIAs). These defects not only affect the mechanical properties of W, but also act as the trap sites for implanted hydrogen isotopes and helium. Nano-porous (NP) W with a high fraction of free surfaces has been developed to mitigate the radiation damage. However, the mechanism of the surface reducing defects accumulation is not well understood. By using multi-scale simulation methods, we investigated the interaction of the SIA and V with different surfaces on across length and time scales. We found that, at a typical operation temperature of 1000 K, surface (1 1 0) preferentially heals radiation damage of W compared with surface (1 0 0) and boundary (3 1 0). On surface (1 1 0), the diffusion barrier for the SIA is only 0.68 eV. The annihilation of the SIA-V happens via the coupled motion of the V segregation towards the surface from the bulk and the two-dimensional diffusion of the SIA on the surface. Such mechanism makes the surface (1 1 0) owe better healing capability. On surface (1 0 0), the diffusion energy barrier for the SIA is 2.48 eV, higher than the diffusion energy barrier of the V in bulk. The annihilation of the SIA-V occurs via the V segregation and recombination. The SIA was found to migrate one-dimensionally along a boundary (3 1 0) with a barrier of 0.21 eV, leading to a lower healing efficiency in the boundary. This study suggested that the on-surface process plays an important role in healing radiation damage of NP W in addition to surface-enhanced diffusion and annihilation near the surface. A certain surface structure renders nano-structured W more radiation-tolerant.

Characterization of the damage produced on different materials surfaces

International Nuclear Information System (INIS)

Dellavale Clara, Hector Damian

2004-01-01

In the present work the characterization techniques of surfaces ULOI and RIMAPS have been applied on laboratory samples made from aluminium, stainless steel and material based on fiberglass.The resultant surfaces of, chemical etching with corrosive agents Keller and Tucker, mechanic damage from the wear and tear of abrasive paper and sandrubbing with alumina particles, are analyzed to different level of damage.The systematic application of the above mentioned techniques is carried out with the objective of finding information, which allows to characterize the superficial damage, both in its incipient state as in the extreme situation revealed by the presence of etch pits. Important results have been obtained, in the characterization of the incipient stage of the chemical etching, using the curves of the normalized area.In addition, it was possible to verify the capacity of the techniques in the early detection of the preferential directions generated by the etch pits

Time-resolved imaging of filamentary damage on the exit surface of fused silica induced by 1064 nm nanosecond laser pulse

International Nuclear Information System (INIS)

Chao, Shen; Xiang’ai, Cheng; Tian, Jiang; Zhiwu, Zhu; Yifan, Dai

2015-01-01

Laser-induced damage on the exit surface of fused silica with a filament was observed. The filament has a central hollow core surrounded by molten materials and no obvious cracks could be observed. The critical intensity for the transition from pure surface damage (SD) to filamentary damage (FD) was measured. Time-resolved shadowgraphic microscopy with nanosecond time resolution was employed to compare the propagation of shock wave and material response in the SD and FD process. The main different features during the material response process include: (i) thermoelastic shock waves launched in FD were multiple and a column envelope was observed in the lateral direction; (ii) more energy is deposited in the bulk for FD resulting to a lower speed of shock wave in air; (iii) the overall time for establishing the main character of the damage site for FD was shorter because of the absence of crack expansion. Self-focusing and temperature-activated optical absorption enhancement of the bulk material are discussed to explain the morphology difference between SD and FD and the evolution of filament length under different incident intensities. (paper)

Surface/subsurface observation and removal mechanisms of ground reaction bonded silicon carbide

Science.gov (United States)

Yao, Wang; Zhang, Yu-Min; Han, Jie-cai; Zhang, Yun-long; Zhang, Jian-han; Zhou, Yu-feng; Han, Yuan-yuan

2006-01-01

Reaction Bonded Silicon Carbide (RBSiC) has long been recognized as a promising material for optical applications because of its unique combination of favorable properties and low-cost fabrication. Grinding of silicon carbide is difficult because of its high hardness and brittleness. Grinding often induces surface and subsurface damage, residual stress and other types of damage, which have great influence on the ceramic components for optical application. In this paper, surface integrity, subsurface damage and material removal mechanisms of RBSiC ground using diamond grinding wheel on creep-feed surface grinding machine are investigated. The surface and subsurface are studied with scanning electron microscopy (SEM) and optical microscopy. The effects of grinding conditions on surface and subsurface damage are discussed. This research links the surface roughness, surface and subsurface cracks to grinding parameters and provides valuable insights into the material removal mechanism and the dependence of grind induced damage on grinding conditions.

High-flux He+ irradiation effects on surface damages of tungsten under ITER relevant conditions

International Nuclear Information System (INIS)

Liu, Lu; Liu, Dongping; Hong, Yi; Fan, Hongyu; Ni, Weiyuan; Yang, Qi; Bi, Zhenhua; Benstetter, Günther; Li, Shouzhe

2016-01-01

A large-power inductively coupled plasma source was designed to perform the continuous helium ions (He + ) irradiations of polycrystalline tungsten (W) under International Thermonuclear Experimental Reactor (ITER) relevant conditions. He + irradiations were performed at He + fluxes of 2.3 × 10 21 –1.6 × 10 22 /m 2  s and He + energies of 12–220 eV. Surface damages and microstructures of irradiated W were observed by scanning electron microscopy. This study showed the growth of nano-fuzzes with their lengths of 1.3–2.0 μm at He + energies of >70 eV or He + fluxes of >1.3 × 10 22 /m 2  s. Nanometer-sized defects or columnar microstructures were formed in W surface layer due to low-energy He + irradiations at an elevated temperature (>1300 K). The diffusion and coalescence of He atoms in W surface layers led to the growth and structures of nano-fuzzes. This study indicated that a reduction of He + energy below 12–30 eV may greatly decrease the surface damage of tungsten diverter in the fusion reactor.

Assessment of damage to the desert surfaces of Kuwait due to the Gulf War

International Nuclear Information System (INIS)

El-Baz, F.; Al-Ajmi, D.

1993-01-01

This is a preliminary report on a joint research project by Boston University and the Kuwait Institute for Scientific Research that commenced in April 1992. The project aim is to establish the extent and nature of environmental damage to the desert surface and coastal zone of Kuwait due to the Gulf War and its aftermath. Change detection image enhancement techniques were employed to enhance environmental change by comparison of Landsat Thematic Mapper images obtained before the wars and after the cessation of the oil and well fires. Higher resolution SPOT images were also utilized to evaluate the nature of the environmental damage to specific areas. The most prominent changes were due to: (1) the deposition of oil and course-grained soot on the desert surface as a result of ''oil rain'' from the plume that emanated from the oil well fires; (2) the formation of hundreds of oil lakes, from oil seepage at the damaged oil well heads; (3) the mobilization of sand and dust and (4) the pollution of segments of the coastal zone by the deposition of oil from several oil spills. Interpretation of satellite image data are checked in the field to confirm the observations, and to assess the nature of the damage. Final results will be utilized in establishing the needs for remedial action to counteract the harmful effects of the various types of damage to the environment of Kuwait

Cuticular surface damage of Ascaridia galli adult worms treated with Veitchia merrillii betel nuts extract in vitro.

Science.gov (United States)

Balqis, Ummu; Hambal, Muhammad; Rinidar; Athaillah, Farida; Ismail; Azhar; Vanda, Henni; Darmawi

2017-07-01

The objective of this research was to in vitro evaluate the cuticular surface damage of Ascaridia galli adult worms treated with ethanolic extract of betel nuts Veitchia merrillii . Phytochemical screening was done using FeCl 3 , Wagner and Dragendorff reagents, NaOH, MgHCl, and Liebermann-Burchard reaction test. Amount of 16 worms were segregated into four groups with three replicates. Four worms of each group submerged into phosphate buffered saline, 25 mg/ml, and 75 mg/ml crude ethanolic extract of V. merrillii , and 15 mg/ml albendazole. The effect of these extract was observed 40 h after incubation as soon as worms death. The worms were sectioned transversally and were explored for any cuticular histopathological changes in their body surface under microscope. We found that the ethanolic extract of V. merrillii betel nuts contains tannins, alkaloids, flavonoids, triterpenoids, and saponins. The ethanolic extract of betel nuts V. merrillii induces surface alterations caused cuticular damage of A. galli adult worms. We concluded that ethanolic extract of betel nuts V. merrillii possess anthelmintic activity caused cuticular damage of A. galli adult worms.

Examination of observed and predicted measures of creep cavitation damage accumulation

Energy Technology Data Exchange (ETDEWEB)

Brear, J M; Church, J M [ERA Technology Ltd., Leatherhead (United Kingdom); Eggeler, G [University of Bochum-Ruhr (Germany)

1999-12-31

Brittle intergranular cavitation represents a primary degradation mechanism for high temperature plant operating within the creep range. Fundamental to formulating estimates of remanent life, or consumed life fraction for such components are: the observation and quantification of the level of actual creep cavitation, typically using an A-parameter type approach, and the correlation of observed creep damage accumulation with some phenomenological model which characterizes the rate of damage evolution and, thereby, rupture lifetime. The work described here treats inhomogeneous damage accumulation - in otherwise uniform material and loading situations. Extensions to the A-parameter are considered as a practical measure of damage localization and an extension of the Kachanov-Rabotnov continuum damage mechanics model is proposed to allow theoretical treatment. (orig.) 4 refs.

Examination of observed and predicted measures of creep cavitation damage accumulation

Energy Technology Data Exchange (ETDEWEB)

Brear, J.M.; Church, J.M. [ERA Technology Ltd., Leatherhead (United Kingdom); Eggeler, G. [University of Bochum-Ruhr (Germany)

1998-12-31

Brittle intergranular cavitation represents a primary degradation mechanism for high temperature plant operating within the creep range. Fundamental to formulating estimates of remanent life, or consumed life fraction for such components are: the observation and quantification of the level of actual creep cavitation, typically using an A-parameter type approach, and the correlation of observed creep damage accumulation with some phenomenological model which characterizes the rate of damage evolution and, thereby, rupture lifetime. The work described here treats inhomogeneous damage accumulation - in otherwise uniform material and loading situations. Extensions to the A-parameter are considered as a practical measure of damage localization and an extension of the Kachanov-Rabotnov continuum damage mechanics model is proposed to allow theoretical treatment. (orig.) 4 refs.

Automated analysis of damages for radiation in plastics surfaces

International Nuclear Information System (INIS)

Andrade, C.; Camacho M, E.; Tavera, L.; Balcazar, M.

1990-02-01

Analysis of damages done by the radiation in a polymer characterized by optic properties of polished surfaces, of uniformity and chemical resistance that the acrylic; resistant until the 150 centigrade grades of temperature, and with an approximate weight of half of the glass. An objective of this work is the development of a method that analyze in automated form the superficial damages induced by radiation in plastic materials means an images analyst. (Author)

Low energy Ar ion bombardment damage of Si, GaAs, and InP surfaces

International Nuclear Information System (INIS)

Williams, R.S.

1982-01-01

Argon bombardment damage to (100) surfaces of Si, GaAs, and InP for sputter ion-gun potentials of 1, 2, and 3 kilovolts was studied using Rutherford backscattering. Initial damage rates and saturation damage levels were determined. Bombardment damage sensitivity increased for the sequence Si, GaAs, and InP. Saturation damage levels for Si and GaAs correspond reasonably to LSS projected range plus standard deviation estimates; damage to InP exceeded this level significantly. For an ion-gun potential of 3 keV, the initial sputter yield of P from an InP surface exceeded the sputter yield of In by four atoms per incident Ar projectile. (author)

Damage Mechanism in Counter Pairs Caused by Bionic Non-smoothed Surface

Directory of Open Access Journals (Sweden)

ZHANG Zhan-hui

2016-08-01

Full Text Available Four biomimetic non-smoothed surface specimens with different shapes were prepared by laser processing. Tests were conducted on MMU-5G wear and abrasion test machine to study the influencing rule of non-smoothed surfaces on counter pairs. The results show that the mass loss of the friction pair matching with the non-smoothed units is much greater than the ones matching with the smooth specimens. The pairs matching with different non-smoothed units suffer differently. The non-smoothed surface protruding zone exerts micro cutting on counter pairs. The striation causes the greatest mass loss of the pairs than the other non-smoothed units, which almost doubles the damage of the grid ones suffering the least. The difference in pairs damage is attributed to the different mechanism of undertaking the load in the process of wear. The damage can be alleviated effectively by changing the shapes of the units without increasing or decreasing the area ratio of the non-smoothed units.

Failure modes observed on worn surfaces of W-C-Co sputtered coatings

International Nuclear Information System (INIS)

Ramalho, A.; Cavaleiro, A.; Miranda, A.S.; Vieira, M.T.

1993-01-01

During scratch testing, the indenter gives rise to a distribution of stresses similar to that observed in tribocontacts. In this work, r.f.-sputtered W-C-Co coatings deposited from sintered WC + Co (6, 10 and 15 wt.% Co) at various substrate biases were scratched and tested tribologically and the morphology of the damaged surfaces was analysed. The cobalt content of the coatings is the main factor determining their tribological characteristics. The failure modes observed on the worn pin-on-disc tested surfaces are explained and compared with those obtained by scratch testing. In spite of it not being possible to establish quantitative results for the wear resistance of W-C-Co coatings from scratch testing, an estimation can be performed based on the observation of the failure modes in the scratch track. Thus scratch testing can be used to predict the tribological behaviour of coated surfaces. This possibility can reduce the number and cost of tribological tests. (orig.)

Hydroxyapatite coating on damaged tooth surfaces by immersion

International Nuclear Information System (INIS)

Lim, Byoung-Ki; Ryu, Su-Chak; Sun, Fangfang; Koh, Kwangnak; Han, Dong-Wook; Lee, Jaebeom

2009-01-01

Hydroxyapatite (HAp) was coated on scratched areas of a human tooth and HAp disks by the immersion method in a HAp colloidal solution (≤20 μm of average diameter dispersed in DI water). The surface morphologies of the scratched area after immersion for 1-3 months were investigated showing that the damaged surfaces were remarkably recovered. Then, the mechanical property and chemical stability of the HAp coating layers on both specimens were determined via the Vickers hardness test and concentration measurement of extracted Ca 2+ ions, respectively, after strong acidic treatment. The cellular behavior of mouse calvaria-derived pre-osteoblastic cells (MC3T3-E1) was also examined on the HAp layers regenerated on micro-scratched HAp disks for the purpose of their potential applications on maxillofacial bone conservation and reconstruction for prosthetic dentistry, and artificial disk preparation of a vertebral column. The notable loss of Ca 2+ ions under a highly acidic condition was not observed in the layers coated by HAp adsorption, indicating that the coating surface was well adhered with the original surfaces of the respective specimen. Moreover, the HAp adsorption did not adversely affect the adhesion, growth and proliferation of MC3T3-E1 cells on the coated HAp layers for up to 21 days. These results suggest that the HAp coating on the scratched areas of the tooth would be effectively applicable for the development of long-term prevention of micro-cleavage and tooth health supporters to reduce discoloration and further maxillofacial and orthopedic applications.

Noninvasive assessment of articular cartilage surface damage using reflected polarized light microscopy

Science.gov (United States)

Huynh, Ruby N.; Nehmetallah, George; Raub, Christopher B.

2017-06-01

Articular surface damage occurs to cartilage during normal aging, osteoarthritis, and in trauma. A noninvasive assessment of cartilage microstructural alterations is useful for studies involving cartilage explants. This study evaluates polarized reflectance microscopy as a tool to assess surface damage to cartilage explants caused by mechanical scraping and enzymatic degradation. Adult bovine articular cartilage explants were scraped, incubated in collagenase, or underwent scrape and collagenase treatments. In an additional experiment, cartilage explants were subject to scrapes at graduated levels of severity. Polarized reflectance parameters were compared with India ink surface staining, features of histological sections, changes in explant wet weight and thickness, and chondrocyte viability. The polarized reflectance signal was sensitive to surface scrape damage and revealed individual scrape features consistent with India ink marks. Following surface treatments, the reflectance contrast parameter was elevated and correlated with image area fraction of India ink. After extensive scraping, polarized reflectance contrast and chondrocyte viability were lower than that from untreated explants. As part of this work, a mathematical model was developed and confirmed the trend in the reflectance signal due to changes in surface scattering and subsurface birefringence. These results demonstrate the effectiveness of polarized reflectance microscopy to sensitively assess surface microstructural alterations in articular cartilage explants.

Surface Damage and Treatment by Impact of a Low Temperature Nitrogen Jet

Science.gov (United States)

Laribou, Hicham; Fressengeas, Claude; Entemeyer, Denis; Jeanclaude, Véronique; Tazibt, Abdel

2011-01-01

Nitrogen jets under high pressure and low temperature have been introduced recently. The process consists in projecting onto a surface a low temperature jet obtained from releasing the liquid nitrogen stored in a high pressure tank (e.g. 3000 bars) through a nozzle. It can be used in a range of industrial applications, including surface treatment or material removal through cutting, drilling, striping and cleaning. The process does not generate waste other than the removed matter, and it only releases neutral gas into the atmosphere. This work is aimed at understanding the mechanisms of the interaction between the jet and the material surface. Depending on the impacted material, the thermo-mechanical shock and blast effect induced by the jet can activate a wide range of damage mechanisms, including cleavage, crack nucleation and spalling, as well as void expansion and localized ductile failure. The test parameters (standoff distance, dwell time, operating pressure) play a role in selecting the dominant damage mechanism, but combinations of these various modes are usually present. Surface treatment through phase transformation or grain fragmentation in a layer below the surface can also be obtained by adequate tuning of the process parameters. In the current study, work is undertaken to map the damage mechanisms in metallic materials as well as the influence of the test parameters on damage, along with measurements of the thermo-mechanical conditions (impact force, temperature) in the impacted area.

Molecular dynamics simulation of temperature effects on low energy near-surface cascades and surface damage in Cu

Science.gov (United States)

Zhu, Guo; Sun, Jiangping; Guo, Xiongxiong; Zou, Xixi; Zhang, Libin; Gan, Zhiyin

2017-06-01

The temperature effects on near-surface cascades and surface damage in Cu(0 0 1) surface under 500 eV argon ion bombardment were studied using molecular dynamics (MD) method. In present MD model, substrate system was fully relaxed for 1 ns and a read-restart scheme was introduced to save total computation time. The temperature dependence of damage production was calculated. The evolution of near-surface cascades and spatial distribution of adatoms at varying temperature were analyzed and compared. It was found that near-surface vacancies increased with temperature, which was mainly due to the fact that more atoms initially located in top two layers became adatoms with the decrease of surface binding energy. Moreover, with the increase of temperature, displacement cascades altered from channeling-like structure to branching structure, and the length of collision sequence decreased gradually, because a larger portion of energy of primary knock-on atom (PKA) was scattered out of focused chain. Furthermore, increasing temperature reduced the anisotropy of distribution of adatoms, which can be ascribed to that regular registry of surface lattice atoms was changed with the increase of thermal vibration amplitude of surface atoms.

Molecular dynamics simulation of temperature effects on low energy near-surface cascades and surface damage in Cu

Energy Technology Data Exchange (ETDEWEB)

Zhu, Guo; Sun, Jiangping; Guo, Xiongxiong; Zou, Xixi; Zhang, Libin; Gan, Zhiyin, E-mail: ganzhiyin@126.com

2017-06-15

The temperature effects on near-surface cascades and surface damage in Cu(0 0 1) surface under 500 eV argon ion bombardment were studied using molecular dynamics (MD) method. In present MD model, substrate system was fully relaxed for 1 ns and a read-restart scheme was introduced to save total computation time. The temperature dependence of damage production was calculated. The evolution of near-surface cascades and spatial distribution of adatoms at varying temperature were analyzed and compared. It was found that near-surface vacancies increased with temperature, which was mainly due to the fact that more atoms initially located in top two layers became adatoms with the decrease of surface binding energy. Moreover, with the increase of temperature, displacement cascades altered from channeling-like structure to branching structure, and the length of collision sequence decreased gradually, because a larger portion of energy of primary knock-on atom (PKA) was scattered out of focused chain. Furthermore, increasing temperature reduced the anisotropy of distribution of adatoms, which can be ascribed to that regular registry of surface lattice atoms was changed with the increase of thermal vibration amplitude of surface atoms.

Automated 3D Damaged Cavity Model Builder for Lower Surface Acreage Tile on Orbiter

Science.gov (United States)

Belknap, Shannon; Zhang, Michael

2013-01-01

The 3D Automated Thermal Tool for Damaged Acreage Tile Math Model builder was developed to perform quickly and accurately 3D thermal analyses on damaged lower surface acreage tiles and structures beneath the damaged locations on a Space Shuttle Orbiter. The 3D model builder created both TRASYS geometric math models (GMMs) and SINDA thermal math models (TMMs) to simulate an idealized damaged cavity in the damaged tile(s). The GMMs are processed in TRASYS to generate radiation conductors between the surfaces in the cavity. The radiation conductors are inserted into the TMMs, which are processed in SINDA to generate temperature histories for all of the nodes on each layer of the TMM. The invention allows a thermal analyst to create quickly and accurately a 3D model of a damaged lower surface tile on the orbiter. The 3D model builder can generate a GMM and the correspond ing TMM in one or two minutes, with the damaged cavity included in the tile material. A separate program creates a configuration file, which would take a couple of minutes to edit. This configuration file is read by the model builder program to determine the location of the damage, the correct tile type, tile thickness, structure thickness, and SIP thickness of the damage, so that the model builder program can build an accurate model at the specified location. Once the models are built, they are processed by the TRASYS and SINDA.

Surface Irregularity Factor as a Parameter to Evaluate the Fatigue Damage State of CFRP

Directory of Open Access Journals (Sweden)

Pablo Zuluaga-Ramírez

2015-11-01

Full Text Available This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL and realistic variable amplitude loads (VAL, representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications.

Surface Irregularity Factor as a Parameter to Evaluate the Fatigue Damage State of CFRP

Science.gov (United States)

Zuluaga-Ramírez, Pablo; Frövel, Malte; Belenguer, Tomás; Salazar, Félix

2015-01-01

This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL) and realistic variable amplitude loads (VAL), representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications. PMID:28793655

He-ion and self-atom induced damage and surface-morphology changes of a hot W target

International Nuclear Information System (INIS)

Meyer, F W; Hijazi, H; Bannister, M E; Dadras, J; Krstic, P S; Meyer, H M III; Parish, C M

2014-01-01

We report results of measurements on the evolution of the surface morphology of a hot tungsten surface due to impacting low-energy (80–12 000 eV) He ions and of simulations of damage caused by cumulative bombardment of 1 and 10 keV W self-atoms. The measurements were performed at the ORNL Multicharged Ion Research Facility, while the simulations were done at the Kraken supercomputing facility of the University of Tennessee. At 1 keV, the simulations show strong defect-recombination effects that lead to a saturation of the total defect number after a few hundred impacts, while sputtering leads to an imbalance of the vacancy and interstitial number. On the experimental side, surface morphology changes were investigated over a broad range of fluences, energies and temperatures for both virgin and pre-damaged W-targets. At the lowest accumulated fluences, small surface-grain features and near-surface He bubbles are observed. At the largest fluences, individual grain characteristics disappear in focused ion beam/scanning electron microscopy (FIB/SEM) scans, and the entire surface is covered by a multitude of near-surface bubbles with a broad range of sizes, and disordered whisker growth, while in top-down SEM imaging the surface is virtually indistinguishable from the nano-fuzz produced on linear plasma devices. These features are evident at progressively lower fluences as the He-ion energy is increased. (paper)

Effect of electrical discharge machining on surface characteristics and machining damage of AISI D2 tool steel

International Nuclear Information System (INIS)

Guu, Y.H.; Hocheng, H.; Chou, C.Y.; Deng, C.S.

2003-01-01

In this work the electrical discharge machining (EDM) of AISI D2 tool steel was investigated. The surface characteristics and machining damage caused by EDM were studied in terms of machining parameters. Based on the experimental data, an empirical model of the tool steel was also proposed. A new damage variable was used to study the EDM damage. The workpiece surface and re-solidified layers were examined by a scanning electron microscopy. Surface roughness was determined with a surface profilometer. The residual stress acting on the EDM specimen was measured by the X-ray diffraction technique. Experimental results indicate that the thickness of the recast layer, and surface roughness are proportional to the power input. The EDM process introduces tensile residual stress on the machined surface. The EDM damage leads to strength degradation

Cell surface damage and morphological changes in Oenococcus oeni after freeze-drying and incubation in synthetic wine.

Science.gov (United States)

Bravo-Ferrada, Bárbara Mercedes; Gonçalves, Sónia; Semorile, Liliana; Santos, Nuno C; Brizuela, Natalia; Elizabeth Tymczyszyn, E; Hollmann, Axel

2018-04-28

The aim of the present study was to evaluate the effects of freeze-drying in the presence of trehalose as a cryoprotectant, followed by incubation in synthetic wine, on surface damage, viability and l-malic acid consumption of the oenological strain Oenococcus oeni UNQOe 73.2. After freeze-drying, no significant differences were observed in the number of viable cells (for both acclimated and non-acclimated cultures) respect to the fresh culture. In contrast, loss of viability was observed after wine incubation for 24 h, being acclimated freeze-dried cells the best conditions for this. After the preservation process, small changes in cell morphology were observed by Atomic Force Microscopy (AFM). The Zeta potential and AFM showed that 24 h of wine incubation was enough to induce several cell surface modifications. Plate count data allowed us to establish that surface damage is an important factor for loss of viability, regardless of the acclimation treatment. Although the number of surviving O. oeni cells decreased dramatically after incubation in synthetic wine for 15 days, the consumption of l-malic acid was higher than 70%, with freeze-dried cells showing a better performance than fresh cultures. These results demonstrate that O. oeni freeze-dried cultures could be applied to direct wine inoculation, to conduct malolactic fermentation, maintaining its technological properties and reducing the time and costs of the winemaking process. Copyright © 2018. Published by Elsevier Inc.

A Method to Simulate the Observed Surface Properties of Proton Irradiated Silicon Strip Sensors

CERN Document Server

Peltola, Timo Hannu Tapani

2014-01-01

A defect model of Synopsys Sentaurus TCAD simulation package for the bulk properties of proton irradiated devices has been producing simulations closely matching to measurements of silicon strip detectors. However, the model does not provide the expected behavior due to the fluence increased surface damage. The solution requires an approach that does not affect the accurate bulk properties produced by the proton model, but only adds to it the required radiation induced properties close to the surface. These include the observed position dependency of the strip detector's...

Process induced sub-surface damage in mechanically ground silicon wafers

International Nuclear Information System (INIS)

Yang Yu; De Munck, Koen; Teixeira, Ricardo Cotrin; Swinnen, Bart; De Wolf, Ingrid; Verlinden, Bert

2008-01-01

Micro-Raman spectroscopy, scanning electron microcopy, atomic force microscopy and preferential etching were used to characterize the sub-surface damage induced by the rough and fine grinding steps used to make ultra-thin silicon wafers. The roughly and ultra-finely ground silicon wafers were examined on both the machined (1 0 0) planes and the cross-sectional (1 1 0) planes. They reveal similar multi-layer damage structures, consisting of amorphous, plastically deformed and elastically stressed layers. However, the thickness of each layer in the roughly ground sample is much higher than its counterpart layers in the ultra-finely ground sample. The residual stress after rough and ultra-fine grinding is in the range of several hundreds MPa and 30 MPa, respectively. In each case, the top amorphous layer is believed to be the result of sequential phase transformations (Si-I to Si-II to amorphous Si). These phase transformations correspond to a ductile grinding mechanism, which is dominating in ultra-fine grinding. On the other hand, in rough grinding, a mixed mechanism of ductile and brittle grinding causes multi-layer damage and sub-surface cracks

Dry Etch Black Silicon with Low Surface Damage: Effect of Low Capacitively Coupled Plasma Power

DEFF Research Database (Denmark)

Iandolo, Beniamino; Plakhotnyuk, Maksym; Gaudig, Maria

2017-01-01

Black silicon fabricated by reactive ion etch (RIE) is promising for integration into silicon solar cells thanks to its excellent light trapping ability. However, intensive ion bombardment during the RIE induces surface damage, which results in enhanced surface recombination velocity. Here, we pr...... carrier lifetime thanks to reduced ion energy. Surface passivation using atomic layer deposition of Al2O3 improves the effective lifetime to 7.5 ms and 0.8 ms for black silicon n- and p-type wafers, respectively.......Black silicon fabricated by reactive ion etch (RIE) is promising for integration into silicon solar cells thanks to its excellent light trapping ability. However, intensive ion bombardment during the RIE induces surface damage, which results in enhanced surface recombination velocity. Here, we...... present a RIE optimization leading to reduced surface damage while retaining excellent light trapping and low reflectivity. In particular, we demonstrate that the reduction of the capacitively coupled power during reactive ion etching preserves a reflectance below 1% and improves the effective minority...

Damages of surface ozone: evidence from agricultural sector in China

Science.gov (United States)

Yi, Fujin; McCarl, Bruce A.; Zhou, Xun; Jiang, Fei

2018-03-01

This study measures the damages that surface ozone pollution causes within the Chinese agricultural sector under 2014 conditions. It also analyzes the agricultural benefits of ozone reductions. The analysis is done using a partial equilibrium model of China’s agricultural sector. Results indicate that there are substantial, spatially differentiated damages that are greatest in ozone-sensitive crop growing areas with higher ozone concentrations. The estimated damage to China’s agricultural sector range is between CNY 1.6 trillion and 2.2 trillion, which for comparison is about one fifth of 2014 agricultural revenue. When considering concentration reduction we find a 30% ozone reduction yields CNY 678 billion in sectoral benefits. These benefits largely fall to consumers with producers losing as the production gains lead to lower prices.

Measurements and TCAD Simulations of Bulk and Surface Radiation Damage Effects

CERN Document Server

F. Moscatelli; G. M. Bilei; A. Morozzi; G.-F. Dalla Betta; R. Mendicino; M. Boscardin; N. Zorzi; L. Servoli; P. Maccagnani

2016-01-01

In this work we propose the application of a radiation damage model based on the introduction of deep level traps/recombination centers suitable for device level numerical simulation of radiation detectors at very high fluences (e.g. 1÷2×1016 1-MeV equivalent neutrons per square centimeter) combined with a surface damage model developed by using experimental parameters extracted from measurements from gamma irradiated p-type dedicated test structures.

Multi-Dimensional Damage Detection for Surfaces and Structures

Science.gov (United States)

Williams, Martha; Lewis, Mark; Roberson, Luke; Medelius, Pedro; Gibson, Tracy; Parks, Steen; Snyder, Sarah

2013-01-01

Current designs for inflatable or semi-rigidized structures for habitats and space applications use a multiple-layer construction, alternating thin layers with thicker, stronger layers, which produces a layered composite structure that is much better at resisting damage. Even though such composite structures or layered systems are robust, they can still be susceptible to penetration damage. The ability to detect damage to surfaces of inflatable or semi-rigid habitat structures is of great interest to NASA. Damage caused by impacts of foreign objects such as micrometeorites can rupture the shell of these structures, causing loss of critical hardware and/or the life of the crew. While not all impacts will have a catastrophic result, it will be very important to identify and locate areas of the exterior shell that have been damaged by impacts so that repairs (or other provisions) can be made to reduce the probability of shell wall rupture. This disclosure describes a system that will provide real-time data regarding the health of the inflatable shell or rigidized structures, and information related to the location and depth of impact damage. The innovation described here is a method of determining the size, location, and direction of damage in a multilayered structure. In the multi-dimensional damage detection system, layers of two-dimensional thin film detection layers are used to form a layered composite, with non-detection layers separating the detection layers. The non-detection layers may be either thicker or thinner than the detection layers. The thin-film damage detection layers are thin films of materials with a conductive grid or striped pattern. The conductive pattern may be applied by several methods, including printing, plating, sputtering, photolithography, and etching, and can include as many detection layers that are necessary for the structure construction or to afford the detection detail level required. The damage is detected using a detector or

Compression of laminated composite beams with initial damage

Science.gov (United States)

Breivik, Nicole L.; Gurdal, Zafer; Griffin, O. H., Jr.

1993-01-01

The effect of isolated damage modes on the compressive strength and failure characteristics of laminated composite test specimens were evaluated experimentally and numerically. In addition to specimens without initial damage, specimens with three types of initial damage were considered: (1) specimens with short delaminations distributed evenly through the specimen thickness, (2) specimens with few long delaminations, and (3) specimens with local fiber damage in the surface plies under the three-point bend contact point. It was found that specimens with short multiple delamination experienced the greatest reduction in compression strength compared to the undamaged specimens. Single delaminations far from the specimen surface had little effect on the final compression strength, and moderate strength reduction was observed for specimens with localized surface ply damage.

The impact of mechanical log surface damage on chip size ...

African Journals Online (AJOL)

Mechanised harvesting operations are becoming more prevalent in South Africa with the realisation that motormanual and manual harvesting operations pose significant health and safety risks to workers. The damage inflicted by single-grip harvester feed rollers and delimbing knives on log surfaces during debranching ...

Quantitative evaluation for small surface damage based on iterative difference and triangulation of 3D point cloud

Science.gov (United States)

Zhang, Yuyan; Guo, Quanli; Wang, Zhenchun; Yang, Degong

2018-03-01

This paper proposes a non-contact, non-destructive evaluation method for the surface damage of high-speed sliding electrical contact rails. The proposed method establishes a model of damage identification and calculation. A laser scanning system is built to obtain the 3D point cloud data of the rail surface. In order to extract the damage region of the rail surface, the 3D point cloud data are processed using iterative difference, nearest neighbours search and a data registration algorithm. The curvature of the point cloud data in the damage region is mapped to RGB color information, which can directly reflect the change trend of the curvature of the point cloud data in the damage region. The extracted damage region is divided into three prism elements by a method of triangulation. The volume and mass of a single element are calculated by the method of geometric segmentation. Finally, the total volume and mass of the damage region are obtained by the principle of superposition. The proposed method is applied to several typical injuries and the results are discussed. The experimental results show that the algorithm can identify damage shapes and calculate damage mass with milligram precision, which are useful for evaluating the damage in a further research stage.

Surface damage versus defect microstructures in He and H ion co-implanted Si{sub 3}N{sub 4}/Si

Energy Technology Data Exchange (ETDEWEB)

Zhu, F. [School of Science, Tianjin University, Tianjin 300072 (China); Liu, C.L., E-mail: liuchanglong@tju.edu.cn [School of Science, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Institute of Advanced Materials Physics Faculty of Science, Tianjin 300072 (China); Gao, Y.J.; Wang, Z.; Wang, J. [School of Science, Tianjin University, Tianjin 300072 (China)

2012-09-01

Cz n-type Si (1 0 0) wafers with a top Si{sub 3}N{sub 4} layer of about 170 nm in thickness were sequentially implanted with 40 keV He ions at a fluence of 5 Multiplication-Sign 10{sup 16}/cm{sup 2} and 35 keV H ions at fluences of 1 Multiplication-Sign 10{sup 15}, 5 Multiplication-Sign 10{sup 15} and 1 Multiplication-Sign 10{sup 16}/cm{sup 2}, respectively. Creation and evolution of surface damage as well as micro-defects have been studied. Our results clearly show that production of surface damage depends strongly on both the H implant fluence and annealing temperature. Only blistering or localized exfoliation of the top Si{sub 3}N{sub 4} layer has been observed for post H implantation at fluences of 1 Multiplication-Sign 10{sup 15} and 5 Multiplication-Sign 10{sup 15}/cm{sup 2} upon 800 Degree-Sign C annealing. However, serious surface exfoliation has been found for the 1 Multiplication-Sign 10{sup 16}/cm{sup 2} H co-implanted samples after annealing at 450 Degree-Sign C and above. The exfoliation occurs at a depth of about 360 nm from the surface, which is obviously larger than the He or H ion range. Moreover, the exfoliated craters show clear two-step structures. Cross-sectional transmission electron microscopy (XTEM) observations reveal formation of micro-cracks in Si bulk and along the original interface, which is mainly responsible for the observed surface phenomena. The formation mechanism of micro-cracks has been discussed in combination of He and H implant-induced defects, impurities as well as their interactions upon annealing.

Simulating damage for wind storms in the land surface model ORCHIDEE-CAN (revision 4262)

Science.gov (United States)

Chen, Yi-Ying; Gardiner, Barry; Pasztor, Ferenc; Blennow, Kristina; Ryder, James; Valade, Aude; Naudts, Kim; Otto, Juliane; McGrath, Matthew J.; Planque, Carole; Luyssaert, Sebastiaan

2018-03-01

Earth system models (ESMs) are currently the most advanced tools with which to study the interactions among humans, ecosystem productivity, and the climate. The inclusion of storm damage in ESMs has long been hampered by their big-leaf approach, which ignores the canopy structure information that is required for process-based wind-throw modelling. Recently the big-leaf assumptions in the large-scale land surface model ORCHIDEE-CAN were replaced by a three-dimensional description of the canopy structure. This opened the way to the integration of the processes from the small-scale wind damage risk model ForestGALES into ORCHIDEE-CAN. The integration of ForestGALES into ORCHIDEE-CAN required, however, developing numerically efficient solutions to deal with (1) landscape heterogeneity, i.e. account for newly established forest edges for the parameterization of gusts; (2) downscaling spatially and temporally aggregated wind fields to obtain more realistic wind speeds that would represents gusts; and (3) downscaling storm damage within the 2500 km2 pixels of ORCHIDEE-CAN. This new version of ORCHIDEE-CAN was parameterized over Sweden. Subsequently, the performance of the model was tested against data for historical storms in southern Sweden between 1951 and 2010 and south-western France in 2009. In years without big storms, here defined as a storm damaging less than 15 × 106 m3 of wood in Sweden, the model error is 1.62 × 106 m3, which is about 100 % of the observed damage. For years with big storms, such as Gudrun in 2005, the model error increased to 5.05 × 106 m3, which is between 10 and 50 % of the observed damage. When the same model parameters were used over France, the model reproduced a decrease in leaf area index and an increase in albedo, in accordance with SPOT-VGT and MODIS records following the passing of Cyclone Klaus in 2009. The current version of ORCHIDEE-CAN (revision 4262) is therefore expected to have the capability to capture the dynamics of

Lack of correlation between villus and crypt damage in irradiated mouse intestine

International Nuclear Information System (INIS)

Carr, K.E.; Hamlet, R.; Nias, A.H.W.; Watt, C.

1979-01-01

It has been observed that scanning electron microscopy is a more sensitive indicator of mucosal damage at low radiation dose levels than conventional quantitative crypt counting techniques. Three different fractionation schedules were subjected to investigation by both of these methods to try and elucidate some features of irradiation damage to the whole of the intestinal mucosa, at dose levels commonly used in clinical practice. Despite variations in the qualitative observations, there was a marked difference in two of the schedules between damage expressed as crypt counts and that described by the qualitative techniques. In the first case high crypt numbers were associated with severe mucosal damage, whereas the second schedule produced a reduced crypt count in association with low damage to the surface mucosa. A third schedule produced results in which there was a general agreement between low crypt numbers and considerable surface mucosal damage. However, observations were made of mucosal formations not previously seen on damaged mucosa; surfaces. These resembled the appearance normally associated with the gut of patients suffering from coeliac disease. Variations in the qualitative observations were seen in the schedules so that their interpretation in terms of perturbation of cellular kinetics is difficult. (author)

Surface Weather Observations

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Surface Weather Observation Collection consists primarily of hourly, synoptic, daily, and monthly forms submitted to the archive by the National Weather Service...

Uruguay - Surface Weather Observations

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Surface weather observation forms for 26 stations in Uruguay. Period of record 1896-2005, with two to eight observations per day. Files created through a...

Surface damage in TEM thick α-Fe samples by implantation with 150 keV Fe ions

International Nuclear Information System (INIS)

Aliaga, M.J.; Caturla, M.J.; Schäublin, R.

2015-01-01

We have performed molecular dynamics simulations of implantation of 150 keV Fe ions in pure bcc Fe. The thickness of the simulation box is of the same order of those used in in situ TEM analysis of irradiated materials. We assess the effect of the implantation angle and the presence of front and back surfaces. The number and type of defects, ion range, cluster distribution and primary damage morphology are studied. Results indicate that, for the very thin samples used in in situ TEM irradiation experiments the presence of surfaces affect dramatically the damage produced. At this particular energy, the ion has sufficient energy to damage both the top and the back surfaces and still leave the sample through the bottom. This provides new insights on the study of radiation damage using TEM in situ

Correlation of DT and DD fusion neutron damage in silicon surface barrier detector

International Nuclear Information System (INIS)

Iida, Toshiyuki; Sueyoshi, Yasuhiro; Sunarno; Takahashi, Akito

1994-01-01

In order to examine the correlation of DT and DD fusion neutron damage in Si, a silicon surface barrier detector (Si-SBD) was irradiation with neutrons from a deuteron accelerator. The leakage current increased proportionally with neutron fluence, which determined the neutron damage constant for the Si-SBD. The correlation factor of the DT and DD neutron damage in the Si-SBD was determined from the ratio of the DT and DD neutron damage constants and was found to be 2.3. We also calculated the rate of DT and DD neutron displacement damage for Si by using the TRIM-90 computer program and actual data on neutron reactions in the Si-SBD. The correlation factor of DT and DD neutron damage from the calculation agreed with that from the Si-SBD irradiation experiment. (author)

Quantification of acute vocal fold epithelial surface damage with increasing time and magnitude doses of vibration exposure.

Directory of Open Access Journals (Sweden)

Tsuyoshi Kojima

Full Text Available Because the vocal folds undergo repeated trauma during continuous cycles of vibration, the epithelium is routinely susceptible to damage during phonation. Excessive and prolonged vibration exposure is considered a significant predisposing factor in the development of vocal fold pathology. The purpose of the present study was to quantify the extent of epithelial surface damage following increased time and magnitude doses of vibration exposure using an in vivo rabbit phonation model. Forty-five New Zealand white breeder rabbits were randomized to nine groups and received varying phonation time-doses (30, 60, or 120 minutes and magnitude-doses (control, modal intensity phonation, or raised intensity phonation of vibration exposure. Scanning electron microscopy and transmission electron microscopy was used to quantify the degree of epithelial surface damage. Results revealed a significant reduction in microprojection density, microprojection height, and depth of the epithelial surface with increasing time and phonation magnitudes doses, signifying increased epithelial surface damage risk with excessive and prolonged vibration exposure. Destruction to the epithelial cell surface may provide significant insight into the disruption of cell function following prolonged vibration exposure. One important goal achieved in the present study was the quantification of epithelial surface damage using objective imaging criteria. These data provide an important foundation for future studies of long-term tissue recovery from excessive and prolonged vibration exposure.

Surface damage in the small intestine of the mouse after X - or neutron irradiation

International Nuclear Information System (INIS)

Hamlet, R.; Carr, K.E.; Nias, A.H.; Watt, C.

1981-01-01

Damage after X-irradiation includes lateral villous collapse, progressing after 3 - 5 days to villi which sometimes show signs of vertical collapse. After neutron irradiation vertical villous collapse is established earlier, with less swelling of villous tips. It seems, therefore, that at radiobiologically equivalent doses, neutron and X-irradiation produce different levels of surface damage, with neutron irradiation being the more destructive. Early villous tip damage may perhaps be due to disruption of susceptible cells already at the extrusion zone, or to stromal damage

Pulsed laser damage to optical fibers

International Nuclear Information System (INIS)

Allison, S.W.; Gillies, G.T.; Magnuson, D.W.; Pagano, T.S.

1985-01-01

This paper describes some observations of pulsed laser damage to optical fibers with emphasis on a damage mode characterized as a linear fracture along the outer core of a fiber. Damage threshold data are presented which illustrate the effects of the focusing lens, end-surface preparation, and type of fiber. An explanation based on fiber-beam misalignment is given and is illustrated by a simple experiment and ray trace

AFM assessment of the surface nano/microstructure on chemically damaged historical and model glasses

International Nuclear Information System (INIS)

Carmona, Noemi; Kowal, Andrzej; Rincon, Jesus-Maria; Villegas, Maria-Angeles

2010-01-01

Surface chemical damage on selected historical glasses from 13th to 19th centuries was evaluated by means of atomic force microscopy (AFM). Nano- and microstructure, roughness and topography of ancient glass samples have been compared with those of model glasses prepared by conventional melting at the laboratory with similar compositions to those most frequently found in historical glass pieces. The results obtained allow discussing the chemical degradation mechanisms in terms of the acid and/or basic chemical attack carried out by the combination of gaseous pollutants and environmental humidity. Even though deep corrosion features escape to the observation order of magnitude of the AF microscope used, the AFM technique proves to be quite useful for the study and evaluation of the most common surface pathologies of historical glasses with different compositions once submitted to natural weathering.

AFM assessment of the surface nano/microstructure on chemically damaged historical and model glasses

Energy Technology Data Exchange (ETDEWEB)

Carmona, Noemi [Centro Nacional de Investigaciones Metalurgicas, CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Kowal, Andrzej [Institute of Catalysis and Surface Chemistry, PAN, ul. Niezapominajek 8, 30239 Cracow (Poland); Rincon, Jesus-Maria [Instituto Eduardo Torroja de Ciencias de la Construccion, CSIC, C. Serrano Galvache s/n, 28033 Madrid (Spain); Villegas, Maria-Angeles, E-mail: mariangeles.villegas@cchs.csic.es [Centro Nacional de Investigaciones Metalurgicas, CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Instituto de Historia, Centro de Ciencias Humanas y Sociales, CSIC, C. Albasanz, 26-28, 28037 Madrid (Spain)

2010-01-15

Surface chemical damage on selected historical glasses from 13th to 19th centuries was evaluated by means of atomic force microscopy (AFM). Nano- and microstructure, roughness and topography of ancient glass samples have been compared with those of model glasses prepared by conventional melting at the laboratory with similar compositions to those most frequently found in historical glass pieces. The results obtained allow discussing the chemical degradation mechanisms in terms of the acid and/or basic chemical attack carried out by the combination of gaseous pollutants and environmental humidity. Even though deep corrosion features escape to the observation order of magnitude of the AF microscope used, the AFM technique proves to be quite useful for the study and evaluation of the most common surface pathologies of historical glasses with different compositions once submitted to natural weathering.

The apparent effect of sample surface damage on the dielectric parameters of GaAs

Energy Technology Data Exchange (ETDEWEB)

Engelbrecht, J.A.A. [Physics Department, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa)], E-mail: Japie.Engelbrecht@nmmu.ac.za; Hashe, N.G. [Physics Department, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Hillie, K.T. [CSIR-NML Laboratory, P.O. Box 395, Pretoria 0001 (South Africa); Claassens, C.H. [Physics Department, University of the Free State, Bloemfontein 9300 (South Africa)

2007-12-15

The dielectric and optical parameters determined by infrared reflectance spectroscopy and computer simulation of a set of GaAs substrates of various surface topologies are reported. The influence of surface damage on the parameters is noted.

The apparent effect of sample surface damage on the dielectric parameters of GaAs

International Nuclear Information System (INIS)

Engelbrecht, J.A.A.; Hashe, N.G.; Hillie, K.T.; Claassens, C.H.

2007-01-01

The dielectric and optical parameters determined by infrared reflectance spectroscopy and computer simulation of a set of GaAs substrates of various surface topologies are reported. The influence of surface damage on the parameters is noted

Condition Assessment for Wastewater Pipes: Method for Assessing Cracking and Surface Damage of Concrete Pipes

OpenAIRE

Hauge, Petter

2013-01-01

The objective of the Master Thesis has been to provide an improved method for condition assessment, which will give a better correlation between Condition class and actual Condition of concrete pipes with cracking and/or surface damages. Additionally improvement of the characterization of cracking (SR) and surface (KO) damages was a sub goal.Based on the findings described in my Thesis and my Specialization Project (Hauge 2012), I recommend that the Norwegian condition assessment method based...

Surface damage characterization of FBK devices for High Luminosity LHC (HL-LHC) operations

Science.gov (United States)

Moscatelli, F.; Passeri, D.; Morozzi, A.; Dalla Betta, G.-F.; Mattiazzo, S.; Bomben, M.; Bilei, G. M.

2017-12-01

The very high fluences (e.g. up to 2×1016 1 MeV neq/cm2) and total ionising doses (TID) of the order of 1 Grad, expected at the High Luminosity LHC (HL-LHC), impose new challenges for the design of effective, radiation resistant detectors. Ionising energy loss is the dominant effect for what concerns SiO2 and SiO2/Si interface radiation damage. In particular, surface damage can create a positive charge layer near the SiO2/Si interface and interface traps along the SiO2/Si interface, which strongly influence the breakdown voltage, the inter-electrode isolation and capacitance, and might also impact the charge collection properties of silicon sensors. To better understand in a comprehensive framework the complex and articulated phenomena related to surface damage at these very high doses, measurements on test structures have been carried out in this work (e.g. C-V and I-V). In particular, we have studied the properties of the SiO2 layer and of the SiO2/Si interface, using MOS capacitors, gated diodes (GD) and MOSFETs manufactured by FBK on high-resistivity n-type and p-type silicon, before and after irradiation with X-rays in the range from 50 krad(SiO2) to 20 Mrad(SiO2). Relevant parameters have been determined for all the tested devices, converging in the oxide charge density NOX, the surface generation velocity s0 and the integrated interface-trap density NIT dose-dependent values. These parameters have been extracted to both characterize the technology as a function of the dose and to be used in TCAD simulations for the surface damage effect modeling and the analysis and optimization of different classes of detectors for the next HEP experiments.

Preliminary observations of environmental damage due to the Gulf War

International Nuclear Information System (INIS)

El-Baz, F.

1992-01-01

Preparing for and conducting the Gulf War resulted in much damage to the environment of the region. The first and most visible effect is related to the damage caused by oil well fires in terms of air pollution as well as the potential damage to the petroleum reservoirs. The second detrimental effect has been caused by the oil spill in the Gulf water. Hundreds of miles of the western coastline of the Gulf are already covered with oil. Petroleum 'mats' have settled on coral reefs and have reduced Gulf water productivity. Foremost among the irreparable damages are changes to the terrain due to the digging of trenches, building walls of soil and otherwise disturbing the desert pavement in and around Kuwait. Disruption of the, usually, one-grain thick layer of pebbles on the desert floor exposes soil to wind action. Changing the contours of the normally flat land increases resistance to the wind and increases the potential of particle transport until the land is peneplained. This condition will increase the frequency and the ferocity of dust storms in the region. It will also result in the formation of new sand dunes; sand drifts already exist along roads in northern Kuwait. It is believed that the detrimental effects on the atmosphere will last for years, on the Gulf water for decades, and on the desert surface for centuries. (author). 12 refs, 1 fig

Preliminary observations of environmental damage due to the Gulf War

Energy Technology Data Exchange (ETDEWEB)

El-Baz, F [Boston Univ., Boston, MA (United States). Center for Remote Sensing

1992-02-01

Preparing for and conducting the Gulf War resulted in much damage to the environment of the region. The first and most visible effect is related to the damage caused by oil well fires in terms of air pollution as well as the potential damage to the petroleum reservoirs. The second detrimental effect has been caused by the oil spill in the Gulf water. Hundreds of miles of the western coastline of the Gulf are already covered with oil. Petroleum 'mats' have settled on coral reefs and have reduced Gulf water productivity. Foremost among the irreparable damages are changes to the terrain due to the digging of trenches, building walls of soil and otherwise disturbing the desert pavement in and around Kuwait. Disruption of the, usually, one-grain thick layer of pebbles on the desert floor exposes soil to wind action. Changing the contours of the normally flat land increases resistance to the wind and increases the potential of particle transport until the land is peneplained. This condition will increase the frequency and the ferocity of dust storms in the region. It will also result in the formation of new sand dunes; sand drifts already exist along roads in northern Kuwait. It is believed that the detrimental effects on the atmosphere will last for years, on the Gulf water for decades, and on the desert surface for centuries. (author). 12 refs, 1 fig.

Geometry and surface damage in micro electrical discharge machining of micro-holes

Science.gov (United States)

Ekmekci, Bülent; Sayar, Atakan; Tecelli Öpöz, Tahsin; Erden, Abdulkadir

2009-10-01

Geometry and subsurface damage of blind micro-holes produced by micro electrical discharge machining (micro-EDM) is investigated experimentally to explore the relational dependence with respect to pulse energy. For this purpose, micro-holes are machined with various pulse energies on plastic mold steel samples using a tungsten carbide tool electrode and a hydrocarbon-based dielectric liquid. Variations in the micro-hole geometry, micro-hole depth and over-cut in micro-hole diameter are measured. Then, unconventional etching agents are applied on the cross sections to examine micro structural alterations within the substrate. It is observed that the heat-damaged segment is composed of three distinctive layers, which have relatively high thicknesses and vary noticeably with respect to the drilling depth. Crack formation is identified on some sections of the micro-holes even by utilizing low pulse energies during machining. It is concluded that the cracking mechanism is different from cracks encountered on the surfaces when machining is performed by using the conventional EDM process. Moreover, an electrically conductive bridge between work material and debris particles is possible at the end tip during machining which leads to electric discharges between the piled segments of debris particles and the tool electrode during discharging.

Geometry and surface damage in micro electrical discharge machining of micro-holes

International Nuclear Information System (INIS)

Ekmekci, Bülent; Sayar, Atakan; Öpöz, Tahsin Tecelli; Erden, Abdulkadir

2009-01-01

Geometry and subsurface damage of blind micro-holes produced by micro electrical discharge machining (micro-EDM) is investigated experimentally to explore the relational dependence with respect to pulse energy. For this purpose, micro-holes are machined with various pulse energies on plastic mold steel samples using a tungsten carbide tool electrode and a hydrocarbon-based dielectric liquid. Variations in the micro-hole geometry, micro-hole depth and over-cut in micro-hole diameter are measured. Then, unconventional etching agents are applied on the cross sections to examine micro structural alterations within the substrate. It is observed that the heat-damaged segment is composed of three distinctive layers, which have relatively high thicknesses and vary noticeably with respect to the drilling depth. Crack formation is identified on some sections of the micro-holes even by utilizing low pulse energies during machining. It is concluded that the cracking mechanism is different from cracks encountered on the surfaces when machining is performed by using the conventional EDM process. Moreover, an electrically conductive bridge between work material and debris particles is possible at the end tip during machining which leads to electric discharges between the piled segments of debris particles and the tool electrode during discharging

Multi-scale fracture damage associated with underground chemical explosions

Science.gov (United States)

Swanson, E. M.; Sussman, A. J.; Wilson, J. E.; Townsend, M. J.; Prothro, L. B.; Gang, H. E.

2018-05-01

Understanding rock damage induced by explosions is critical for a number of applications including the monitoring and verification of underground nuclear explosions, mine safety issues, and modeling fluid flow through fractured rock. We use core observations, televiewer logs, and thin section observations to investigate fracture damage associated with two successive underground chemical explosions (SPE2 and SPE3) in granitic rock at both the mesoscale and microscale. We compare the frequency and orientations of core-scale fractures, and the frequency of microfractures, between a pre-experiment core and three post-experiment cores. Natural fault zones and explosion-induced fractures in the vicinity of the explosive source are readily apparent in recovered core and in thin sections. Damage from faults and explosions is not always apparent in fracture frequency plots from televiewer logs, although orientation data from these logs suggests explosion-induced fracturing may not align with the pre-existing fracture sets. Core-scale observations indicate the extent of explosion-induced damage is 10.0 m after SPE2 and 6.8 m after SPE3, despite both a similar size and location for both explosions. At the microscale, damage is observed to a range distance of 10.2 ± 0.9 m after SPE2, and 16.6 ± 0.9 and 11.2 ± 0.6 in two different cores collected after SPE3. Additional explosion-induced damage, interpreted to be the result of spalling, is readily apparent near the surface, but only in the microfracture data. This depth extent and intensity of damage in the near-surface region also increased after an additional explosion. This study highlights the importance of evaluating structural damage at multiple scales for a more complete characterization of the damage, and particularly shows the importance of microscale observations for identifying spallation-induced damage.

Activation of protein kinase A and clustering of cell surface receptors by N-methyl-N'-nitro-N-nitrosoguanidine are independent of genomic DNA damage

Energy Technology Data Exchange (ETDEWEB)

Wang Zheng; Wang Guliang; Yang Jun; Guo Lei; Yu Yingnian

2003-07-25

Alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) induces cellular stress leading to chromosomal aberrations, mutations and cell death. Previous reports from our laboratory have shown that low concentration of MNNG induces untargeted mutation (UTM), which occurs on intact DNA in mammalian cells through changes in gene expression profile. It also causes the activation of cAMP-protein kinase A (PKA) and up-regulation of POL-{beta}, which is demonstrated to play a role in DNA repair system. In order to find out the possible initial signal involved in UTM, we try to investigate whether the activation of PKA-CREB signal pathway is closely related to DNA damage. Our data shows that the treatment of low concentration MNNG (0.2 {mu}M) activates PKA-CREB pathway in a comparable level both in a nuclear and enucleated cell system. And similar to the cell response caused by UV, the clustering of cell surface receptors of epidermal growth factor (EGF) and tumor necrosis factor {alpha} (TNF{alpha}) was also observed in cells exposed to MNNG. It was further demonstrated that the clustering of the surface receptors is independent of the genomic DNA damage, as this phenomenon was also observed in enucleated cells. These observations indicate that the initiation of signal cascades induced by low concentration of MNNG might be associated with its interaction with cell surface receptors and/or direct activation of related signal proteins but not its DNA damaging property.

Application of Laser Pulse Heating to Simulate Thermomechanical Damage at Gun Bore Surfaces

National Research Council Canada - National Science Library

Cote, Paul

2003-01-01

Laser pulse heating experiments were performed to provide insights into the thermomechanical damage effects that occur at the surface of coated and uncoated gun steel under cyclic rapid heating and cooling...

Land Surface Weather Observations

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — METAR is the international standard code format for hourly surface weather observations. The acronym roughly translates from French as Aviation Routine Weather...

Measurement of radiation damage on an optical reflector

International Nuclear Information System (INIS)

Peng, K.C.; Sahu, S.K.; Huang, H.C.; Ueno, K.; Chang, Y.H.; Wang, C.H.; Hou, W.S.

1997-01-01

We measured the radiation damage on an optical white fluorocarbon reflector called Goretex, which is to be used for aerogel threshold counters and crystal calorimeters of the BELLE detector of the KEK B-factory. Reflectance of the Goretex surface was monitored to see any effect of the radiation damage. Maximum equivalent dose was 8.6 Mrad. No radiation damage is observed within measurement errors. (orig.)

Mexico - Surface Weather Observations

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Mexican Surface Daily Observations taken at 94 observatories located throughout Mexico, beginning in 1872 and going up through 1981. The data resided on paper...

In situ observations of microscale damage evolution in unidirectional natural fibre composites

DEFF Research Database (Denmark)

Rask, Morten; Madsen, Bo; Sørensen, Bent F.

2012-01-01

Synchrotron X-ray tomographic microscopy (XTM) has been used to observe in situ damage evolution in unidirectional flax fibre yarn/polypropylene composites loaded in uniaxial tension at stress levels between 20% and 95% of the ultimate failure stress. XTM allows for 3D visualization of the internal...... damage state at each stress level. The overall aim of the study is to gain a better understanding of the damage mechanisms in natural fibre composites. This is necessary if they are to be optimized to fulfil their promising potential. Three dominating damage mechanisms have been identified: (i) interface...... splitting cracks typically seen at the interfaces of bundles of unseparated fibres, (ii) matrix shear cracks, and (iii) fibre failures typically seen at fibre defects. Based on the findings in the present study, well separated fibres with a low number of defects are recommended for composite reinforcements....

Study of clean and ion bombardment damaged silver single crystal surfaces by work function measurements

International Nuclear Information System (INIS)

Chelvayohan, N.

1982-06-01

Work function values of the (110), (100) and (111) faces of silver single crystal were measured by the photoelectric emission method and found to be 4.14 +- 0.04 eV, 4.22 +-0.04 eV and 4.46 +- 0.02 eV respectively. Oxygen adsorption on the faces were studied by surface potential measurement. Strong oxygen adsorption was observed on (110) and (100) faces, whereas the (111) face was found to be inert for oxygen adsorption. Oxygen adsorption on the (111) face damaged by argon ion bombardment was also investigated. The above results were compared with those of early reported work function and oxygen adsorption values. (U.K.)

Damage and fatigue crack growth of Eurofer steel first wall mock-up under cyclic heat flux loads. Part 2: Finite element analysis of damage evolution

International Nuclear Information System (INIS)

You, Jeong-Ha

2014-01-01

Highlights: • The surface heat flux load of 3.5 MW/m 2 produced substantial stresses and inelastic strains in the heat-loaded surface region, especially at the notch root. • The notch root exhibited a typical notch effect such as stress concentration and localized inelastic yield leading to a preferred damage development. • The predicted damage evolution feature agrees well with the experimental observation. • The smooth surface also experiences considerable stresses and inelastic strains. However, the stress intensity and the amount of inelastic deformation are not high enough to cause any serious damage. • The level of maximum inelastic strain is higher at the notch root than at the smooth surface. On the other hand, the amplitude of inelastic strain variation is comparable at both positions. • The amount of inelastic deformation is significantly affected by the length of pulse duration time indicating the important role of creep. - Abstract: In the preceding companion article (part 1), the experimental results of the high-heat-flux (3.5 MW/m 2 ) fatigue tests of a Eurofer bare steel first wall mock-up was presented. The aim was to investigate the damage evolution and crack initiation feature. The mock-up used there was a simplified model having only basic and generic structural feature of an actively cooled steel FW component for DEMO reactor. In that study, it was found that microscopic damage was formed at the notch root already in the early stage of the fatigue loading. On the contrary, the heat-loaded smooth surface exhibited no damage up to 800 load cycles. In this paper, the high-heat-flux fatigue behavior is investigated with a finite element analysis to provide a theoretical interpretation. The thermal fatigue test was simulated using the coupled damage-viscoplastic constitutive model developed by Aktaa. The stresses, inelastic deformation and damage evolution at the notch groove and at the smooth surface are compared. The different damage

Surface Weather Observations Monthly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Surface Weather Observation 1001 Forms is a set of historical manuscript records for the period 1893-1948. The collection includes two very similar form types: Form...

Experimental study of surface quality and damage when drilling unidirectional CFRP composites

Directory of Open Access Journals (Sweden)

Eshetu D. Eneyew

2014-10-01

Full Text Available In this study, an experimental investigation on the drilling of unidirectional carbon fiber reinforced plastic (UD-CFRP composite was conducted using polycrystalline diamond (PCD tipped eight facet drill. The quality of the drilled hole surface was examined through surface roughness measurements and surface damage by scanning electron microscopy (SEM. It was found that fiber pullout occurred in two specific sectors relative to the angle between the cutting direction and the fiber orientation. The thrust force was highly influenced by the feed rate than the cutting speed and it shows a significant variation throughout the rotation of the drill.

Global Mercury Observation System (GMOS) surface observation data.

Data.gov (United States)

U.S. Environmental Protection Agency — GMOS global surface elemental mercury (Hg0) observations from 2013 & 2014. This dataset is associated with the following publication: Sprovieri, F., N. Pirrone,...

Surface structural damage associated with longwall mining near Tuscaloosa, Alabama: a case history

International Nuclear Information System (INIS)

Isphording, W.C.

1992-01-01

Initially the paper examines the frequency of coal mine subsidence and the influence on surface subsidence of subsurface mining methods, i.e. room and pillar and longwall mining. A case study of the subsidence damage caused to a log house near Tuscaloosa, Alabama (USA), when a longwall panel passed beneath it is presented. The damage resulted in the homeowners suing the mining company for negligence. The article discusses information provided to the plaintiffs attorneys by the author. Aspects covered are: the subsidence and damage to the property; prediction of subsidence; the monitoring of subsidence; and the prevention of subsidence. An out-of-court settlement was agreed by the two parties. 15 refs., 5 figs

Laser-Induced Damage with Femtosecond Pulses

Science.gov (United States)

Kafka, Kyle R. P.

The strong electric fields of focused femtosecond laser pulses lead to non-equilibrium dynamics in materials, which, beyond a threshold intensity, causes laser-induced damage (LID). Such a strongly non-linear and non-perturbative process renders important LID observables like fluence and intensity thresholds and damage morphology (crater) extremely difficult to predict quantitatively. However, femtosecond LID carries a high degree of precision, which has been exploited in various micro/nano-machining and surface engineering applications, such as human eye surgery and super-hydrophobic surfaces. This dissertation presents an array of experimental studies which have measured the damage behavior of various materials under femtosecond irradiation. Precision experiments were performed to produce extreme spatio-temporal confinement of the femtosecond laser-solid damage interaction on monocrystalline Cu, which made possible the first successful direct-benchmarking of LID simulation with realistic damage craters. A technique was developed to produce laser-induced periodic surface structures (LIPSS) in a single pulse (typically a multi-pulse phenomenon), and was used to perform a pump-probe study which revealed asynchronous LIPSS formation on copper. Combined with 1-D calculations, this new experimental result suggests more drastic electron heating than expected. Few-cycle pulses were used to study the LID performance and morphology of commercial ultra-broadband optics, which had not been systematically studied before. With extensive surface analysis, various morphologies were observed, including LIPSS, swelling (blisters), simple craters, and even ring-shaped structures, which varied depending on the coating design, number of pulses, and air/vacuum test environment. Mechanisms leading to these morphologies are discussed, many of which are ultrafast in nature. The applied damage behavior of multi-layer dielectric mirrors was measured and compared between long pulse (150 ps

Observation of damage process in RC beams under cucle bending by acoustic emission

International Nuclear Information System (INIS)

Shigeishi, Mitsuhiro; Ohtsu, Masayasu; Tsuji, Nobuyuki; Yasuoka, Daisuke

1997-01-01

Reinforced concrete (RC) structures are generally applied to construction of buildings and bridges, and are imposed on cyclic loading incessantly. It is considered that detected acoustic emission (AE) waveforms are associated with the damage degree and the fracture mechanisms of RC structures. Therefor, the cyclic bending tests are applied to damaged RC beam specimens. To evaluate the interior of the damaged RC beams, the AE source kinematics are determined by 'SiGMA' procedure for AE moment tensor analysis. By using 'SiGMA' procedure, AE source kinematics, such as source locations, crack types, crack orientations and crack motions, can be identified. The results show the applicability to observation of the fracture process under cyclic bending load and evaluation the degree of damage of RC beam.

Probability of growth of small damage sites on the exit surface of fused silica optics.

Science.gov (United States)

Negres, Raluca A; Abdulla, Ghaleb M; Cross, David A; Liao, Zhi M; Carr, Christopher W

2012-06-04

Growth of laser damage on fused silica optical components depends on several key parameters including laser fluence, wavelength, pulse duration, and site size. Here we investigate the growth behavior of small damage sites on the exit surface of SiO₂ optics under exposure to tightly controlled laser pulses. Results demonstrate that the onset of damage growth is not governed by a threshold, but is probabilistic in nature and depends both on the current size of a damage site and the laser fluence to which it is exposed. We also develop models for use in growth prediction. In addition, we show that laser exposure history also influences the behavior of individual sites.

Damage identification in beams by a response surface based technique

Directory of Open Access Journals (Sweden)

Teidj S.

2014-01-01

Full Text Available In this work, identification of damage in uniform homogeneous metallic beams was considered through the propagation of non dispersive elastic torsional waves. The proposed damage detection procedure consisted of the following sequence. Giving a localized torque excitation, having the form of a short half-sine pulse, the first step was calculating the transient solution of the resulting torsional wave. This torque could be generated in practice by means of asymmetric laser irradiation of the beam surface. Then, a localized defect assumed to be characterized by an abrupt reduction of beam section area with a given height and extent was placed at a known location of the beam. Next, the response in terms of transverse section rotation rate was obtained for a point situated afterwards the defect, where the sensor was positioned. This last could utilize in practice the concept of laser vibrometry. A parametric study has been conducted after that by using a full factorial design of experiments table and numerical simulations based on a finite difference characteristic scheme. This has enabled the derivation of a response surface model that was shown to represent adequately the response of the system in terms of the following factors: defect extent and severity. The final step was performing the inverse problem solution in order to identify the defect characteristics by using measurement.

[Scanning electron microscopy of heat-damaged bone tissue].

Science.gov (United States)

Harsanyl, L

1977-02-01

Parts of diaphyses of bones were exposed to high temperature of 200-1300 degrees C. Damage to the bone tissue caused by the heat was investigated. The scanning electron microscopic picture seems to be characteristic of the temperature applied. When the bones heated to the high temperature of 700 degrees C characteristic changes appear on the periostal surface, higher temperatura on the other hand causes damage to the compact bone tissue and can be observed on the fracture-surface. Author stresses the importance of this technique in the legal medicine and anthropology.

Observed damage during Argon gas cluster depth profiles of compound semiconductors

Energy Technology Data Exchange (ETDEWEB)

Barlow, Anders J., E-mail: anders.barlow@ncl.ac.uk; Portoles, Jose F.; Cumpson, Peter J. [National EPSRC XPS Users' Service (NEXUS), School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom)

2014-08-07

Argon Gas Cluster Ion Beam (GCIB) sources have become very popular in XPS and SIMS in recent years, due to the minimal chemical damage they introduce in the depth-profiling of polymer and other organic materials. These GCIB sources are therefore particularly useful for depth-profiling polymer and organic materials, but also (though more slowly) the surfaces of inorganic materials such as semiconductors, due to the lower roughness expected in cluster ion sputtering compared to that introduced by monatomic ions. We have examined experimentally a set of five compound semiconductors, cadmium telluride (CdTe), gallium arsenide (GaAs), gallium phosphide (GaP), indium arsenide (InAs), and zinc selenide (ZnSe) and a high-κ dielectric material, hafnium oxide (HfO), in their response to argon cluster profiling. An experimentally determined HfO etch rate of 0.025 nm/min (3.95 × 10{sup −2} amu/atom in ion) for 6 keV Ar gas clusters is used in the depth scale conversion for the profiles of the semiconductor materials. The assumption has been that, since the damage introduced into polymer materials is low, even though sputter yields are high, then there is little likelihood of damaging inorganic materials at all with cluster ions. This seems true in most cases; however, in this work, we report for the first time that this damage can in fact be very significant in the case of InAs, causing the formation of metallic indium that is readily visible even to the naked eye.

[Challenge and treatment strategy for ocular surface damage in patients with long term use of antiglaucoma drugs].

Science.gov (United States)

He, Xiang-Ge

2011-02-01

Long term use of topical anti-glaucoma drugs has been shown to induce chronic conjunctivitis, superficial punctate keratitis (SPK) and dry eye symptom. Under these conditions, a loss of goblet cells in conjunctiva, epithelial squamous metaplasia and apoptosis were morphologically revealed. Benzalkonium Chloride (BKC), a most frequently used preservative in eye drops, has been found to be an important factor causing ocular surface damage. Furthermore, a big challenge for ophthalmologists is that toxic damage of medication to ocular surface tissues is mild, poor specificity, and delayed manifestation in patients, especially when coexisting with other ocular surface diseases. Impairment of ocular surface tissues greatly impacts the life quality of patients and subsequently influences compliance with glaucoma therapy. This paper emphasizes to take measures to prevent ocular surface tissue damage resulted from chronic use of topical anti-glaucoma drugs and further discusses the treatment strategy. Effective and long-lasting action drugs should always be selected for glaucomatous patients in order to decrease the frequency of topical instillation or at a more expensive medication, a fixed combination formula can be considered for glaucoma therapy. An early surgery or laser treatment is also proposed for the patients who require an IOP reduction with an existing ocular surface impairment. Future investigation and development of new medications with long-term efficacy and appropriate BKC are suggested and preservative-free or drugs with new preservative materials recommended.

Damage behavior of REE-doped W-based material exposed to high-flux transient heat loads

International Nuclear Information System (INIS)

Shi, Jing; Luo, Lai–Ma; Lin, Jin–shan; Zan, Xiang; Zhu, Xiao–yong; Xu, Qiu; Wu, Yu–Cheng

2016-01-01

Pure W and W-Lu alloys were prepared by mechanical alloying (MA) and spark plasma sintering (SPS) technology. The performance and relevant damage mechanism of W-(0%, 2%, 5%, 10%) Lu alloys under transient heat loads were investigated using a laser beam heat load test to simulate the transient events in future nuclear fusion reactors. Scanning electron microscopy was used to observe the morphologies of the damaged surfaces and energy dispersive X-ray spectroscopy was used to conduct composition analysis. Damages to the surface such as cracks, pits, melting layers, Lu-rich droplets, and thermal ablation were observed. A mass of dense fuzz-like nanoparticles formed on the outer region of the laser-exposed area. Recrystallization, grain growth, increased surface roughness, and material erosion were also observed. W-Lu samples with low Lu content demonstrated better thermal performance than pure W, and the degree of damage significantly deteriorated under repetitive transient heat loads.

In situ observation of mechanical damage within a SiC-SiC ceramic matrix composite

Energy Technology Data Exchange (ETDEWEB)

Saucedo-Mora, L. [Institute Eduardo Torroja for Construction Sciences-CSIC, Madrid (Spain); Department of Materials, University of Oxford (United Kingdom); Lowe, T. [Manchester X-ray Imaging Facility, The University of Manchester (United Kingdom); Zhao, S. [Department of Materials, University of Oxford (United Kingdom); Lee, P.D. [Research Complex at Harwell, Rutherford Appleton Laboratory (United Kingdom); Mummery, P.M. [School of Mechanical, Aerospace and Civil Engineering, The University of Manchester (United Kingdom); Marrow, T.J., E-mail: james.marrow@materials.ox.ac.uk [Department of Materials, University of Oxford (United Kingdom)

2016-12-01

SiC-SiC ceramic matrix composites are candidate materials for fuel cladding in Generation IV nuclear fission reactors and as accident tolerant fuel clad in current generation plant. Experimental methods are needed that can detect and quantify the development of mechanical damage, to support modelling and qualification tests for these critical components. In situ observations of damage development have been obtained of tensile and C-ring mechanical test specimens of a braided nuclear grade SiC-SiC ceramic composite tube, using a combination of ex situ and in situ computed X-ray tomography observation and digital volume correlation analysis. The gradual development of damage by matrix cracking and also the influence of non-uniform loading are examined. - Highlights: • X-ray tomography with digital volume correlation measures 3D deformation in situ. • Cracking and damage in the microstructure can be detected using the strain field. • Fracture can initiate from the monolithic coating of a SiC-SiC ceramic composite.

In situ observation of mechanical damage within a SiC-SiC ceramic matrix composite

International Nuclear Information System (INIS)

Saucedo-Mora, L.; Lowe, T.; Zhao, S.; Lee, P.D.; Mummery, P.M.; Marrow, T.J.

2016-01-01

SiC-SiC ceramic matrix composites are candidate materials for fuel cladding in Generation IV nuclear fission reactors and as accident tolerant fuel clad in current generation plant. Experimental methods are needed that can detect and quantify the development of mechanical damage, to support modelling and qualification tests for these critical components. In situ observations of damage development have been obtained of tensile and C-ring mechanical test specimens of a braided nuclear grade SiC-SiC ceramic composite tube, using a combination of ex situ and in situ computed X-ray tomography observation and digital volume correlation analysis. The gradual development of damage by matrix cracking and also the influence of non-uniform loading are examined. - Highlights: • X-ray tomography with digital volume correlation measures 3D deformation in situ. • Cracking and damage in the microstructure can be detected using the strain field. • Fracture can initiate from the monolithic coating of a SiC-SiC ceramic composite.

Observation of gliding arc surface treatment

DEFF Research Database (Denmark)

Kusano, Yukihiro; Zhu, Jiajian; Ehn, A.

2015-01-01

. Water contact angle measurements indicate that the treatment uniformity improves significantly when the AC gliding arc is tilted to the polymer surface. Thickness reduction of the gas boundary layer, explaining the improvement of surface treatment, by the ultrasonic irradiation was directly observed...

A new surface fractal dimension for displacement mode shape-based damage identification of plate-type structures

Science.gov (United States)

Shi, Binkai; Qiao, Pizhong

2018-03-01

Vibration-based nondestructive testing is an area of growing interest and worthy of exploring new and innovative approaches. The displacement mode shape is often chosen to identify damage due to its local detailed characteristic and less sensitivity to surrounding noise. Requirement for baseline mode shape in most vibration-based damage identification limits application of such a strategy. In this study, a new surface fractal dimension called edge perimeter dimension (EPD) is formulated, from which an EPD-based window dimension locus (EPD-WDL) algorithm for irregularity or damage identification of plate-type structures is established. An analytical notch-type damage model of simply-supported plates is proposed to evaluate notch effect on plate vibration performance; while a sub-domain of notch cases with less effect is selected to investigate robustness of the proposed damage identification algorithm. Then, fundamental aspects of EPD-WDL algorithm in term of notch localization, notch quantification, and noise immunity are assessed. A mathematical solution called isomorphism is implemented to remove false peaks caused by inflexions of mode shapes when applying the EPD-WDL algorithm to higher mode shapes. The effectiveness and practicability of the EPD-WDL algorithm are demonstrated by an experimental procedure on damage identification of an artificially-induced notched aluminum cantilever plate using a measurement system of piezoelectric lead-zirconate (PZT) actuator and scanning laser Doppler vibrometer (SLDV). As demonstrated in both the analytical and experimental evaluations, the new surface fractal dimension technique developed is capable of effectively identifying damage in plate-type structures.

The study of sub-surface damage distributions during grinding process on different abrasion materials

Science.gov (United States)

Kuo, Ching-Hsiang; Huang, Chien-Yao; Yu, Zong-Ru; Shu, Shyu-Cheng; Chang, Keng-Shou; Hsu, Wei-Yao

2017-10-01

The grinding process is the primary technology for curvature generation (CG) on glass optics. The higher material removal rate (MRR) leads to deeper sub-surface damage (SSD) on lens surface. The SSD must be removed by following lapping and polishing processes to ensure the lens quality. However, these are not an easy and an efficient process to remove the SSD from ground surface directly for aspheric surfaces with tens or hundreds microns departure from bestfit- sphere (BFS). An efficient fabrication procedure for large aspheric departure on glass materials must be considered. We propose 3-step fabrication procedures for aspheric surface with larger departure. 1st step is to generate a specific aspheric surface with depth less than 10 μm of SSD residual. 2nd step is to remove SSD and keep the aspheric form by using Zeeko polisher with higher MRR pad. Final step is to figure and finish the aspheric surface by using QED MRF machine. In this study, we focus on the 1st step to investigate the residual depth of SSD after grinding process on different abrasion materials. The materials of tested part are fused silica, S-NPH2, and S-PHM52. The cross grinding would be configured and depth of SSD/surface roughness would be evaluated in this study. The characteristic of SSD could be observed after etching by confocal microscope. The experimental results show the depth of SSD below 31.1 μm with #400 grinding wheel. And the near 10 μm depth of SSD would be achieved with #1,000 grinding wheel. It means the aspherization polishing on large parts with large departure from best fit sphere would be replaced. The fabrication of large aspheric part would be efficient.

Surface Contaminant Control Technologies to Improve Laser Damage Resistance of Optics

Directory of Open Access Journals (Sweden)

Xiaofeng Cheng

2014-01-01

Full Text Available The large high-power solid lasers, such as the National Ignition Facility (NIF of America and the Shenguang-III (SG-III laser facility of China, can output over 2.1 MJ laser pulse for the inertial confinement fusion (ICF experiments. Because of the enhancement of operating flux and the expansion of laser driver scale, the problem of contamination seriously influences their construction period and operation life. During irradiation by intense laser beams, the contaminants on the metallic surface of beam tubes can be transmitted to the optical surfaces and lead to damage of optical components. For the high-power solid-state laser facilities, contamination control focuses on the slab amplifiers, spatial filters, and final-optical assemblies. In this paper, an effective solution to control contaminations including the whole process of the laser driver is put forward to provide the safe operation of laser facilities, and the detailed technical methods of contamination control such as washing, cleanliness metrology, and cleanliness protecting are also introduced to reduce the probability of laser-induced damage of optics. The experimental results show that the cleanliness level of SG-III laser facility is much better to ensure that the laser facility can safely operate at high energy flux.

Comparison of laser-based mitigation of fused silica surface damage using mid- versus far-infrared lasers

Energy Technology Data Exchange (ETDEWEB)

Yang, S T; Matthews, M J; Elhadj, S; Cooke, D; Guss, G M; Draggoo, V G; Wegner, P J

2009-12-16

Laser induced growth of optical damage can limit component lifetime and therefore operating costs of large-aperture fusion-class laser systems. While far-infrared (IR) lasers have been used previously to treat laser damage on fused silica optics and render it benign, little is known about the effectiveness of less-absorbing mid-IR lasers for this purpose. In this study, they quantitatively compare the effectiveness and efficiency of mid-IR (4.6 {micro}m) versus far-IR (10.6 {micro}m) lasers in mitigating damage growth on fused silica surfaces. The non-linear volumetric heating due to mid-IR laser absorption is analyzed by solving the heat equation numerically, taking into account the temperature-dependent absorption coefficient {alpha}(T) at {lambda} = 4.6 {micro}m, while far-IR laser heating is well-described by a linear analytic approximation to the laser-driven temperature rise. In both cases, the predicted results agree well with surface temperature measurements based on infrared radiometry, as well as sub-surface fictive temperature measurements based on confocal Raman microscopy. Damage mitigation efficiency is assessed using a figure of merit (FOM) relating the crack healing depth to laser power required, under minimally-ablative conditions. Based on their FOM, they show that for cracks up to at least 500 {micro}m in depth, mitigation with a 4.6 {micro}m mid-IR laser is more efficient than mitigation with a 10.6 {micro}m far-IR laser. This conclusion is corroborated by direct application of each laser system to the mitigation of pulsed laser-induced damage possessing fractures up to 225 {micro}m in depth.

Fatigue damage behavior of a surface-mount electronic package under different cyclic applied loads

Science.gov (United States)

Ren, Huai-Hui; Wang, Xi-Shu

2014-04-01

This paper studies and compares the effects of pull-pull and 3-point bending cyclic loadings on the mechanical fatigue damage behaviors of a solder joint in a surface-mount electronic package. The comparisons are based on experimental investigations using scanning electron microscopy (SEM) in-situ technology and nonlinear finite element modeling, respectively. The compared results indicate that there are different threshold levels of plastic strain for the initial damage of solder joints under two cyclic applied loads; meanwhile, fatigue crack initiation occurs at different locations, and the accumulation of equivalent plastic strain determines the trend and direction of fatigue crack propagation. In addition, simulation results of the fatigue damage process of solder joints considering a constitutive model of damage initiation criteria for ductile materials and damage evolution based on accumulating inelastic hysteresis energy are identical to the experimental results. The actual fatigue life of the solder joint is almost the same and demonstrates that the FE modeling used in this study can provide an accurate prediction of solder joint fatigue failure.

OBSERVED ASTEROID SURFACE AREA IN THE THERMAL INFRARED

Energy Technology Data Exchange (ETDEWEB)

Nugent, C. R. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Mainzer, A.; Masiero, J.; Bauer, J.; Kramer, E.; Sonnett, S. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Wright, E. L. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Grav, T. [Planetary Science Institute, Tucson, AZ (United States)

2017-02-01

The rapid accumulation of thermal infrared observations and shape models of asteroids has led to increased interest in thermophysical modeling. Most of these infrared observations are unresolved. We consider what fraction of an asteroid’s surface area contributes the bulk of the emitted thermal flux for two model asteroids of different shapes over a range of thermal parameters. The resulting observed surface in the infrared is generally more fragmented than the area observed in visible wavelengths, indicating high sensitivity to shape. For objects with low values of the thermal parameter, small fractions of the surface contribute the majority of thermally emitted flux. Calculating observed areas could enable the production of spatially resolved thermal inertia maps from non-resolved observations of asteroids.

Earthquake damage to underground facilities

International Nuclear Information System (INIS)

Pratt, H.R.; Hustrulid, W.A.; Stephenson, D.E.

1978-11-01

The potential seismic risk for an underground nuclear waste repository will be one of the considerations in evaluating its ultimate location. However, the risk to subsurface facilities cannot be judged by applying intensity ratings derived from the surface effects of an earthquake. A literature review and analysis were performed to document the damage and non-damage due to earthquakes to underground facilities. Damage from earthquakes to tunnels, s, and wells and damage (rock bursts) from mining operations were investigated. Damage from documented nuclear events was also included in the study where applicable. There are very few data on damage in the subsurface due to earthquakes. This fact itself attests to the lessened effect of earthquakes in the subsurface because mines exist in areas where strong earthquakes have done extensive surface damage. More damage is reported in shallow tunnels near the surface than in deep mines. In mines and tunnels, large displacements occur primarily along pre-existing faults and fractures or at the surface entrance to these facilities.Data indicate vertical structures such as wells and shafts are less susceptible to damage than surface facilities. More analysis is required before seismic criteria can be formulated for the siting of a nuclear waste repository

ALMA observation of Ceres' Surface Temperature.

Science.gov (United States)

Titus, T. N.; Li, J. Y.; Sykes, M. V.; Ip, W. H.; Lai, I.; Moullet, A.

2016-12-01

Ceres, the largest object in the main asteroid belt, has been mapped by the Dawn spacecraft. The mapping includes measuring surface temperatures using the Visible and Infrared (VIR) spectrometer at high spatial resolution. However, the VIR instrument has a long wavelength cutoff at 5 μm, which prevents the accurate measurement of surface temperatures below 180 K. This restricts temperature determinations to low and mid-latitudes at mid-day. Observations from the Atacama Large Millimeter/submillimeter Array (ALMA) [1], while having lower spatial resolution, are sensitive to the full range of surface temperatures that are expected at Ceres. Forty reconstructed images at 75 km/beam resolution were acquired of Ceres that were consistent with a low thermal inertia surface. The diurnal temperature profiles were compared to the KRC thermal model [2, 3], which has been extensively used for Mars [e.g. 4, 5]. Variations in temperature as a function of local time are observed and are compared to predictions from the KRC model. The model temperatures are converted to radiance (Jy/Steradian) and are corrected for near-surface thermal gradients and limb effects for comparison to observations. Initial analysis is consistent with the presence of near-surface water ice in the north polar region. The edge of the ice table is between 50° and 70° North Latitude, consistent with the enhanced detection of hydrogen by the Dawn GRaND instrument [6]. Further analysis will be presented. This work is supported by the NASA Solar System Observations Program. References: [1] Wootten A. et al. (2015) IAU General Assembly, Meeting #29, #2237199 [2] Kieffer, H. H., et al. (1977) JGR, 82, 4249-4291. [3] Kieffer, Hugh H., (2013) Journal of Geophysical Research: Planets, 118(3), 451-470. [4] Titus, T. N., H. H. Kieffer, and P. N. Christensen (2003) Science, 299, 1048-1051. [5] Fergason, R. L. et al. (2012) Space Sci. Rev, 170, 739-773[6] Prettyman, T. et al. (2016) LPSC 47, #2228.

Growth of Laser Initiated Damage in Fused Silica at 527 nm

International Nuclear Information System (INIS)

Norton, M A; Donohue, E E; Hollingsworth, W G; McElroy, J N; Hackel, R P

2003-01-01

The effective lifetime of optics is limited by both laser-induced damage and the subsequent growth of laser initiated damage sites. We have measured the growth rate of laser-induced damage in fused silica in both air and vacuum at 527 nm. For damage on the exit surface, the data shows exponential growth in the lateral size of the damage site with shot number. The exponential growth coefficient depends linearly on the laser fluence. The behavior at the fluence threshold for growth is contrasted to that observed at 351 nm. The growth rate was not significantly affected by either the wavelength of the initiating fluence or the presence of 10 torr of air as compared to vacuum. When the damage is located on the input surface, it has both a higher threshold for growth and does not grow exponentially

High-Damage-Threshold Pinhole for Glass Fusion Laser Applications

International Nuclear Information System (INIS)

Kumit, N.A.; Letzring, S.A.; Johnson, R.P.

1998-01-01

We are investigating methods to fabricate high-damage-threshold spatial-filter pinholes that might not be susceptible to plasma closure for relatively high energies and long pulses. These are based on the observation that grazing-incidence reflection from glass can withstand in excess of 5 kJ/cm 2 (normal to the beam) without plasma formation. The high damage threshold results from both the cos q spreading of the energy across the surface and the reflection of a large fraction of the energy from the surface, thereby greatly reducing the field strength within the medium

Ion irradiation damage in ilmenite at 100 K

International Nuclear Information System (INIS)

Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A.

1997-01-01

A natural single crystal of ilmenite (FeTiO 3 ) was irradiated at 100 K with 200 keV Ar 2+ . Rutherford backscattering spectroscopy and ion channeling with MeV He + ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 x 10 15 Ar 2+ cm -2 , considerable near-surface He + ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 nm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO 3 ) and spinel (MgAl 2 O 4 ) to explore factors that may influence radiation damage response in oxides

Ion irradiation damage in ilmenite under cryogenic conditions

International Nuclear Information System (INIS)

Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A.

1996-01-01

A natural single crystal of ilmenite was irradiated at 100 K with 200 keV Ar 2+ . Rutherford backscattering spectroscopy and ion channeling with 2 MeV He + ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 x 10 15 Ar 2+ cm -2 , considerable near-surface He + ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 mm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO 3 ) and spinel (MgAl 2 O 4 ) to explore factors that may influence radiation damage response in oxides

Ion irradiation damage in ilmenite at 100 K

Science.gov (United States)

Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A.; Nord, G.L.

1997-01-01

A natural single crystal of ilmenite (FeTiO3) was irradiated at 100 K with 200 keV Ar2+. Rutherford backscattering spectroscopy and ion channeling with 2 MeV He+ ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 ?? 1015 Ar2+/cm2, considerable near-surface He+ ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 nm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO3) and spinel (MgAl2O4) to explore factors that may influence radiation damage response in oxides.

Increased effects of machining damage in beryllium observed at high strain rates

International Nuclear Information System (INIS)

Beitscher, S.; Brewer, A.W.; Corle, R.R.

1980-01-01

Tensile tests at both low and high strain rates, and also impact shear tests, were performed on a weldable grade powder-source beryllium. Impact energies increased by a factor of 2 to 3 from the as-machined level after etching or annealing. Similar increases in the ductility from machining damage removal were observed from the tensile data at the higher strain rate (10 s -1 ) while an insignificant increase in elongation was measured at the lower strain rate (10 -4 s -1 ). High strain-rate tests appear to be more sensitive and reliable for evaluating machining practice and damage removal methods for beryllium components subjected to sudden loads. 2 tables

The size prediction of potential inclusions embedded in the sub-surface of fused silica by damage morphology

Directory of Open Access Journals (Sweden)

Gao Xiang

2017-04-01

Full Text Available A model for predicting the size ranges of different potential inclusions initiating damage on the surface of fused silica has been presented. This accounts for the heating of nanometric inclusions whose absorptivity is described based on Mie Theory. The depth profile of impurities has been measured by ICP-OES. By the measured temporal pulse profile on the surface of fused silica, the temperature and thermal stress has been calculated. Furthermore, considering the limit conditions of temperature and thermal stress strength for different damage morphologies, the size range of potential inclusions for fused silica is discussed.

GODAE, SFCOBS - Surface Temperature Observations, 1998-present

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — GODAE, SFCOBS - Surface Temperature Observations: Ship, fixed/drifting buoy, and CMAN in-situ surface temperature. Global Telecommunication System (GTS) Data. The...

Cavitation damage prediction for the JSNS mercury target vessel

Energy Technology Data Exchange (ETDEWEB)

Naoe, Takashi, E-mail: naoe.takashi@jaea.go.jp; Kogawa, Hiroyuki; Wakui, Takashi; Haga, Katsuhiro; Teshigawara, Makoto; Kinoshita, Hidetaka; Takada, Hiroshi; Futakawa, Masatoshi

2016-01-15

The liquid mercury target system for the Japan Spallation Neutron Source (JSNS) at the Materials and Life science experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC) is designed to produce pulsed neutrons. The mercury target vessel in this system, which is made of type 316L stainless steel, is damaged by pressure wave-induced cavitation due to proton beam bombardment. Currently, cavitation damage is considered to be the dominant factor influencing the service life of the target vessel rather than radiation damage. In this study, cavitation damage to the interior surface of the target vessel was predicted on the basis of accumulated damage data from off-beam and on-beam experiments. The predicted damage was compared with the damage observed in a used target vessel. Furthermore, the effect of injecting gas microbubbles on cavitation damage was predicted through the measurement of the acoustic vibration of the target vessel. It was shown that the predicted depth of cavitation damage is reasonably coincident with the observed results. Moreover, it was confirmed that the injection of gas microbubbles had an effect on cavitation damage.

Reactive ion beam etching for microcavity surface emitting laser fabrication: technology and damage characterization

International Nuclear Information System (INIS)

Matsutani, A.; Tadokoro, T.; Koyama, F.; Iga, K.

1993-01-01

Reactive ion beam etching (RIBE) is an effective dry etching technique for the fabrication of micro-sized surface emitting (SE) lasers and optoelectronic devices. In this chapter, some etching characteristics for GaAs, InP and GaInAsP with a Cl 2 gas using an RIBE system are discussed. Micro-sized circular mesas including GaInAsP/InP multilayers with vertical sidewalls were fabricated. RIBE-induced damage in InP substrates was estimated by C-V and PL measurement. In addition, the removal of the induced damage by the second RIBE with different conditions for the InP wafer was proposed. The sidewall damage is characterized by photoluminescence emitted from the etched sidewall of a GaInAsP/InP DH wafer. (orig.)

A Method to Simulate the Observed Surface Properties of Proton Irradiated Silicon Strip Sensors

CERN Document Server

INSPIRE-00335524; Bhardwaj, A.; Dalal, R.; Eber, R.; Eichhorn, T.; Lalwani, K.; Messineo, A.; Printz, M.; Ranjan, K.

2015-04-23

During the scheduled high luminosity upgrade of LHC, the world's largest particle physics accelerator at CERN, the position sensitive silicon detectors installed in the vertex and tracking part of the CMS experiment will face more intense radiation environment than the present system was designed for. To upgrade the tracker to required performance level, extensive measurements and simulations studies have already been carried out. A defect model of Synopsys Sentaurus TCAD simulation package for the bulk properties of proton irradiated devices has been producing simulations closely matching with measurements of silicon strip detectors. However, the model does not provide expected behavior due to the fluence increased surface damage. The solution requires an approach that does not affect the accurate bulk properties produced by the proton model, but only adds to it the required radiation induced properties close to the surface. These include the observed position dependency of the strip detector's charge collec...

The Influence of Ballistic Damage on the Aeroelastic Characteristics of Lifting Surfaces.

Science.gov (United States)

1979-07-01

tunnel wall was sealed with a flexible rubber gasket. The pressure measurements were made using Scanivalve pressure multiplexers and DRUCK pressure...discharge, having a 1.52 by 2.13 m (5 x 7 ft) test section. The drive system comprises four fans of 200 hp each, DRUCK model PDCR differential pressure...3, 4, 5, 6, 8, 9 Surface # IC LS 1 3 2 2 4 2 3 2 2 4 3 2 5 4 2 6 2 2 7 3 3 8 4 3 9 2 3 Damaged - Cases: ID, 2D, 3D , 4D, 5D, 6D, 8D, 9D 1 .Surface # IC

Roller Testing to Mimic Damage of the ISS SARJ Ring and Durability Test to Simulate Fifteen Years of SARJ Operation Using the Damaged Surface

Science.gov (United States)

Krantz, Timothy L.; Elchert, Justin P.; DellaCorte, Christopher; Dube, Michael J.

2016-01-01

The International Space Station's starboard Solar Alpha Rotary Joint (SARJ) experienced a breakdown of the joint's race ring surface. The starboard SARJ mechanism was cleaned and lubricated with grease. To provide some guidance on the expected behavior of the damaged SARJ ring with continued operations, experiments were conducted using rollers and a vacuum roller test rig. The approach of the experimental work involved three main steps: (1) initiate damage using conditions representative of the SARJ with inadequate lubrication; (2) propagate the damage by operating the test rollers without lubrication; and (3) assess the durability of the roller by testing to simulate the equivalent of 15 years of SARJ operation on the damaged surface assuming adequate grease lubrication. During the rig testing, additional and/or replacement grease was introduced at regular intervals to maintain good lubrication in the rig. The damage to the nitride layer continued even after application of grease. The grease lubrication proved to be effective for limiting the value of the axial force that can be developed. Limiting the axial force on the SARJ mechanism is important since the larger the axial force the more concentrated the load pressure becomes on the blend-radius location on the SARJ roller. After the testing simulating 15 years of SARJ operations, the wear depths were the order of 0.2 mm for the nitrided 15-5 roller and the order of 0.06 mm for the mating 440C roller. Metallographic inspections were done to search for indications of impending fatigue or other fracture indications that might eventually propagate and cause structural failure. There were no indications or features found that could eventually compromise structural integrity.

Frost damage of concrete subject to confinement

DEFF Research Database (Denmark)

Hasholt, Marianne Tange

2016-01-01

When internal frost damage is observed in real concrete structures, the usual pattern is cracks with a preferred orientation parallel to the exposed surface. When exposing concrete with poor frost resistance to a standardised freeze/thaw test in the laboratory, the orientations of the resulting...

Bulk and surface laser damage of silica by picosecond and nanosecond pulses at 1064 nm

International Nuclear Information System (INIS)

Smith, Arlee V.; Do, Binh T.

2008-01-01

We measured bulk and surface dielectric breakdown thresholds of pure silica for 14 ps and 8 ns pulses of 1064 nm light. The thresholds are sharp and reproducible. For the 8 ns pulses the bulk threshold irradiance is 4.75 ± 0.25 kW/μm 2 . The threshold is approximately three times higher for 14 ps pulses. For 8 ns pulses the input surface damage threshold can be made equal to the bulk threshold by applying an alumina or silica surface polish

Observation of optimal gecko's adhesion on nanorough surfaces.

Science.gov (United States)

Pugno, Nicola M; Lepore, Emiliano

2008-12-01

In this letter we report experimental observations on the times of adhesion of living Tokay geckos (Gekko geckos) on polymethylmethacrylate (PMMA) inverted surfaces. Two different geckos (male and female) and three surfaces with different root mean square (RMS) roughness (RMS=42, 618 and 931 nm) have been considered, for a total of 72 observations. The measured data are proved to be statistically significant, following the Weibull Statistics with coefficients of correlation between 0.781 and 0.955. The unexpected result is the observation of a maximal gecko adhesion on the surface with intermediate roughness of RMS=618 nm, that we note has waviness comparable to the seta size.

Surface damage of W exposed to combined stationary D plasma and ELMs-like pulsed plasma

Energy Technology Data Exchange (ETDEWEB)

Jia, Y.Z., E-mail: jaja880816@aliyun.com [Science and Technology on Reactor Fuel and Materials Laboratory, Nuclear Power Institute of China, Chengdu, Sichuan 610213 (China); Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu, W., E-mail: liuw@mail.tsinghua.edu.cn [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Xu, B.; Qu, S.L. [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Morgan, T.W. [FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, 5612AJ Eindhoven (Netherlands)

2017-04-15

The surface damage of W under D plasma and ELMs-like transient heat loads was studied by combined stationary and pulsed D plasma. Low-flux transient heat loads will promote blister formation due to the gas expansion inside the blisters. On the contrary, high-flux transient heat loads will mitigate blistering due to the high surface temperature. Therefore, blistering on W surface first increased and then decreased with the increasing transient heat loads. The promotion effect of pulsed plasma on blistering is more obvious on [001] and [110] surfaces than on [111] surface, and the orientation dependence of blisters was mitigated by the transient heat loads. Surface modification induced by transient heat loads only formed on [001] and [110] surfaces, but did not form on [111] surface. The orientation dependence of surface modification was mainly due to the slipping system of dislocations.

Mitigation technologies for damage induced by pressure waves in high-power mercury spallation neutron sources (1). Material surface improvement

International Nuclear Information System (INIS)

Naoe, Takashi; Futakawa, Masatoshi; Wakui, Takashi; Kogawa, Hiroyuki; Shoubu, Takahisa; Takeuchi, Hirotsugu; Kawai, Masayoshi

2008-01-01

Liquid-mercury target systems for MW-class spallation neutron sources are being developed in the world. Proton beams will be used to induce the spallation reaction. At the moment the proton beam hits the target, pressure waves are generated in the mercury because of the abrupt heat deposition. The pressure waves interact with the target vessel leading to negative pressure that may cause cavitation along the vessel wall. Localized impacts by microjets and/or shock waves that are caused by cavitation bubble collapse impose pitting damage on the vessel wall. Bubble collapse behavior was observed by using a high-speed video camera, as well as simulated numerically. Localized impact due to cavitation bubble collapse was quantitatively estimated through comparison between numerical simulation and experiment. A novel surface treatment technique that consists of carburizing and nitriding processes was developed and the treatment condition was optimized to mitigate the pitting damage due to localized impacts. (author)

Surface analysis of transition metal oxalates: Damage aspects

Energy Technology Data Exchange (ETDEWEB)

Chenakin, S.P., E-mail: chenakin@imp.kiev.ua [Université Libre de Bruxelles (ULB), Chimie-Physique des Matériaux, B-1050 Bruxelles (Belgium); Institute of Metal Physics, Nat. Acad. Sci. of Ukraine, Akad. Vernadsky Blvd. 36, 03680 Kiev (Ukraine); Szukiewicz, R. [Université Libre de Bruxelles (ULB), Chimie-Physique des Matériaux, B-1050 Bruxelles (Belgium); Barbosa, R.; Kruse, N. [Université Libre de Bruxelles (ULB), Chimie-Physique des Matériaux, B-1050 Bruxelles (Belgium); Voiland School of Chemical Engineering and Bioengineering, Washington State University, 155 Wegner Hall, Pullman, WA 99164-6515 (United States)

2016-05-15

Highlights: • Gas evolution from the Mn, Co, Ni and Cu oxalate hydrates in vacuum, during exposure to X-rays and after termination of X-ray irradiation is studied. • A comparative study of the damage caused by X-rays in NiC{sub 2}O{sub 4} and CuC{sub 2}O{sub 4} is carried out. • Effect of Ar{sup +} bombardment on the structure and composition of CoC{sub 2}O{sub 4} is studied. - Abstract: The behavior of transition metal oxalates in vacuum, under X-ray irradiation and low-energy Ar{sup +} ion bombardment was studied. A comparative mass-spectrometric analysis was carried out of gas evolution from the surface of Mn, Co, Ni and Cu oxalate hydrates in vacuum, during exposure to X-rays and after termination of X-ray irradiation. The rates of H{sub 2}O and CO{sub 2} liberation from the oxalates were found to be in an inverse correlation with the temperatures of dehydration and decomposition, respectively. X-ray photoelectron spectroscopy (XPS) was employed to study the X-ray induced damage in NiC{sub 2}O{sub 4} and CuC{sub 2}O{sub 4} by measuring the various XP spectral characteristics and surface composition of the oxalates as a function of time of exposure to X-rays. It was shown that Cu oxalate underwent a significantly faster degradation than Ni oxalate and demonstrated a high degree of X-ray induced reduction from the Cu{sup 2+} to the Cu{sup 1+} chemical state. 500 eV Ar{sup +} sputter cleaning of CoC{sub 2}O{sub 4} for 10 min was found to cause a strong transformation of the oxalate structure which manifested itself in an appreciable alteration of the XP core-level and valence band spectra. The analysis of changes in stoichiometry and comparison of XP spectra of bombarded oxalate with respective spectra of a reference carbonate CoCO{sub 3} implied that the bombardment-induced decomposition of CoC{sub 2}O{sub 4} gave rise to the formation of CoO-like and disordered CoCO{sub 3}-like phases.

Radiation-induced damage of membranes

International Nuclear Information System (INIS)

Yonei, Shuji

1977-01-01

An outline of membranous structure was stated, and radiation-induced damage of membranes were surveyed. By irradiation, permeability of membranes, especially passive transportation mechanism, was damaged, and glycoprotein in the surface layers of cells and the surface layer structures were changed. The intramembranous damage was induced by decrease of electrophoresis of nuclear mambranes and a quantitative change of cytochrome P450 of microsomal membranes of the liver, and peroxidation of membranous lipid and SH substitute damage of membranous protein were mentioned as the mechanism of membranous damage. Recovery of membranous damage depends on radiation dose and temperature, and membranous damage participates largely in proliferation death. (tsunoda, M.)

Type of Ground Surface during Plyometric Training Affects the Severity of Exercise-Induced Muscle Damage

Directory of Open Access Journals (Sweden)

Hamid Arazi

2016-03-01

Full Text Available The purpose of this study was to compare the changes in the symptoms of exercise-induced muscle damage from a bout of plyometric exercise (PE; 10 × 10 vertical jumps performed in aquatic, sand and firm conditions. Twenty-four healthy college-aged men were randomly assigned to one of three groups: Aquatic (AG, n = 8, Sand (SG, n = 8 and Firm (FG, n = 8. The AG performed PE in an aquatic setting with a depth of ~130 cm. The SG performed PE on a dry sand surface at a depth of 20 cm, and the FG performed PE on a 10-cm-thick wooden surface. Plasma creatine kinase (CK activity, delayed onset muscle soreness (DOMS, knee range of motion (KROM, maximal isometric voluntary contraction (MIVC of the knee extensors, vertical jump (VJ and 10-m sprint were measured before and 24, 48 and 72 h after the PE. Compared to baseline values, FG showed significantly (p < 0.05 greater changes in CK, DOMS, and VJ at 24 until 48 h. The MIVC decreased significantly for the SG and FG at 24 until 48 h post-exercise in comparison to the pre-exercise values. There were no significant (p > 0.05 time or group by time interactions in KROM. In the 10-m sprint, all the treatment groups showed significant (p < 0.05 changes compared to pre-exercise values at 24 h, and there were no significant (p > 0.05 differences between groups. The results indicate that PE in an aquatic setting and on a sand surface induces less muscle damage than on a firm surface. Therefore, training in aquatic conditions and on sand may be beneficial for the improvement of performance, with a concurrently lower risk of muscle damage and soreness.

Effect of Cavitation on Surface Damage of 16.7Cr-10Ni-2Mo Stainless Steel in Marine Environment

Energy Technology Data Exchange (ETDEWEB)

Chong, Sang-Ok; Han, Min-Su; Kim, Seong-Jong [Mokpo National Maritime University, Mokpo (Korea, Republic of)

2015-10-15

Stainless steel is generally known to have characteristics of excellent corrosion resistance and durability, but in a marine environment it can suffer from localized corrosion due to the breakdown of passivity film due to chloride ion in seawater. Furthermore, the damage behaviors are sped up under a cavitation environment because of complex damage from electrochemical corrosion and cavitation-erosion. In this study the characteristics of electrochemical corrosion and cavitation erosion behavior were evaluated on 16.7Cr-10Ni-2Mo stainless steel under a cavitation environment in natural seawater. The electrochemical experiments have been conducted at both static conditions and dynamic conditions inducing cavitation with different current density parameters. The surface morphology and damage behaviors were compared after the experiment. After the cavitation test with time variables morphological examinations on damaged specimens were analyzed by using a scanning electron microscope and a 3D microscope. the galvanostatic experiment gave a cleaner surface morphology presented with less damage depth at high current density regions. It is due to the effect of water cavitation peening under the cavitation condition. In the cavitation experiment, with amplitude of 30 μm and seawater temperature of 25 ℃, weight loss and cavitation-erosion damage depth were dramatically increased after 5 hours inducing cavitation.

Surface Damage Mechanism of Monocrystalline Si Under Mechanical Loading

Science.gov (United States)

Zhao, Qingliang; Zhang, Quanli; To, Suet; Guo, Bing

2017-03-01

Single-point diamond scratching and nanoindentation on monocrystalline silicon wafer were performed to investigate the surface damage mechanism of Si under the contact loading. The results showed that three typical stages of material removal appeared during dynamic scratching, and a chemical reaction of Si with the diamond indenter and oxygen occurred under the high temperature. In addition, the Raman spectra of the various points in the scratching groove indicated that the Si-I to β-Sn structure (Si-II) and the following β-Sn structure (Si-II) to amorphous Si transformation appeared under the rapid loading/unloading condition of the diamond grit, and the volume change induced by the phase transformation resulted in a critical depth (ductile-brittle transition) of cut (˜60 nm ± 15 nm) much lower than the theoretical calculated results (˜387 nm). Moreover, it also led to abnormal load-displacement curves in the nanoindentation tests, resulting in the appearance of elbow and pop-out effects (˜270 nm at 20 s, 50 mN), which were highly dependent on the loading/unloading conditions. In summary, phase transformation of Si promoted surface deformation and fracture under both static and dynamic mechanical loading.

Analysis of Boling's laser-damage morphology

International Nuclear Information System (INIS)

Sparks, M.S.

1980-01-01

Boling observed that his total-internal-reflection laser-damage sites in glass closely resembled the scattering cross section for small (ka << 1), perfectly conducting sphere and suggested that a very small plasma formed and grew to a larger size, still with ka << 1 satisfied. Even with ka = 1, for which the cross section is different from that observed, the scattered field still is too small to explain the damage in terms of constructive interference between the incident- and scattered fields. Furthermore, the characteristic shape of the scattering cross section that matches the damage patterns is for circular polarization or unpolarized light, in contrast to the experimental plane polarizations. Extending the ideas to include effects of the scattered field outside the glass, such as plasma formation, and to include the correct field (with interesting polarization, including longitudinal circuler polarization at certain distances from the surface) incident on the sphere may explain the experiments. Additional experiments and analysis would be useful to determine if the extended model is valid and to investigate related materials improvement, nondestructive testing, and the relation between laser damage, plasma initiation, and failure under stress, all initiated at small isolated spots

Effect of deep structure and surface layer (a) simulation study on the heavy damage belt of the 1995 Hyogoken Nanbu earthquake; Hado simulation wo mochiita `shinsai no obi` ni tsuite no kento

Energy Technology Data Exchange (ETDEWEB)

Feng, S; Ishikawa, K; Kaji, Y [Chuokaihatsu Corp., Tokyo (Japan)

1996-05-01

A simulation study was done to identify the causes for the so-called heavy damage belt observed as a result of the Hyogoken Nanbu Earthquake. This study determines distributions of the maximum amplitudes on the ground surfaces, and discusses the effects of deep structures and low-velocity surface layers, based on the simulation by the wave equation with the underground model of Higashinada-ku and its vicinity in the north-south direction, observed seismic records and artificial waves. The two-dimensional scalar wave equation is used for the analysis. The velocity structure model used for the simulation is established, based on the elastic wave seismic survey results. The focus function is drawn by expanding or contracting the time scale, using the seismic records at Kobe Port Island and artificial waves. The analysis results show that the damage belt coincides with the areas at which the focusing zone of the deep structure overlap the amplification zone in the low-velocity ground surfaces, where relative density is amplified 1.5 to 2 times. It is also observed that large peaks repeat 2 to 3 times on the time scale. 5 refs., 8 figs., 1 tab.

Combined Bulk and Surface Radiation Damage Effects at Very High Fluences in Silicon Detectors: Measurements and TCAD Simulations

CERN Document Server

Moscatelli, F; Morozzi, A; Mendicino, R; Dalla Betta, G F; Bilei, G M

2016-01-01

In this work we propose a new combined TCAD radiation damage modelling scheme, featuring both bulk and surface radiation damage effects, for the analysis of silicon detectors aimed at the High Luminosity LHC. In particular, a surface damage model has been developed by introducing the relevant parameters (NOX, NIT) extracted from experimental measurements carried out on p-type substrate test structures after gamma irradiations at doses in the range 10-500 Mrad(Si). An extended bulk model, by considering impact ionization and deep-level cross-sections variation, was included as well. The model has been validated through the comparison of the simulation findings with experimental measurements carried out at very high fluences (2×1016 1 MeV equivalent n/cm2) thus fostering the application of this TCAD approach for the design and optimization of the new generation of silicon detectors to be used in future HEP experiments.

CYGNSS Surface Wind Observations and Surface Flux Estimates within Low-Latitude Extratropical Cyclones

Science.gov (United States)

Crespo, J.; Posselt, D. J.

2017-12-01

The Cyclone Global Navigation Satellite System (CYGNSS), launched in December 2016, aims to improve estimates of surface wind speeds over the tropical oceans. While CYGNSS's core mission is to provide better estimates of surface winds within the core of tropical cyclones, previous research has shown that the constellation, with its orbital inclination of 35°, also has the ability to observe numerous extratropical cyclones that form in the lower latitudes. Along with its high spatial and temporal resolution, CYGNSS can provide new insights into how extratropical cyclones develop and evolve, especially in the presence of thick clouds and precipitation. We will demonstrate this by presenting case studies of multiple extratropical cyclones observed by CYGNSS early on in its mission in both Northern and Southern Hemispheres. By using the improved estimates of surface wind speeds from CYGNSS, we can obtain better estimates of surface latent and sensible heat fluxes within and around extratropical cyclones. Surface heat fluxes, driven by surface winds and strong vertical gradients of water vapor and temperature, play a key role in marine cyclogenesis as they increase instability within the boundary layer and may contribute to extreme marine cyclogenesis. In the past, it has been difficult to estimate surface heat fluxes from space borne instruments, as these fluxes cannot be observed directly from space, and deficiencies in spatial coverage and attenuation from clouds and precipitation lead to inaccurate estimates of surface flux components, such as surface wind speeds. While CYGNSS only contributes estimates of surface wind speeds, we can combine this data with other reanalysis and satellite data to provide improved estimates of surface sensible and latent heat fluxes within and around extratropical cyclones and throughout the entire CYGNSS mission.

Myocardial perfusion alterations observed months after radiotherapy are related to the cellular damage

Energy Technology Data Exchange (ETDEWEB)

Dogan, I.; Sonmez, B. [Karadeniz Technical Univ., Trabzon (Turkey). Dept. of Nuclear Medicine; Sezen, O.; Zengin, A.Y.; Bahat, Z. [Karadeniz Technical Univ., Trabzon (Turkey). Dept. of Radiation Oncology; Yenilmez, E.; Yulug, E. [Karadeniz Technical Univ., Trabzon (Turkey). Dept. of Histology and Embryology; Abidin, I. [Karadeniz Technical Univ., Trabzon (Turkey). Dept. of Biophysics

2010-07-01

Myocardial perfusion scintigraphy (MPS) is one of the widely used tools to follow developing radiation-induced heart disease (RIHD). But the clinical significance of MPS defects has not been fully understood. We have investigated the biodistribution alterations related to perfusion defects following radiotherapy (RT) and showed coexisting morphological changes. Animals, methods: A total of 18 Wistar rats were divided into three groups (1 control and 2 irradiated groups). A single cardiac 20 Gy radiation dose was used to induce long term cardiac defects. Biodistribution studies with technetium ({sup 99m}Tc) sestamibi and histological evaluations were performed 4 and 6 months after irradiation. The percent radioactivity (%ID/g) was calculated for each heart. For determination of the myocardial damage, positive apoptotic cardiomyocytes, myocardial cell degeneration, myocardial fibrosis, vascular damage and ultrastructural structures were evaluated. Results: Six months after treatment, a significant drop of myocardial uptake was observed (p < 0.05). Irradiation-induced apoptosis rose within the first 4 months after radiation treatment and were stayed elevated until the end of the observation period (p < 0.05). Also, the irradiation has induced myocardial degeneration, perivascular and interstitial fibrosis in the heart at the end of six and four months (p < 0.01). The severity and extent of myocardial injury has became more evident at the end of six month (p < 0.05). At ultrastructural level, prominent changes have been observed in the capillary endothelial and myocardial cells. Conclusion: Our findings suggest that the reduced rest myocardial perfusion, occuring months after the radiation, indicates a serious myocard tissue damage which is characterized by myocardial degeneration and fibrosis. (orig.)

Myocardial perfusion alterations observed months after radiotherapy are related to the cellular damage

International Nuclear Information System (INIS)

Dogan, I.; Sonmez, B.; Sezen, O.; Zengin, A.Y.; Bahat, Z.; Yenilmez, E.; Yulug, E.; Abidin, I.

2010-01-01

Myocardial perfusion scintigraphy (MPS) is one of the widely used tools to follow developing radiation-induced heart disease (RIHD). But the clinical significance of MPS defects has not been fully understood. We have investigated the biodistribution alterations related to perfusion defects following radiotherapy (RT) and showed coexisting morphological changes. Animals, methods: A total of 18 Wistar rats were divided into three groups (1 control and 2 irradiated groups). A single cardiac 20 Gy radiation dose was used to induce long term cardiac defects. Biodistribution studies with technetium ( 99m Tc) sestamibi and histological evaluations were performed 4 and 6 months after irradiation. The percent radioactivity (%ID/g) was calculated for each heart. For determination of the myocardial damage, positive apoptotic cardiomyocytes, myocardial cell degeneration, myocardial fibrosis, vascular damage and ultrastructural structures were evaluated. Results: Six months after treatment, a significant drop of myocardial uptake was observed (p < 0.05). Irradiation-induced apoptosis rose within the first 4 months after radiation treatment and were stayed elevated until the end of the observation period (p < 0.05). Also, the irradiation has induced myocardial degeneration, perivascular and interstitial fibrosis in the heart at the end of six and four months (p < 0.01). The severity and extent of myocardial injury has became more evident at the end of six month (p < 0.05). At ultrastructural level, prominent changes have been observed in the capillary endothelial and myocardial cells. Conclusion: Our findings suggest that the reduced rest myocardial perfusion, occuring months after the radiation, indicates a serious myocard tissue damage which is characterized by myocardial degeneration and fibrosis. (orig.)

Damage Maps of Veneered Zirconia under Simulated Mastication

Science.gov (United States)

Kim, Jae-Won; Kim, Joo-Hyung; Janal, Malvin N.; Zhang, Yu

2016-01-01

Zirconia based restorations often fracture from chipping and/or delamination of the porcelain veneers. We hypothesize that veneer chipping/delamination is a result of the propagation of near-contact induced partial cone cracks on the occlusal surface under mastication. Masticatory loading involves the opposing tooth sliding along the cuspal inner incline surface with an applied biting force. To test this hypothesis, flat porcelain veneered zirconia plates were cemented to dental composites and cyclically loaded (contact–slide–liftoff) at an inclination angle as a simplified model of zirconia based restorations under occlusion. In the light of in-situ observation of damage evolution in a transparent glass/zirconia/polycarbonate trilayer, postmortem damage evaluation of porcelain/zirconia/composite trilayers using a sectioning technique revealed that deep penetrating occlusal surface partial cone fracture is the predominant fracture mode of porcelain veneers. Clinical relevance is discussed. PMID:19029080

Surface Observations from Punta Arenas, Chile

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Surface Observations from Punta Arenas, in extreme southern Chile. WMO station ID 85934. Period of record 1896-1954. The original forms were scanned at the Museo...

Improved laser damage threshold performance of calcium fluoride optical surfaces via Accelerated Neutral Atom Beam (ANAB) processing

Science.gov (United States)

Kirkpatrick, S.; Walsh, M.; Svrluga, R.; Thomas, M.

2015-11-01

Optics are not keeping up with the pace of laser advancements. The laser industry is rapidly increasing its power capabilities and reducing wavelengths which have exposed the optics as a weak link in lifetime failures for these advanced systems. Nanometer sized surface defects (scratches, pits, bumps and residual particles) on the surface of optics are a significant limiting factor to high end performance. Angstrom level smoothing of materials such as calcium fluoride, spinel, magnesium fluoride, zinc sulfide, LBO and others presents a unique challenge for traditional polishing techniques. Exogenesis Corporation, using its new and proprietary Accelerated Neutral Atom Beam (ANAB) technology, is able to remove nano-scale surface damage and particle contamination leaving many material surfaces with roughness typically around one Angstrom. This surface defect mitigation via ANAB processing can be shown to increase performance properties of high intensity optical materials. This paper describes the ANAB technology and summarizes smoothing results for calcium fluoride laser windows. It further correlates laser damage threshold improvements with the smoothing produced by ANAB surface treatment. All ANAB processing was performed at Exogenesis Corporation using an nAccel100TM Accelerated Particle Beam processing tool. All surface measurement data for the paper was produced via AFM analysis on a Park Model XE70 AFM, and all laser damage testing was performed at Spica Technologies, Inc. Exogenesis Corporation's ANAB processing technology is a new and unique surface modification technique that has demonstrated to be highly effective at correcting nano-scale surface defects. ANAB is a non-contact vacuum process comprised of an intense beam of accelerated, electrically neutral gas atoms with average energies of a few tens of electron volts. The ANAB process does not apply mechanical forces associated with traditional polishing techniques. ANAB efficiently removes surface

Observations on the effects of acid rain treatment on needle surfaces of scots pine and Norway spruce seedlings

International Nuclear Information System (INIS)

Turunen, M.; Huttunen, S.; Back, J.

1994-01-01

Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst.) seedlings were subjected to acid rain treatment at pH 3, pH 4 and pH 7 in a field experiment during 1986-1989. SEM+EDS, TEM, and measurements of wax quantity were used to detect changes in needle surfaces. After 5 weeks at pH 3 and pH 4 acid rain treatment, CaSO 4 -crystallites were observed on visibly undamaged pine and spruce needle surfaces. Direct acid rain damage in conjunction with CaSO 4 -crystallites was observed only occasionally in wax structures. Two-month-old pine needles had 50% less wax in early August after exposure at pH 3 and pH 4 than water controls. The occurrence of CaSO 4 -crystallites on acid rain-treated needle surfaces, and more abundant deposition of Ca oxalate crystallites in the inner walls of epi- and hypodermal cells could be involved with acid rain-induced calcium leaching. Calcium sulphate is probably a result of the disturbed wax and cuticle biosynthesis resulting in undeveloped, permeable cuticles. At the end of experiment, no CaSO 4 -crystallites were seen on needle surfaces. Soil analysis revealed an increase in the soluble Ca concentrations at pH 3. (orig.)

Laser-Induced Damage Growth on Larger-Aperture Fused Silica Optical Components at 351 nm

International Nuclear Information System (INIS)

Wan-Qing, Huang; Wei, Han; Fang, Wang; Yong, Xiang; Fu-Quan, Li; Bin, Feng; Feng, Jing; Xiao-Feng, Wei; Wan-Guo, Zheng; Xiao-Min, Zhang

2009-01-01

Laser-induced damage is a key lifetime limiter for optics in high-power laser facility. Damage initiation and growth under 351 nm high-fluence laser irradiation are observed on larger-aperture fused silica optics. The input surface of one fused silica component is damaged most severely and an explanation is presented. Obscurations and the area of a scratch on it are found to grow exponentially with the shot number. The area of damage site grows linearly. Micrographs of damage sites support the micro-explosion damage model which could be used to qualitatively explain the phenomena

Lightning climatology over Jakarta, Indonesia, based on long-term surface operational, satellite, and campaign observations

Science.gov (United States)

Mori, Shuichi; Wu, Peiming; Yamanaka, Manabu D.; Hattori, Miki; Hamada, Jun-Ichi; Arbain, Ardhi A.; Lestari, Sopia; Sulistyowati, Reni; Syamsudin, Fadli

2016-04-01

Lightning frequency over Indonesian Maritime Continent (MC) is quite high (Petersen and Rutledge 2001, Christian et al. 2003, Takayabu 2006, etc). In particular, Bogor (south of Jakarta, west Jawa) had 322 days of lightning in one year (Guinness Book in 1988). Lightning causes serious damage on nature and society over the MC; forest fore, power outage, inrush/surge currents on many kinds of electronics. Lightning climatology and meso-scale characteristics of thunderstorm over the MC, in particular over Jakarta, where social damage is quite serious, were examined. We made Statistical analysis of lightning and thunderstorm based on TRMM Lightning Image Sensor (LIS) and Global Satellite Mapping of Precipitation (GSMaP) together with long-term operational surface observation data (SYNOP) in terms of diurnal, intraseasonal, monsoonal, and interannual variations. In addition, we carried out a campaign observation in February 2015 in Bogor to obtain meso-scale structure and dynamics of thunderstorm over Jakarta to focus on graupel and other ice phase particles inside by using an X-band dual-polarimetric (DP) radar. Recently, Virts et al. (2013a, b) showed comprehensive lightning climatology based on the World Wide Lightning Location Network (WWLLN). However, they also reported problems with its detection efficiency (Japan Society for the Promotion of Science (JSPS) KAKENHI (Grants-in-Aid for Scientific Research) grant number 25350515 and the Japan Aerospace Exploration Agency (JAXA) 7th Research Announcement (RA).

Land-Surface-Atmosphere Coupling in Observations and Models

Directory of Open Access Journals (Sweden)

Alan K Betts

2009-07-01

Full Text Available The diurnal cycle and the daily mean at the land-surface result from the coupling of many physical processes. The framework of this review is largely conceptual; looking for relationships and information in the coupling of processes in models and observations. Starting from the surface energy balance, the role of the surface and cloud albedos in the shortwave and longwave fluxes is discussed. A long-wave radiative scaling of the diurnal temperature range and the night-time boundary layer is summarized. Several aspects of the local surface energy partition are presented: the role of soilwater availability and clouds; vector methods for understanding mixed layer evolution, and the coupling between surface and boundary layer that determines the lifting condensation level. Moving to larger scales, evaporation-precipitation feedback in models is discussed; and the coupling of column water vapor, clouds and precipitation to vertical motion and moisture convergence over the Amazon. The final topic is a comparison of the ratio of surface shortwave cloud forcing to the diabatic precipitation forcing of the atmosphere in ERA-40 with observations.

Evaluation of surface fractal dimension of carbon for plasma-facing material damaged by hydrogen plasma

International Nuclear Information System (INIS)

Nishino, Nobuhiro

1997-01-01

The surface structure of the plasma facing materials (PFM) changes due to plasma-surface interaction in a nuclear fusion reactor. Usually B 4 C coated graphite block are used as PFM. In this report, the surface fractal was applied to study the surface structure of plasma-damaged PFM carbon. A convenient flow-type adsorption apparatus was developed to evaluate the surface fractal dimension of materials. Four branched alkanol molecules with different apparent areas were used as the probe adsorbates. The samples used here were B 4 C coated isotopic graphite which were subjected to hydrogen plasma for various periods of exposure. The monolayer capacities of these samples for alkanols were determined by applying BET theory. The surface fractal dimension was calculated using the monolayer capacities and molecular areas for probe molecules and was found to increase from 2 to 3 with the plasma exposure time. (author)

Biconvex intraocular lenses and Nd:YAG capsulotomy: Experimental comparison of surface damage with different poly(methyl methacrylate) formulations

Energy Technology Data Exchange (ETDEWEB)

Downing, J.E.; Alberhasky, M.T. (Greenview Hospital, Bowling Green, KY (USA))

1990-11-01

Biconvex posterior chamber lenses have optical advantages and decrease the risk of capsular opacification, but they are more likely to be pitted during ND:YAG capsulotomy because of apposition of the lens to the capsule. This study reports the likelihood of surface damage to different formulations of poly(methyl methacrylate) at the energy levels required to open posterior capsules. Molded lenses are more easily damaged than higher molecular weight lathe-cut materials (P less than .01), as expected. However, by keeping energy output low, even injection-molded lenses showed minimal damage, with mean pit size 39 +/- 39 microns at 1 mJ. By using a converging contact lens, low power, and keeping the focus behind the capsule, damage to all materials tested should be clinically insignificant.

Evaluation of Bulk and Surface Radiation Damage of Silicon Sensors for the ATLAS Upgrade

CERN Document Server

Mikeštíková, Marcela; Št'astný, Jan

2015-01-01

The electrical characteristics of different types of end-cap miniature n + -in- p strip sensors, ATLAS12A, were evaluated in Institute of Physics in Prague before and after proton and gamma irradiation. We report here on the bulk damage aspects, including the increase of leakage current and evaluation of the full depletion voltage and the surface damage, including the decrease of inter-strip resistance, changes in inter-strip capacitance and the effectiveness of punch-through protection structure. It was verified that different geometries of end-cap sensors do not influence their stability; the sensors should provide acceptable strip isolation and n ew gate PTP structure functions well even at the highest tested proton fluence 2× 10 15 n eq / cm 2

Damage detection in high-rise buildings using damage-induced rotations

International Nuclear Information System (INIS)

Sung, Seung Hun; Jung, Ho Youn; Lee, Jung Hoon; Jung, Hyung Jo

2016-01-01

In this paper, a new damage-detection method based on structural vibration is proposed. The essence of the proposed method is the detection of abrupt changes in rotation. Damage-induced rotation (DIR), which is determined from the modal flexibility of the structure, initially occurs only at a specific damaged location. Therefore, damage can be localized by evaluating abrupt changes in rotation. We conducted numerical simulations of two damage scenarios using a 10-story cantilever-type building model. Measurement noise was also considered in the simulation. We compared the sensitivity of the proposed method to localize damage to that of two conventional modal-flexibility-based damage-detection methods, i.e., uniform load surface (ULS) and ULS curvature. The proposed method was able to localize damage in both damage scenarios for cantilever structures, but the conventional methods could not

Damage detection in high-rise buildings using damage-induced rotations

International Nuclear Information System (INIS)

Sung, Seung Hoon; Jung, Ho Youn; Lee, Jung Hoon; Jung, Hyung Jo

2014-01-01

In this paper, a new damage-detection method based on structural vibration is proposed. The essence of the proposed method is the detection of abrupt changes in rotation. Damage-induced rotation (DIR), which is determined from the modal flexibility of the structure, initially occurs only at a specific damaged location. Therefore, damage can be localized by evaluating abrupt changes in rotation. We conducted numerical simulations of two damage scenarios using a 10-story cantilever-type building model. Measurement noise was also considered in the simulation. We compared the sensitivity of the proposed method to localize damage to that of two conventional modal-flexibility-based damage-detection methods, i.e., uniform load surface (ULS) and ULS curvature. The proposed method was able to localize damage in both damage scenarios for cantilever structures, but the conventional methods could not.

Investigation of plasma etch damage to porous oxycarbosilane ultra low-k dielectric

International Nuclear Information System (INIS)

Bruce, R L; Engelmann, S; Purushothaman, S; Volksen, W; Frot, T J; Magbitang, T; Dubois, G; Darnon, M

2013-01-01

There has been much interest recently in porous oxycarbosilane (POCS)-based materials as the ultra-low k dielectric (ULK) in back-end-of-line (BEOL) applications due to their superior mechanical properties compared to traditional organosilicate-based ULK materials at equivalent porosity and dielectric constant. While it is well known that plasma etching and strip processes can cause significant damage to ULK materials in general, little has been reported about the effect of plasma damage to POCS as the ULK material. We investigated the effect of changing the gas discharge chemistry and substrate bias in the dielectric trench etch and also the subsequent effect of the cap-open etch on plasma damage to POCS during BEOL integration. Large differences in surface roughness and damage behaviour were observed by changing the fluorocarbon depositing conditions. These damage behaviour trends will be discussed and potential rationalizations offered based on the formation of pits and craters at the etch front that lead to surface roughness and microtrenching. (paper)

Core damage frequency observations and insights of LWRs based on the IPEs

Energy Technology Data Exchange (ETDEWEB)

Dingman, S.E.; Camp, A.L. [Sandia National Labs., Albuquerque, NM (United States); Drouin, M.T. [and others

1995-04-01

Seventy-eight plants are expected to submit Individual Plant Examinations (IPEs) for severe accident vulnerabilities to the US Nuclear Regulatory Commission (NRC). The majority of the plants have elected to perform full Level 1 probabilistic risk assessments (PRAs) to meet the intent of the IPEs. Because of this, it is possible to compare the results from the IPE submittals to determine general observations and {open_quotes}lessons learned{close_quotes} from the IPEs. The IPE Insights Program is performing this evaluation, and preliminary results are presented in this paper. The core damage frequency and core damage sequences are identified and compared for pressurized water reactors and boiling water reactors. Examination of the results indicates that variations among plant results are due to a combination of actual plant design/operational features and analysis approaches. The findings are consistent with previous NRC studies, such as WASH-1400 and NUREG-1150.

Core damage frequency observations and insights of LWRs based on the IPEs

International Nuclear Information System (INIS)

Dingman, S.E.; Camp, A.L.; Drouin, M.T.; Kolaczkowski, A.; Darby, J.; LaChance, J.L.; Yakle, J.

1995-01-01

Seventy-eight plants are expected to submit Individual Plant Examinations (IPEs) for severe accident vulnerabilities to the U.S. Nuclear Regulatory Commission (NRC). The majority of the plants have elected to perform full Level 1 probabilistic risk assessments (PRAs) to meet the intent of the IPES. Because of this, it is possible to compare the results from the IPE submittals to determine general observations and open-quotes lessons learnedclose quotes from the IPES. The IPE Insights Program is performing this evaluation, and preliminary results are presented in this paper. The core damage frequency and core damage sequences are identified and compared for pressurized water reactors and boiling water reactors. Examination of the results indicates that variations among plant results are due to a combination of actual plant design/operational features and analysis approaches. The findings are consistent with previous NRC studies, such as WASH-1400 and NUREG-1 150

Detection of a milling-induced surface damage by the magnetic Barkhausen noise

Science.gov (United States)

Stupakov, A.; Neslušan, M.; Perevertov, O.

2016-07-01

The potential of the magnetic Barkhausen noise method for a non-destructive evaluation of the steel surface damage cased by milling was comprehensively investigated. A typical bearing steel was heat treated to three different hardnesses and then machined using the cutting tools with different degrees of the flank wear. The magnetic low-frequency measurements with a high reading depth were performed using a unique laboratory system providing a full control of the magnetization process. The high-frequency measurements were performed using a commercial Rollscan device. To study the induced magnetic anisotropy, the measurements were performed in two magnetization directions. In the feeding direction, the Barkhausen noise profiles showed a second high-field peak ascribed to an induced hardened surface layer, a so-called white layer. The most reliable results were obtained with the controlled waveform of the surface magnetic field measured directly by Hall sensors. In the perpendicular rotation direction, formation of the preferentially oriented matrix resulted in an enormously high Barkhausen noise activity. Based on these results, new magnetic parameters were proposed for the non-destructive evaluation of the white layer formation.

Automated analysis of damages for radiation in plastics surfaces; Analisis automatizado de danos por radiacion en superficies plasticas

Energy Technology Data Exchange (ETDEWEB)

Andrade, C; Camacho M, E; Tavera, L; Balcazar, M [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

1990-02-15

Analysis of damages done by the radiation in a polymer characterized by optic properties of polished surfaces, of uniformity and chemical resistance that the acrylic; resistant until the 150 centigrade grades of temperature, and with an approximate weight of half of the glass. An objective of this work is the development of a method that analyze in automated form the superficial damages induced by radiation in plastic materials means an images analyst. (Author)

Combined effect of bulk and surface damage on strip insulation properties of proton irradiated n$^{+}$-p silicon strip sensors

CERN Document Server

Dalal, R; Ranjan, K; Moll, M; Elliott-Peisert, A

2014-01-01

Silicon sensors in next generation hadron colliders willface a tremendously harsh radiation environment. Requirement tostudy rarest reaction channels with statistical constraints hasresulted in a huge increment in radiation flux, resulting in bothsurface damage and bulk damage. For sensors which are used in acharged hadron environment, both of these degrading processes takeplace simultaneously. Recently it has been observed in protonirradiated n$^{+}$-p Si strip sensors that n$^{+}$ strips had a goodinter-strip insulation with low values of p-spray and p-stop dopingdensities which is contrary to the expected behaviour from thecurrent understanding of radiation damage. In this work a simulationmodel has been devised incorporating radiation damage to understandand provide a possible explanation to the observed behaviour ofirradiated sensors.

Effect of temperature on surface error and laser damage threshold for self-healing BK7 glass.

Science.gov (United States)

Wang, Chu; Wang, Hongxiang; Shen, Lu; Hou, Jing; Xu, Qiao; Wang, Jian; Chen, Xianhua; Liu, Zhichao

2018-03-20

Cracks caused during the lapping and polishing process can decrease the laser-induced damage threshold (LIDT) of the BK7 glass optical elements, which would shorten the lifetime and limit the output power of the high-energy laser system. When BK7 glass is heated under appropriate conditions, the surface cracks can exhibit a self-healing phenomenon. In this paper, based on thermodynamics and viscous fluid mechanics theory, the mechanisms of crack self-healing are explained. The heat-healing experiment was carried out, and the effect of water was analyzed. The multi-spatial-frequency analysis was used to investigate the effect of temperature on surface error for self-healing BK7 glass, and the lapped BK7 glass specimens before and after heat healing were detected by an interferometer and atomic force microscopy. The low-spatial-frequency error was analyzed by peak to valley and root mean square, the mid-spatial-frequency error was analyzed by power spectral density, and the high-spatial-frequency error was analyzed by surface roughness. The results showed that the optimal heating temperature for BK7 was 450°C, and when the heating temperature was higher than the glass transition temperature (555°C), the surface quality decreased a lot. The laser damage test was performed, and the specimen heated at 450°C showed an improvement in LIDT.

Damage at a tungsten surface induced by impacts of self-atoms

Energy Technology Data Exchange (ETDEWEB)

Wu, Yong [Data Center for High Energy Density Physics, Institute of Applied Physics and, Computational Mathematics, P. O. Box 8009, Beijing 100088 (China); Krstic, Predrag, E-mail: predrag.krstic@stonybrook.edu [Institute for Advanced Computational Science, Stony Brook University, Stony Brook, NY 11794-5250 (United States); Zhou, Fu Yang [College of Material Sciences and Optoelectronic Technology, University of the Chinese Academy of Sciences, P. O. Box 4588, Beijing 100049 (China); Meyer, Fred [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6372 (United States)

2015-12-15

We study evolution of the surface defects of a 300 K tungsten surface due to the cumulative impact of 0.25–10 keV self-atoms. The simulation is performed by molecular dynamics with bond-order Tersoff-form potentials. At all studied impact energies the computation shows strong defect-recombination effect of both created Frenkel pairs as well as recombination of the implanted atoms with the vacancies created by the sputtering. This leads to a saturation of the cumulative count of vacancies, evident at energies below 2 keV, as long as the implantation per impact atom exceeds sputtering and to a saturation of the interstitial count when production of the sputtered particles per impact atom becomes larger than 1 (in the energy range 2-4 keV). The number of cumulative defects is fitted as functions of impact fluence and energy, enabling their analytical extrapolation outside the studied range of parameters. - Highlights: • We calculated cumulative creation of defects in tungsten by self-atom impact. • At some energies, the defect count saturate with increasing damage dose. • The defects are accumulated in the first few layers of the tungsten surface. • The interstitials are formed predominantly as adatoms.

Fatigue damage mechanisms in short fiber reinforced PBT+PET GF30

International Nuclear Information System (INIS)

Klimkeit, B.; Castagnet, S.; Nadot, Y.; Habib, A. El; Benoit, G.; Bergamo, S.; Dumas, C.; Achard, S.

2011-01-01

Research highlights: → Final macroscopic cracking only affects the few last percent of the lifetime → Classical approach based on fracture surface observation is not sufficient to characterize micro-mechanisms → Different techniques (scanning electron microscopy, replica technique, infra-red imaging) are compared to the macroscopic mechanical behavior evolution (stiffness, viscous damping, ratcheting effect) → The influence of surrounding fibers on some observed damage processes is being evidenced for the first time. - Abstract: The fatigue damage of a glass-reinforced PolyButylene Terephthalate and PolyEthylene Terephthalate with the fiber volume fraction of 30% (PBT+PET GF30) is investigated by means of various techniques. Fatigue tests at R = 0.1 are carried out on dogbone specimens and tubular specimens with different fiber orientations. The macroscopic evolution of the material behavior is evaluated and fatigue damage mechanisms are observed with a replica technique, Infrared imaging and scanning electron microscopy. A fatigue damage scenario is finally proposed. It is shown that the propagation of a single macroscopic crack is not the major fatigue mechanism under fatigue loading. Damage is spatially distributed in the material and the classical circular crack at the end of the fiber is confirmed as the based fatigue mechanisms. It is also shown that the damage observed alongside the fibers is related to spatial distribution of fiber rather than stress distribution around one single fiber.

Advancing land surface model development with satellite-based Earth observations

Science.gov (United States)

Orth, Rene; Dutra, Emanuel; Trigo, Isabel F.; Balsamo, Gianpaolo

2017-04-01

The land surface forms an essential part of the climate system. It interacts with the atmosphere through the exchange of water and energy and hence influences weather and climate, as well as their predictability. Correspondingly, the land surface model (LSM) is an essential part of any weather forecasting system. LSMs rely on partly poorly constrained parameters, due to sparse land surface observations. With the use of newly available land surface temperature observations, we show in this study that novel satellite-derived datasets help to improve LSM configuration, and hence can contribute to improved weather predictability. We use the Hydrology Tiled ECMWF Scheme of Surface Exchanges over Land (HTESSEL) and validate it comprehensively against an array of Earth observation reference datasets, including the new land surface temperature product. This reveals satisfactory model performance in terms of hydrology, but poor performance in terms of land surface temperature. This is due to inconsistencies of process representations in the model as identified from an analysis of perturbed parameter simulations. We show that HTESSEL can be more robustly calibrated with multiple instead of single reference datasets as this mitigates the impact of the structural inconsistencies. Finally, performing coupled global weather forecasts we find that a more robust calibration of HTESSEL also contributes to improved weather forecast skills. In summary, new satellite-based Earth observations are shown to enhance the multi-dataset calibration of LSMs, thereby improving the representation of insufficiently captured processes, advancing weather predictability and understanding of climate system feedbacks. Orth, R., E. Dutra, I. F. Trigo, and G. Balsamo (2016): Advancing land surface model development with satellite-based Earth observations. Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-628

Haertel's turbidity test and extraction of conifer needles by benzene as methods for the determination of smoke-induced damage

Energy Technology Data Exchange (ETDEWEB)

Materna, J; Hrncirova, L

1960-01-01

The applicability of the Haertel turbidity test to the assessment of smoke damage to conifers is based on the observation that needles from smoke damage to conifers is based on the observation that needles from smoke-damaged areas eliminate less wax than undamaged needles. Of the various organic solvent and extraction methods tested, best results were obtained by a half-hour extraction of the wax from the needle surface with cold benzene. The evaporation residue from this extraction method contained only traces of components from the inside of the needles; microscopic examination of the surface of the needles revealed that all wax was removed from the needle surface fissures. Comparison of wax quantities extracted from needles from smoke-damage areas with those from healthy needles and comparison of wax yields from areas which suffered different degrees of smoke damage confirmed that higher wax yields are obtained from healthy than from smoke-damaged needles. Comparison with results of turbidity tests disclosed that benzene extraction yields decreased with increasing turbidity test values, indicating that increased turbidity of smoke-damaged needles is not caused by wax. In the Haertel test extract, silicon, calcium, magnesium, phosphorus, potassium, sulfur, iron, nitrogenous substances, tannin, glycides, and waxes were found. It is as yet unresolved which substances contribute to increased turbidity from smoke damage.

Development of a Graphical User Interface to Visualize Surface Observations

Energy Technology Data Exchange (ETDEWEB)

Buckley, R.L.

1998-07-13

Thousands of worldwide observing stations provide meteorological information near the earth's surface as often as once each hour. This surface data may be plotted on geographical maps to provide the meteorologist useful information regarding weather patterns for a region of interest. This report describes the components and applications of a graphical user interface which have been developed to visualize surface observations at any global location and time of interest.

Subsurface damage mechanism of high speed grinding process in single crystal silicon revealed by atomistic simulations

International Nuclear Information System (INIS)

Li, Jia; Fang, Qihong; Zhang, Liangchi; Liu, Youwen

2015-01-01

Highlights: • Molecular dynamic model of nanoscale high speed grinding of silicon workpiece has been established. • The effect of grinding speed on subsurface damage and grinding surface integrity by analyzing the chip, dislocation movement, and phase transformation during high speed grinding process are thoroughly investigated. • Subsurface damage is studied by the evolution of surface area at first time for more obvious observation on transition from ductile to brittle. • The hydrostatic stress and von Mises stress by the established analytical model are studied subsurface damage mechanism during nanoscale grinding. - Abstract: Three-dimensional molecular dynamics (MD) simulations are performed to investigate the nanoscale grinding process of single crystal silicon using diamond tool. The effect of grinding speed on subsurface damage and grinding surface integrity by analyzing the chip, dislocation movement, and phase transformation are studied. We also establish an analytical model to calculate several important stress fields including hydrostatic stress and von Mises stress for studying subsurface damage mechanism, and obtain the dislocation density on the grinding subsurface. The results show that a higher grinding velocity in machining brittle material silicon causes a larger chip and a higher temperature, and reduces subsurface damage. However, when grinding velocity is above 180 m s −1 , subsurface damage thickness slightly increases because a higher grinding speed leads to the increase in grinding force and temperature, which accelerate dislocation nucleation and motion. Subsurface damage is studied by the evolution of surface area at first time for more obvious observation on transition from ductile to brittle, that provides valuable reference for machining nanometer devices. The von Mises stress and the hydrostatic stress play an important role in the grinding process, and explain the subsurface damage though dislocation mechanism under high

Radiation damage in dielectric and semiconductor single crystals (direct observation)

CERN Document Server

Adawi, M A; Varichenko, V S; Zaitsev, A M

1998-01-01

The surfaces of boron-doped synthetic and natural diamonds have been investigated by using the scanning tunnelling microscope (STM) and the scanning electronic microscope (SEM) before and after irradiating the samples with sup 4 sup 0 Ar (25 MeV), sup 8 sup 4 Kr (210 MeV) and sup 1 sup 2 sup 5 Xe (124 MeV) ions. The structures observed after irradiation showed craters with diameters ranging from 3 nm up to 20 nm, which could be interpreted as single ion tracks and multiple hits of ions at the nearest positions of the surface. In the case of argon ion irradiation, the surface was found to be completely amorphous, but after xenon irradiation one could see parts of surface without amorphism. This can be explained by the influence of high inelastic energy losses. The energy and temperature criteria of crater formation as a result of heavy ion irradiation are introduced.

Complex damage distribution behaviour in cobalt implanted rutile TiO2 (1 1 0) lattice

Science.gov (United States)

Joshi, Shalik Ram; Padmanabhan, B.; Chanda, Anupama; Ojha, Sunil; Kanjilal, D.; Varma, Shikha

2017-11-01

The present work investigates the radiation damage, amorphization and structural modifications that are produced by ion-solid interactions in TiO2 crystals during 200 keV Cobalt ion implantation. RBS/C and GIXRD have been utilized to evaluate the damage in the host lattice as a function of ion fluence. Multiple scattering formalism has been applied to extract the depth dependent damage distributions in TiO2(1 1 0). The results have been compared with the MC simulations performed using SRIM-2013. RBS/C results delineate a buried amorphous layer at a low fluence. Surprisingly, ion induced dynamic activation produces a recovery in this damage at higher fluences. This improvement interestingly occurs only in deep regions (60-300 nm) where a systematic lowering in damage with fluence is observed. Formation of Co-Ti-O phases and generation of stress in TiO2 lattice can also be responsible for this improvement in deep regions. In contrast, surface region (0-60 nm) indicates a gradual increase in damage with fluence. Such a switch in the damage behavior creates a cross point in damage profiles at 60 nm. Surface region is a sink of vacancies whereas deep layers are interstitial rich. However, these regions are far separated from each other resulting in an intermediate (100-150 nm) region with a significant dip (valley) in damage which can be characterized by enhanced recombination of point defects. The damage profiles thus indicate a very complex behavior. MC simulations, however, present very different results. They depict a damage profile that extends to a depth of only 150 nm, which is only about half of the damage- width observed here via RBS/C. Moreover, MC simulations do not indicate presence of any valley like structure in the damage profile. The complex nature of damage distribution observed here via RBS/C may be related to the high ionic nature of the chemical bonds in the TiO2 lattice.

Quantifying Surface Energy Flux Estimation Uncertainty Using Land Surface Temperature Observations

Science.gov (United States)

French, A. N.; Hunsaker, D.; Thorp, K.; Bronson, K. F.

2015-12-01

Remote sensing with thermal infrared is widely recognized as good way to estimate surface heat fluxes, map crop water use, and detect water-stressed vegetation. When combined with net radiation and soil heat flux data, observations of sensible heat fluxes derived from surface temperatures (LST) are indicative of instantaneous evapotranspiration (ET). There are, however, substantial reasons LST data may not provide the best way to estimate of ET. For example, it is well known that observations and models of LST, air temperature, or estimates of transport resistances may be so inaccurate that physically based model nevertheless yield non-meaningful results. Furthermore, using visible and near infrared remote sensing observations collected at the same time as LST often yield physically plausible results because they are constrained by less dynamic surface conditions such as green fractional cover. Although sensitivity studies exist that help identify likely sources of error and uncertainty, ET studies typically do not provide a way to assess the relative importance of modeling ET with and without LST inputs. To better quantify model benefits and degradations due to LST observational inaccuracies, a Bayesian uncertainty study was undertaken using data collected in remote sensing experiments at Maricopa, Arizona. Visible, near infrared and thermal infrared data were obtained from an airborne platform. The prior probability distribution of ET estimates were modeled using fractional cover, local weather data and a Penman-Monteith mode, while the likelihood of LST data was modeled from a two-source energy balance model. Thus the posterior probabilities of ET represented the value added by using LST data. Results from an ET study over cotton grown in 2014 and 2015 showed significantly reduced ET confidence intervals when LST data were incorporated.

Study of surface damage on cell envelope assessed by AFM and flow cytometry of Lactobacillus plantarum exposed to ethanol and dehydration.

Science.gov (United States)

Bravo-Ferrada, B M; Gonçalves, S; Semorile, L; Santos, N C; Tymczyszyn, E E; Hollmann, A

2015-06-01

In this work, we evaluated freeze-drying damage at the surface level of oenological strain Lactobacillus plantarum UNQLp155, as well as its ability to grow in a synthetic wine with and without pre-acclimation. Damage on cell surface was studied by flow cytometry, zeta potential and atomic force microscopy, and cell survival was analysed by plate count. Results showed that beside cells acclimated at lower ethanol concentration (6% v/v) became more susceptible to drying than nonacclimated ones, after rehydration they maintain their increased ability to grow in a synthetic wine. Acclimation at a higher ethanol concentration (10% v/v) produces several damages on the cell surface losing its ability to grow in a synthetic wine. In this work, we showed for the first time that sublethal alterations on bacterial surface induced by a pre-acclimation with a low ethanol concentration (6%), upon a freeze-drying process, result in a better bacterial adaptation to the stress conditions of wine-like medium, as well as to the preservation process. Understanding the adaptation to ethanol of oenological strains and their effects on the preservation process has a strong impact on winemaking process and allows to define the most appropriate conditions to obtain malolactic starters cultures. © 2015 The Society for Applied Microbiology.

Advancing land surface model development with satellite-based Earth observations

Science.gov (United States)

Orth, Rene; Dutra, Emanuel; Trigo, Isabel F.; Balsamo, Gianpaolo

2017-05-01

The land surface forms an essential part of the climate system. It interacts with the atmosphere through the exchange of water and energy and hence influences weather and climate, as well as their predictability. Correspondingly, the land surface model (LSM) is an essential part of any weather forecasting system. LSMs rely on partly poorly constrained parameters, due to sparse land surface observations. With the use of newly available land surface temperature observations, we show in this study that novel satellite-derived datasets help improve LSM configuration, and hence can contribute to improved weather predictability. We use the Hydrology Tiled ECMWF Scheme of Surface Exchanges over Land (HTESSEL) and validate it comprehensively against an array of Earth observation reference datasets, including the new land surface temperature product. This reveals satisfactory model performance in terms of hydrology but poor performance in terms of land surface temperature. This is due to inconsistencies of process representations in the model as identified from an analysis of perturbed parameter simulations. We show that HTESSEL can be more robustly calibrated with multiple instead of single reference datasets as this mitigates the impact of the structural inconsistencies. Finally, performing coupled global weather forecasts, we find that a more robust calibration of HTESSEL also contributes to improved weather forecast skills. In summary, new satellite-based Earth observations are shown to enhance the multi-dataset calibration of LSMs, thereby improving the representation of insufficiently captured processes, advancing weather predictability, and understanding of climate system feedbacks.

Fatigue damage mechanism and strength of woven laminates

International Nuclear Information System (INIS)

Xiao, J.; Bathias, C.

1993-01-01

The apparent secant stiffness changes with the cyclic number for both unnotched and notched woven laminated specimens (two orthotropic and one quasi-isotropic) during tensile fatigue test at a fixed ratio of maximum fatigue load to UTS were observed. The observable damage initiation and evolution as a function of the cyclic number were directly measured at the notched specimen surface with a video-camera system. The fatigue strengths of the unnotched and notched specimens were determined. The results show that the normalized apparent secant stiffness change curves as a function of cyclic numbers can be divided into three stages. For the first and the second stages in notched specimens and for total life of unnotched specimens, the damage has not been evidently observed and certainly verified with the traditional experimental methods such as radiography and microscopy although many acoustic emission signals can be obtained. The last stage for the notched specimens (N/Nf>0.4, the secant stiffness decreases fast) corresponds to the initiation and evolution of the observable damages. The fatigue strength of these woven composite laminates is dominated by the third stage during which the observable damage develops along the specimen ligament until fracture. During the third stage, a critical dimension at the specimen ligament and a life threshold can be found beyond which a final catastrophic fracture will immediately occur. The quasi-isotropic laminate is of a fatigue strength lower than the two orthotropic laminates of which the fatigue strengths are approaching to each other. The fatigue life is also influenced by the stacking sequences. (orig.)

Gear Fault Detection Effectiveness as Applied to Tooth Surface Pitting Fatigue Damage

Science.gov (United States)

Lewicki, David G.; Dempsey, Paula J.; Heath, Gregory F.; Shanthakumaran, Perumal

2010-01-01

A study was performed to evaluate fault detection effectiveness as applied to gear-tooth-pitting-fatigue damage. Vibration and oil-debris monitoring (ODM) data were gathered from 24 sets of spur pinion and face gears run during a previous endurance evaluation study. Three common condition indicators (RMS, FM4, and NA4 [Ed. 's note: See Appendix A-Definitions D were deduced from the time-averaged vibration data and used with the ODM to evaluate their performance for gear fault detection. The NA4 parameter showed to be a very good condition indicator for the detection of gear tooth surface pitting failures. The FM4 and RMS parameters perfomu:d average to below average in detection of gear tooth surface pitting failures. The ODM sensor was successful in detecting a significant 8lDOunt of debris from all the gear tooth pitting fatigue failures. Excluding outliers, the average cumulative mass at the end of a test was 40 mg.

1.06 μm 150 psec laser damage study of diamond turned, diamond turned/polished and polished metal mirrors

International Nuclear Information System (INIS)

Saito, T.T.; Milam, D.; Baker, P.; Murphy, G.

1975-01-01

Using a well characterized 1.06 μm 150 ps glass laser pulse the damage characteristics for diamond turned, diamond turned/ polished, and polished copper and silver mirrors less than 5 cm diameter were studied. Although most samples were tested with a normal angle of incidence, some were tested at 45 0 with different linear polarization showing an increase in damage threshold for S polarization. Different damage mechanisms observed will be discussed. Laser damage is related to residual surface influences of the fabrication process. First attempts to polish diamond turned surfaces resulted in a significant decrease in laser damage threshold. The importance of including the heat of fusion in the one dimensional heat analysis of the theoretical damage threshold and how close the samples came to the theoretical damage threshold is discussed. (auth)

Recent progress of hydrogen isotope behavior studies for neutron or heavy ion damaged W

International Nuclear Information System (INIS)

Oya, Yasuhisa; Hatano, Yuji; Shimada, Masashi; Buchenauer, Dean; Kolasinski, Robert; Merrill, Brad; Kondo, Sosuke; Hinoki, Tatsuya; Alimov, Vladimir Kh.

2016-01-01

Highlights: • This paper reviews recent results pertaining to hydrogen isotope behavior in neutron and heavy ion damaged W. • Accumulation of damage in W creates stable trapping sites for hydrogen isotopes, thereby changing the observed desorption behavior. • The distribution of defects throughout the sample also changes the shape of TDS spectrum. • Experimental results show that production of Re by nuclear reaction of W with neutrons reduces the density of trapping sites, though no remarkable retention enhancement is observed. - Abstract: This paper reviews recent results pertaining to hydrogen isotope behavior in neutron and heavy ion damaged W. Accumulation of damage in W creates stable trapping sites for hydrogen isotopes, thereby changing the observed desorption behavior. In particular, the desorption temperature shifts higher as the defect concentration increases. In addition, the distribution of defects throughout the sample also changes the shape of TDS spectrum. Even if low energy traps were distributed in the bulk region, the D diffusion toward the surface requires additional time for trapping/detrapping during surface-to-bulk transport, contributing to a shift of desorption peaks toward higher temperatures. It can be said that both of distribution of damage (e.g. hydrogen isotope trapping sites) and their stabilities would have a large impact on desorption. In addition, transmutation effects should be also considered for an actual fusion environment. Experimental results show that production of Re by nuclear reaction of W with neutrons reduces the density of trapping sites, though no remarkable retention enhancement is observed.

Recent progress of hydrogen isotope behavior studies for neutron or heavy ion damaged W

Energy Technology Data Exchange (ETDEWEB)

Oya, Yasuhisa, E-mail: syoya@ipc.shizuoka.ac.jp [Shizuoka University, 836 Ohya, Suruga-ku Shizuoka 422-8529 (Japan); Hatano, Yuji [University of Toyama, 3190 Gofuku, Toyama 939-8555 (Japan); Shimada, Masashi [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Buchenauer, Dean; Kolasinski, Robert [Sandia National Laboratories, Livermore, CA 94551 (United States); Merrill, Brad [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Kondo, Sosuke; Hinoki, Tatsuya [Kyoto University, Gokasho, Uji 611-0011 (Japan); Alimov, Vladimir Kh. [University of Toyama, 3190 Gofuku, Toyama 939-8555 (Japan)

2016-12-15

Highlights: • This paper reviews recent results pertaining to hydrogen isotope behavior in neutron and heavy ion damaged W. • Accumulation of damage in W creates stable trapping sites for hydrogen isotopes, thereby changing the observed desorption behavior. • The distribution of defects throughout the sample also changes the shape of TDS spectrum. • Experimental results show that production of Re by nuclear reaction of W with neutrons reduces the density of trapping sites, though no remarkable retention enhancement is observed. - Abstract: This paper reviews recent results pertaining to hydrogen isotope behavior in neutron and heavy ion damaged W. Accumulation of damage in W creates stable trapping sites for hydrogen isotopes, thereby changing the observed desorption behavior. In particular, the desorption temperature shifts higher as the defect concentration increases. In addition, the distribution of defects throughout the sample also changes the shape of TDS spectrum. Even if low energy traps were distributed in the bulk region, the D diffusion toward the surface requires additional time for trapping/detrapping during surface-to-bulk transport, contributing to a shift of desorption peaks toward higher temperatures. It can be said that both of distribution of damage (e.g. hydrogen isotope trapping sites) and their stabilities would have a large impact on desorption. In addition, transmutation effects should be also considered for an actual fusion environment. Experimental results show that production of Re by nuclear reaction of W with neutrons reduces the density of trapping sites, though no remarkable retention enhancement is observed.

Surface Snow Density of East Antarctica Derived from In-Situ Observations

Science.gov (United States)

Tian, Y.; Zhang, S.; Du, W.; Chen, J.; Xie, H.; Tong, X.; Li, R.

2018-04-01

Models based on physical principles or semi-empirical parameterizations have used to compute the firn density, which is essential for the study of surface processes in the Antarctic ice sheet. However, parameterization of surface snow density is often challenged by the description of detailed local characterization. In this study we propose to generate a surface density map for East Antarctica from all the filed observations that are available. Considering that the observations are non-uniformly distributed around East Antarctica, obtained by different methods, and temporally inhomogeneous, the field observations are used to establish an initial density map with a grid size of 30 × 30 km2 in which the observations are averaged at a temporal scale of five years. We then construct an observation matrix with its columns as the map grids and rows as the temporal scale. If a site has an unknown density value for a period, we will set it to 0 in the matrix. In order to construct the main spatial and temple information of surface snow density matrix we adopt Empirical Orthogonal Function (EOF) method to decompose the observation matrix and only take first several lower-order modes, because these modes already contain most information of the observation matrix. However, there are a lot of zeros in the matrix and we solve it by using matrix completion algorithm, and then we derive the time series of surface snow density at each observation site. Finally, we can obtain the surface snow density by multiplying the modes interpolated by kriging with the corresponding amplitude of the modes. Comparative analysis have done between our surface snow density map and model results. The above details will be introduced in the paper.

Surface damages of polycrystalline W and La2O3-doped W induced by high-flux He plasma irradiation

Science.gov (United States)

Liu, Lu; Li, Shouzhe; Liu, Dongping; Benstetter, Günther; Zhang, Yang; Hong, Yi; Fan, Hongyu; Ni, Weiyuan; Yang, Qi; Wu, Yunfeng; Bi, Zhenhua

2018-04-01

In this study, polycrystalline tungsten (W) and three oxide dispersed strengthened W with 0.1 vol %, 1.0 vol % and 5.0 vol % lanthanum trioxide (La2O3) were irradiated with low-energy (200 eV) and high-flux (5.8 × 1021 or 1.4 × 1022 ions/m2ṡs) He+ ions at elevated temperature. After He+ irradiation at a fluence of 3.0 × 1025/m2, their surface damages were observed by scanning electron microscopy, energy dispersive spectroscopy, scanning electron microscopy-electron backscatter diffraction, and conductive atomic force microscopy. Micron-sized holes were formed on the surface of W alloys after He+ irradiation at 1100 K. Analysis shows that the La2O3 grains doped in W were sputtered preferentially by the high-flux He+ ions when compared with the W grains. For irradiation at 1550 K, W nano-fuzz was formed at the surfaces of both polycrystalline W and La2O3-doped W. The thickness of the fuzz layers formed at the surface of La2O3-doped W is 40% lower than the one of polycrystalline W. The presence of La2O3 could suppress the diffusion and coalescence of He atoms inside W, which plays an important role in the growth of nanostructures fuzz.

Constraining storm-scale forecasts of deep convective initiation with surface weather observations

Science.gov (United States)

Madaus, Luke

Successfully forecasting when and where individual convective storms will form remains an elusive goal for short-term numerical weather prediction. In this dissertation, the convective initiation (CI) challenge is considered as a problem of insufficiently resolved initial conditions and dense surface weather observations are explored as a possible solution. To better quantify convective-scale surface variability in numerical simulations of discrete convective initiation, idealized ensemble simulations of a variety of environments where CI occurs in response to boundary-layer processes are examined. Coherent features 1-2 hours prior to CI are found in all surface fields examined. While some features were broadly expected, such as positive temperature anomalies and convergent winds, negative temperature anomalies due to cloud shadowing are the largest surface anomaly seen prior to CI. Based on these simulations, several hypotheses about the required characteristics of a surface observing network to constrain CI forecasts are developed. Principally, these suggest that observation spacings of less than 4---5 km would be required, based on correlation length scales. Furthermore, it is anticipated that 2-m temperature and 10-m wind observations would likely be more relevant for effectively constraining variability than surface pressure or 2-m moisture observations based on the magnitudes of observed anomalies relative to observation error. These hypotheses are tested with a series of observing system simulation experiments (OSSEs) using a single CI-capable environment. The OSSE results largely confirm the hypotheses, and with 4-km and particularly 1-km surface observation spacing, skillful forecasts of CI are possible, but only within two hours of CI time. Several facets of convective-scale assimilation, including the need for properly-calibrated localization and problems from non-Gaussian ensemble estimates of the cloud field are discussed. Finally, the characteristics

Surface-based reconstruction and diffusion MRI in the assessment of gray and white matter damage in multiple sclerosis

Science.gov (United States)

Caffini, Matteo; Bergsland, Niels; LaganÃ, Marcella; Tavazzi, Eleonora; Tortorella, Paola; Rovaris, Marco; Baselli, Giuseppe

2014-03-01

Despite advances in the application of nonconventional MRI techniques in furthering the understanding of multiple sclerosis pathogenic mechanisms, there are still many unanswered questions, such as the relationship between gray and white matter damage. We applied a combination of advanced surface-based reconstruction and diffusion tensor imaging techniques to address this issue. We found significant relationships between white matter tract integrity indices and corresponding cortical structures. Our results suggest a direct link between damage in white and gray matter and contribute to the notion of gray matter loss relating to clinical disability.

Response of fuzzy tungsten surfaces to pulsed plasma bombardment

International Nuclear Information System (INIS)

Nishijima, D.; Doerner, R.P.; Iwamoto, D.; Kikuchi, Y.; Miyamoto, M.; Nagata, M.; Sakuma, I.; Shoda, K.; Ueda, Y.

2013-01-01

Damage of fuzzy tungsten surfaces due to a transient plasma load is characterized in terms of mass loss, surface morphology, and optical properties. A single D pulsed (∼0.1–0.2 ms) plasma shot with surface absorbed energy density of ∼1.1 MJ m −2 leads to a mass loss of ∼80 μg, which cannot be explained by physical sputtering. Thus, macroscopic erosion processes such as droplets and dust release as well as arcing are thought to be responsible for the mass loss. In fact, scanning electron microscopy observations reveal the melting of the tips of fuzz and arc tracks. The optical reflectivity of the damaged (melted) surface is measured to be higher than that of an undamaged fuzzy surface (below ∼0.01%). Spectroscopic ellipsometry shows that the refractive index, n, and extinction coefficient, k, increase from n ≈ 1 and k ≈ 0 for an undamaged fuzzy surface with an increase in the degree of damage of fuzz

Thermal damage study of beryllium windows used as vacuum barriers in synchrotron radiation beamlines

International Nuclear Information System (INIS)

Holdener, F.R.; Johnson, G.L.; Karpenko, V.P.; Wiggins, R.K.; Cerino, J.A.; Dormiani, M.T.; Youngman, B.P.; Hoyt, E.W.

1987-01-01

An experimental study to investigate thermal-induced damage to SSRL-designed beryllium foil windows was performed at LLNL's Laser Welding Research Facility. The primary goal of this study was to determine the threshold at which thermal-stress-induced damage occurs in these commonly used vacuum barriers. An Nd:Yag pulsed laser with cylindrical optics and a carefully designed test cell provided a test environment that closely resembles the actual beamline conditions at SSRL. Tests performed on two beryllium window geometries, with different vertical aperture dimensions but equal foil thicknesses of 0.254 mm, resulted in two focused total-power thresholds at which incipient damage was determined. For a beam spot size similar to that of the Beamline-X Wiggler Line, onset of surface damage for a 5-mm by 25-mm aperture window was observed at 170 W after 174,000 laser pulses (1.2-ms pulse at 100 pps). A second window with double the vertical aperture dimension (10 mm by 25 mm) was observed to have surface cracking after 180,000 laser pulses with 85 W impinging its front surface. It failed after approximately 1,000,000 pulses. Another window of the same type (10 mm by 25 mm) received 2,160,000 laser pulses at 74.4 W, and subsequent metallographic sectioning revealed no signs of through-thickness damage. Comparison of windows with equal foil thicknesses and aperture dimensions has effectively identified the heat flux limit for incipient failure. The data show that halving the aperture's vertical dimension allows doubling the total incident power for equivalent onsets of thermal-induced damage

Characterization of thermomechanical damage on tungsten surfaces during long-duration plasma transients

Energy Technology Data Exchange (ETDEWEB)

Rivera, David, E-mail: david.rivera.ucla@gmail.com; Crosby, Tamer; Sheng, Andrew; Ghoniem, Nasr M.

2014-12-15

A new experimental facility constructed at UCLA for the simulation of high heat flux effects on plasma-facing materials is described. The High Energy Flux Test Facility (HEFTY) is equipped with a Praxair model SG-100 plasma gun, which is nominally rated at 80 kW of continuous operation, of which approximately 30 kW reaches the target due to thermal losses. The gun is used to impart high intermittent heat flux to metal samples mounted within a cylindrical chamber. The system is capable of delivering an instantaneous heat flux in the range of 30–300 MW/m{sup 2}, depending on sample proximity to the gun. The duration of the plasma heat flux is in the range of 1–1000 s, making it ideal for studies of mild plasma transients of relatively long duration. Tungsten and tungsten-copper alloy metal samples are tested in these transient heat flux conditions, and the surface is characterized for damage evaluation using optical, SEM, XRD, and micro-fabrication techniques. Results from a Finite Element (FE) thermo-elastoplasticity model indicate that during the heat-up phase of a plasma transient pulse, the majority of the sample surface is under compressive stresses leading to plastic deformation of the surface. Upon sample cooling, the recovered elastic strain of cooler parts of the sample exceeds that from parts that deformed plastically, resulting in a tensile surface self-stress (residual surface stress). The intensity of the residual tensile surface stress is experimentally correlated with the onset of complex surface fracture morphology on the tungsten surface, and extending below the surface region. Micro-compression mechanical tests of W micro-pillars show that the material has significant plasticity, failing by a “barreling” mode before plasma exposure, and by normal dislocation slip and localized shear after plasma exposure. Ongoing modeling of the complex thermo-fracture process, coupled with elasto-plasticity is based on a phase field approach for distributed

Effects of prior surface damage on high-temperature oxidation of Fe-, Ni-, and Co-based alloys

Energy Technology Data Exchange (ETDEWEB)

Blau, Peter Julian [ORNL; Lowe, Tracie M [ORNL; Pint, Bruce A [ORNL

2009-01-01

Multi-component metallic alloys have been developed to withstand high-temperature service in corrosive environments. Some of these applications, like exhaust valve seats in internal combustion engines, must also resist sliding, impact, and abrasion. The conjoint effects of temperature, oxidation, and mechanical contact can result in accelerated wear and the formation of complex surface layers whose properties differ from those of the base metal and the oxide scale that forms in the absence of mechanical contact. The authors have investigated the effects of prior surface damage, produced by scratch tests, on the localized reformation of oxide layers. Three high-performance commercial alloys, based on iron, nickel, and cobalt, were used as model materials. Thermogravimetric analysis (TGA) was used to determine their static oxidation rates at elevated temperature (850o C). A micro-abrasion, ball-cratering technique was used to measure oxide layer thickness and to compare it with TGA results. By using taper-sectioning techniques and energy-dispersive elemental mapping, a comparison was made between oxide compositions grown on non-damaged surfaces and oxides that formed on grooves produced by a diamond stylus. Microindentation and scratch hardness data revealed the effects of high temperature exposure on both the substrate hardness and the nature of oxide scale disruption. There were significant differences in elemental distribution between statically-formed oxides and those that formed on scratched regions

Observational study of surface wind along a sloping surface over mountainous terrain during winter

Science.gov (United States)

Lee, Young-Hee; Lee, Gyuwon; Joo, Sangwon; Ahn, Kwang-Deuk

2018-03-01

The 2018 Winter Olympic and Paralympic Games will be held in Pyeongchang, Korea, during February and March. We examined the near surface winds and wind gusts along the sloping surface at two outdoor venues in Pyeongchang during February and March using surface wind data. The outdoor venues are located in a complex, mountainous terrain, and hence the near-surface winds form intricate patterns due to the interplay between large-scale and locally forced winds. During February and March, the dominant wind at the ridge level is westerly; however, a significant wind direction change is observed along the sloping surface at the venues. The winds on the sloping surface are also influenced by thermal forcing, showing increased upslope flow during daytime. When neutral air flows over the hill, the windward and leeward flows show a significantly different behavior. A higher correlation of the wind speed between upper- and lower-level stations is shown in the windward region compared with the leeward region. The strong synoptic wind, small width of the ridge, and steep leeward ridge slope angle provide favorable conditions for flow separation at the leeward foot of the ridge. The gust factor increases with decreasing surface elevation and is larger during daytime than nighttime. A significantly large gust factor is also observed in the leeward region.

Evaluation of surface layer flux parameterizations using in-situ observations

Science.gov (United States)

Katz, Jeremy; Zhu, Ping

2017-09-01

Appropriate calculation of surface turbulent fluxes between the atmosphere and the underlying ocean/land surface is one of the major challenges in geosciences. In practice, the surface turbulent fluxes are estimated from the mean surface meteorological variables based on the bulk transfer model combined with the Monnin-Obukhov Similarity (MOS) theory. Few studies have been done to examine the extent to which such a flux parameterization can be applied to different weather and surface conditions. A novel validation method is developed in this study to evaluate the surface flux parameterization using in-situ observations collected at a station off the coast of Gulf of Mexico. The main findings are: (a) the theoretical prediction that uses MOS theory does not match well with those directly computed from the observations. (b) The largest spread in exchange coefficients is shown in strong stable conditions with calm winds. (c) Large turbulent eddies, which depend strongly on the mean flow pattern and surface conditions, tend to break the constant flux assumption in the surface layer.

Enamel cracks evaluation - A method to predict tooth surface damage during the debonding.

Science.gov (United States)

Dumbryte, Irma; Jonavicius, Tomas; Linkeviciene, Laura; Linkevicius, Tomas; Peciuliene, Vytaute; Malinauskas, Mangirdas

2015-01-01

The objective of this in vitro study was to evaluate the effect of the enamel cracks on the tooth damage during the debonding. Measurements of the cracks characteristics (visibility, direction, length, and location) were performed utilizing a scanning electron microscopy (SEM) technique and mathematically derived formulas (x=h/30, l=n*x) before and following the removal of mechanically retained metal and ceramic brackets. The likelihood of having greater extent enamel defects was higher for the teeth with pronounced cracks (odds vatios, OR=3.728), increased when the crack was located in more than one zone of the tooth (OR=1.998), and the inclination did not exceed 30-45° (OR=0.505). Using ceramic brackets the risk of greater amount tooth structure defects raised 1.45 times (OR=1.450). Enamel crack showing all these characteristics at the beginning of the orthodontic treatment and the use of ceramic brackets might predispose to higher risk of greater extent tooth surface damage after the debonding by 20.4%.

Surface Airways Observations (SAO) Hourly Data 1928-1948 (CDMP)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The dataset consists of hourly U.S. surface airways observations (SAO). These observations extend as far back as 1928, from the time when commercial aviation began...

Titan's Surface Temperatures Maps from Cassini - CIRS Observations

Science.gov (United States)

Cottini, Valeria; Nixon, C. A.; Jennings, D. E.; Anderson, C. M.; Samuelson, R. E.; Irwin, P. G. J.; Flasar, F. M.

2009-09-01

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 μm (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the instrument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature profile by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). In future, application of our methodology over wide areas should greatly increase the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp. 1136-1150, 2008. Rodgers, C. D.: "Inverse Methods For Atmospheric Sounding: Theory and Practice". World Scientific, Singapore, 2000. Jennings, D.E., et al.: "Titan's Surface Brightness Temperatures." Ap. J. L., Vol. 691, pp. L103-L

Improve observation-based ground-level ozone spatial distribution by compositing satellite and surface observations: A simulation experiment

Science.gov (United States)

Zhang, Yuzhong; Wang, Yuhang; Crawford, James; Cheng, Ye; Li, Jianfeng

2018-05-01

Obtaining the full spatial coverage of daily surface ozone fields is challenging because of the sparsity of the surface monitoring network and the difficulty in direct satellite retrievals of surface ozone. We propose an indirect satellite retrieval framework to utilize the information from satellite-measured column densities of tropospheric NO2 and CH2O, which are sensitive to the lower troposphere, to derive surface ozone fields. The method is applicable to upcoming geostationary satellites with high-quality NO2 and CH2O measurements. To prove the concept, we conduct a simulation experiment using a 3-D chemical transport model for July 2011 over the eastern US. The results show that a second order regression using both NO2 and CH2O column densities can be an effective predictor for daily maximum 8-h average ozone. Furthermore, this indirect retrieval approach is shown to be complementary to spatial interpolation of surface observations, especially in regions where the surface sites are sparse. Combining column observations of NO2 and CH2O with surface site measurements leads to an improved representation of surface ozone over simple kriging, increasing the R2 value from 0.53 to 0.64 at a surface site distance of 252 km. The improvements are even more significant with larger surface site distances. The simulation experiment suggests that the indirect satellite retrieval technique can potentially be a useful tool to derive the full spatial coverage of daily surface ozone fields if satellite observation uncertainty is moderate.

Relationship between Deck Level, Body Surface Temperature and Carcass Damages in Italian Heavy Pigs after Short Journeys at Different Unloading Environmental Conditions.

Science.gov (United States)

Arduini, Agnese; Redaelli, Veronica; Luzi, Fabio; Dall'Olio, Stefania; Pace, Vincenzo; Nanni Costa, Leonardo

2017-02-10

In order to evaluate the relationships between deck level, body surface temperature and carcass damages after a short journey (30 min), 10 deliveries of Italian heavy pigs, including a total of 1400 animals from one farm, were examined. Within 5 min after the arrival at the abattoir, the vehicles were unloaded. Environmental temperature and relative humidity were recorded and a Temperature Humidity Index (THI) was calculated. After unloading, maximum temperatures of dorsal and ocular regions were measured by a thermal camera on groups of pigs from each of the unloaded decks. After dehairing, quarters and whole carcasses were evaluated subjectively by a trained operator for skin damage using a four-point scale. On the basis of THI at unloading, deliveries were grouped into three classes. Data of body surface temperature and skin damage score were analysed in a model including THI class, deck level and their interaction. Regardless of pig location in the truck, the maximum temperature of the dorsal and ocular regions increased with increasing THI class. Within each THI class, the highest and lowest body surface temperatures were found in pigs located on the middle and upper decks, respectively. Only THI class was found to affect the skin damage score ( p trucks, even at relatively low temperature and THI, in order to improve welfare and reduce loss of carcass value.

Damage functions for the vulnerability assessment of masonry buildings subjected to tunneling

NARCIS (Netherlands)

Giardina, C.; Hendriks, M.A.N.; Rots, J.G.

2015-01-01

This paper describes a new framework for the assessment of potential damage caused by tunneling-induced settlement to surface masonry buildings. Finite element models in two and three dimensions, validated through comparison with experimental results and field observations, are used to investigate

Surface damage studies of ETFE polymer bombarded with low energy Si ions (≤100 keV)

International Nuclear Information System (INIS)

Minamisawa, Renato Amaral; Almeida, Adelaide De; Budak, Satilmis; Abidzina, Volha; Ila, Daryush

2007-01-01

Surface studies of ethylenetetrafluoroethylene (ETFE), bombarded with Si in a high-energy tandem Pelletron accelerator, have recently been reported. Si ion bombardment with a few MeV to a few hundred keV energies was shown to be sufficient to produce damage on ETFE film. We report here the use of a low energy implanter with Si ion energies lower than 100 keV, to induce changes on ETFE films. In order to determine the radiation damage, ETFE bombarded films were simulated with SRIM software and analyzed with optical absorption photometry (OAP), Raman and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy to show quantitatively the physical and chemical property changes. Carbonization occurs following higher dose implantation, and hydroperoxides were formed following dehydroflorination of the polymer

Low dose radiation damage effects in silicon strip detectors

International Nuclear Information System (INIS)

Wiącek, P.; Dąbrowski, W.

2016-01-01

The radiation damage effects in silicon segmented detectors caused by X-rays have become recently an important research topic driven mainly by development of new detectors for applications at the European X-ray Free Electron Laser (E-XFEL). However, radiation damage in silicon strip is observed not only after extreme doses up to 1 GGy expected at E-XFEL, but also at doses in the range of tens of Gy, to which the detectors in laboratory instruments like X-ray diffractometers or X-ray spectrometers can be exposed. In this paper we report on investigation of radiation damage effects in a custom developed silicon strip detector used in laboratory diffractometers equipped with X-ray tubes. Our results show that significant degradation of detector performance occurs at low doses, well below 200 Gy, which can be reached during normal operation of laboratory instruments. Degradation of the detector energy resolution can be explained by increasing leakage current and increasing interstrip capacitance of the sensor. Another observed effect caused by accumulation of charge trapped in the surface oxide layer is change of charge division between adjacent strips. In addition, we have observed unexpected anomalies in the annealing process.

Low dose radiation damage effects in silicon strip detectors

Science.gov (United States)

Wiącek, P.; Dąbrowski, W.

2016-11-01

The radiation damage effects in silicon segmented detectors caused by X-rays have become recently an important research topic driven mainly by development of new detectors for applications at the European X-ray Free Electron Laser (E-XFEL). However, radiation damage in silicon strip is observed not only after extreme doses up to 1 GGy expected at E-XFEL, but also at doses in the range of tens of Gy, to which the detectors in laboratory instruments like X-ray diffractometers or X-ray spectrometers can be exposed. In this paper we report on investigation of radiation damage effects in a custom developed silicon strip detector used in laboratory diffractometers equipped with X-ray tubes. Our results show that significant degradation of detector performance occurs at low doses, well below 200 Gy, which can be reached during normal operation of laboratory instruments. Degradation of the detector energy resolution can be explained by increasing leakage current and increasing interstrip capacitance of the sensor. Another observed effect caused by accumulation of charge trapped in the surface oxide layer is change of charge division between adjacent strips. In addition, we have observed unexpected anomalies in the annealing process.

Some observations on boiling heat transfer with surface oscillation

International Nuclear Information System (INIS)

Miyashita, H.

1992-01-01

The effects of surface oscillation on pool boiling heat transfer are experimentally studied. Experiments were performed in saturated ethanol and distilled water, covering the range from nucleate to film boiling except in the transition region. Two different geometries were employed as the heating surface with the same wetting area, stainless steel pipe and molybdenum ribbon. The results confirm earlier work on the effect of surface oscillation especially in lower heat flux region of nucleate boiling. Interesting boiling behavior during surface oscillation is observed, which was not referred to in previous work. (2 figures) (Author)

Standard test method for damage to contacting solid surfaces under fretting conditions

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This test method covers the studying or ranking the susceptibility of candidate materials to fretting corrosion or fretting wear for the purposes of material selection for applications where fretting corrosion or fretting wear can limit serviceability. 1.2 This test method uses a tribological bench test apparatus with a mechanism or device that will produce the necessary relative motion between a contacting hemispherical rider and a flat counterface. The rider is pressed against the flat counterface with a loading mass. The test method is intended for use in room temperature air, but future editions could include fretting in the presence of lubricants or other environments. 1.3 The purpose of this test method is to rub two solid surfaces together under controlled fretting conditions and to quantify the damage to both surfaces in units of volume loss for the test method. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5...

Pest damage assessment in fruits and vegetables using thermal imaging

Science.gov (United States)

Vadakkapattu Canthadai, Badrinath; Muthuraju, M. Esakki; Pachava, Vengalrao; Sengupta, Dipankar

2015-05-01

In some fruits and vegetables, it is difficult to visually identify the ones which are pest infested. This particular aspect is important for quarantine and commercial operations. In this article, we propose to present the results of a novel technique using thermal imaging camera to detect the nature and extent of pest damage in fruits and vegetables, besides indicating the level of maturity and often the presence of the pest. Our key idea relies on the fact that there is a difference in the heat capacity of normal and damaged ones and also observed the change in surface temperature over time that is slower in damaged ones. This paper presents the concept of non-destructive evaluation using thermal imaging technique for identifying pest damage levels of fruits and vegetables based on investigations carried out on random samples collected from a local market.

Detecting tangential dislocations on planar faults from traction free surface observations

International Nuclear Information System (INIS)

Ionescu, Ioan R; Volkov, Darko

2009-01-01

We propose in this paper robust reconstruction methods for tangential dislocations on planar faults. We assume that only surface observations are available, and that a traction free condition applies at that surface. This study is an extension to the full three dimensions of Ionescu and Volkov (2006 Inverse Problems 22 2103). We also explore in this present paper the possibility of detecting slow slip events (such as silent earthquakes, or earthquake nucleation phases) from GPS observations. Our study uses extensively an asymptotic estimate for the observed surface displacement. This estimate is first used to derive what we call the moments reconstruction method. Then it is also used for finding necessary conditions for a surface displacement field to have been caused by a slip on a fault. These conditions lead to the introduction of two parameters: the activation factor and the confidence index. They can be computed from the surface observations in a robust fashion. They indicate whether a measured displacement field is due to an active fault. We also infer a second, combined, reconstruction technique blending least square minimization and the moments method. We carefully assess how our reconstruction method is affected by the sensitivity of the observation apparatus and the stepsize for the grid of surface observation points. The maximum permissible stepsize for such a grid is computed for different values of fault depth and orientation. Finally we present numerical examples of reconstruction of faults. We demonstrate that our combined method is sharp, robust and computationally inexpensive. We also note that this method performs satisfactorily for shallow faults, despite the fact that our asymptotic formula deteriorates in that case

Moored surface buoy observations of the diurnal warm layer

KAUST Repository

Prytherch, J.

2013-09-01

An extensive data set is used to examine the dynamics of diurnal warming in the upper ocean. The data set comprises more than 4700 days of measurements at five sites in the tropics and subtropics, obtained from surface moorings equipped to make comprehensive meteorological, incoming solar and infrared radiation, and high-resolution subsurface temperature (and, in some cases, velocity) measurements. The observations, which include surface warmings of up to 3.4°C, are compared with a selection of existing models of the diurnal warm layer (DWL). A simple one-layer physical model is shown to give a reasonable estimate of both the magnitude of diurnal surface warming (model-observation correlation 0.88) and the structure and temporal evolution of the DWL. Novel observations of velocity shear obtained during 346 days at one site, incorporating high-resolution (1 m) upper ocean (5-15 m) acoustic Doppler current profile measurements, are also shown to be in reasonable agreement with estimates from the physical model (daily maximum shear model-observation correlation 0.77). Physics-based improvements to the one-layer model (incorporation of rotation and freshwater terms) are discussed, though they do not provide significant improvements against the observations reported here. The simplicity and limitations of the physical model are used to discuss DWL dynamics. The physical model is shown to give better model performance under the range of forcing conditions experienced across the five sites than the more empirical models. ©2013. American Geophysical Union. All Rights Reserved.

Moored surface buoy observations of the diurnal warm layer

KAUST Repository

Prytherch, J.; Farrar, J. T.; Weller, R. A.

2013-01-01

An extensive data set is used to examine the dynamics of diurnal warming in the upper ocean. The data set comprises more than 4700 days of measurements at five sites in the tropics and subtropics, obtained from surface moorings equipped to make comprehensive meteorological, incoming solar and infrared radiation, and high-resolution subsurface temperature (and, in some cases, velocity) measurements. The observations, which include surface warmings of up to 3.4°C, are compared with a selection of existing models of the diurnal warm layer (DWL). A simple one-layer physical model is shown to give a reasonable estimate of both the magnitude of diurnal surface warming (model-observation correlation 0.88) and the structure and temporal evolution of the DWL. Novel observations of velocity shear obtained during 346 days at one site, incorporating high-resolution (1 m) upper ocean (5-15 m) acoustic Doppler current profile measurements, are also shown to be in reasonable agreement with estimates from the physical model (daily maximum shear model-observation correlation 0.77). Physics-based improvements to the one-layer model (incorporation of rotation and freshwater terms) are discussed, though they do not provide significant improvements against the observations reported here. The simplicity and limitations of the physical model are used to discuss DWL dynamics. The physical model is shown to give better model performance under the range of forcing conditions experienced across the five sites than the more empirical models. ©2013. American Geophysical Union. All Rights Reserved.

Hubble Observes Surface of Titan

Science.gov (United States)

1994-01-01

Scientists for the first time have made images of the surface of Saturn's giant, haze-shrouded moon, Titan. They mapped light and dark features over the surface of the satellite during nearly a complete 16-day rotation. One prominent bright area they discovered is a surface feature 2,500 miles across, about the size of the continent of Australia.Titan, larger than Mercury and slightly smaller than Mars, is the only body in the solar system, other than Earth, that may have oceans and rainfall on its surface, albeit oceans and rain of ethane-methane rather than water. Scientists suspect that Titan's present environment -- although colder than minus 289 degrees Fahrenheit, so cold that water ice would be as hard as granite -- might be similar to that on Earth billions of years ago, before life began pumping oxygen into the atmosphere.Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory and his team took the images with the Hubble Space Telescope during 14 observing runs between Oct. 4 - 18. Smith announced the team's first results last week at the 26th annual meeting of the American Astronomical Society Division for Planetary Sciences in Bethesda, Md. Co-investigators on the team are Mark Lemmon, a doctoral candidate with the UA Lunar and Planetary Laboratory; John Caldwell of York University, Canada; Larry Sromovsky of the University of Wisconsin; and Michael Allison of the Goddard Institute for Space Studies, New York City.Titan's atmosphere, about four times as dense as Earth's atmosphere, is primarily nitrogen laced with such poisonous substances as methane and ethane. This thick, orange, hydrocarbon haze was impenetrable to cameras aboard the Pioneer and Voyager spacecraft that flew by the Saturn system in the late 1970s and early 1980s. The haze is formed as methane in the atmosphere is destroyed by sunlight. The hydrocarbons produced by this methane destruction form a smog similar to that found over large cities, but is much thicker

Evolution of surface topography in dependence on the grain orientation during surface thermal fatigue of polycrystalline copper

CERN Document Server

Aicheler, M; Taborelli, M; Calatroni, S; Neupert, H; Wuensch, W; Sgobba, S

2011-01-01

Surface degradation due to cyclic thermal loading plays a major role in the Accelerating Structures (AS) of the future Compact Linear Collider (CLIC) In this article results on surface degradation of thermally cycled polycrystalline copper as a function of the orientation of surface grains are presented Samples with different grain sizes were subjected to thermal fatigue using two different methods and were then characterized using roughness measurements and Orientation Imaging Scanning-Electron-Microscopy (OIM-SEM) Samples fatigued by a pulsed laser show the same trend in the orientation-fatigue damage accumulation as the sample fatigued by pulsed Radio-Frequency-heating (RF) it is clearly shown that 11 1 1] surface grains develop significantly more damage than the surface grains oriented in {[}100] and three reasons for this behaviour are pointed out Based on observations performed near grain boundaries their role in the crack initiation process is discussed The results are in good agreement with previous f...

Formation of plasma induced surface damage in silica glass etching for optical waveguides

International Nuclear Information System (INIS)

Choi, D.Y.; Lee, J.H.; Kim, D.S.; Jung, S.T.

2004-01-01

Ge, B, P-doped silica glass films are widely used as optical waveguides because of their low losses and inherent compatibility with silica optical fibers. These films were etched by ICP (inductively coupled plasma) with chrome etch masks, which were patterned by reactive ion etching (RIE) using chlorine-based gases. In some cases, the etched surfaces of silica glass were very rough (root-mean square roughness greater than 100 nm) and we call this phenomenon plasma induced surface damage (PISD). Rough surface cannot be used as a platform for hybrid integration because of difficulty in alignment and bonding of active devices. PISD reduces the etch rate of glass and it is very difficult to remove residues on a rough surface. The objective of this study is to elucidate the mechanism of PISD formation. To achieve this goal, PISD formation during different etching conditions of chrome etch mask and silica glass was investigated. In most cases, PISD sources are formed on a glass surface after chrome etching, and metal compounds are identified in theses sources. Water rinse after chrome etching reduces the PISD, due to the water solubility of metal chlorides. PISD is decreased or even disappeared at high power and/or low pressure in glass etching, even if PISD sources were present on the glass surface before etching. In conclusion, PISD sources come from the chrome etching process, and polymer deposition on these sources during the silica etching cause the PISD sources to grow. In the area close to the PISD source there is a higher ion flux, which causes an increase in the etch rate, and results in the formation of a pit

Simultaneous impact of neutron irradiation and sputtering on the surface structure of self–damaged ITER–grade tungsten

Energy Technology Data Exchange (ETDEWEB)

Belyaeva, A. I., E-mail: aibelyaeva@mail.ru; Savchenko, A. A. [National Technical University “Kharkov Politechnical Institute”, Kharkov, 61002 (Ukraine); Galuza, A. A.; Kolenov, I. V. [Institute of Electrophysics and Radiation Technologies, National Academy of Science of Ukraine, Kharkov, 61024 (Ukraine)

2014-07-15

Simultaneous effects of neutron irradiation and long–term sputtering on the surface relief of ITER–grade tungsten were studied. The effects of neutron–induced displacement damage have been simulated by irradiation of tungsten target with W{sup 6+} ions of 20 MeV energy. Ar{sup +} ions with energy 600 eV were used as imitation of charge exchange atoms in ITER. The surface relief was studied after each sputtering act. The singularity in the WJ–IG surface relief was ascertained experimentally at the first time, which determines the law of roughness extension under sputtering. As follows from the experimental data, the neutron irradiation has not to make a decisive additional contribution in the processes developing under impact of charge exchange atoms only.

Interaction of energetic particles with polymer surfaces: surface morphology development and sputtered polymer-fragment ion analysis

International Nuclear Information System (INIS)

Michael, R.S.

1987-01-01

The core of this thesis is based on a series of papers that have been published or will soon be published in which the various processes taking place in the energetic particle-polymer surface interaction scene is investigated. Results presented show different developments on polymer surfaces when compared to the vast experimental data on energetic particle-metal surface interactions. The surface morphology development depends on the physical characteristics of the polymer. Sputtering yields of fluoropolymers were several orders higher than the sputtering yields of aliphatic and aromatic polymers. Depending on the chemical nature of the polymer, the surface morphology development was dependent upon the extent of radiation-damage accumulation. Fast Atom Bombardment Mass Spectrometry at low and high resolution was applied to the characterization of sputtered polymer fragment ions. Fragment ions and their intensities were used to identify polymer samples, observe radiation damage accumulation and probe polymer-polymer interface of a polymer-polymer sandwich structure. A model was proposed which attempts to explain the nature of processes involved in the energetic particle-polymer surface interaction region

How to most effectively expand the global surface ozone observing network

Directory of Open Access Journals (Sweden)

E. D. Sofen

2016-02-01

Full Text Available Surface ozone observations with modern instrumentation have been made around the world for more than 40 years. Some of these observations have been made as one-off activities with short-term, specific science objectives and some have been made as part of wider networks which have provided a foundational infrastructure of data collection, calibration, quality control, and dissemination. These observations provide a fundamental underpinning to our understanding of tropospheric chemistry, air quality policy, atmosphere–biosphere interactions, etc. brought together eight of these networks to provide a single data set of surface ozone observations. We investigate how representative this combined data set is of global surface ozone using the output from a global atmospheric chemistry model. We estimate that on an area basis, 25 % of the globe is observed (34 % land, 21 % ocean. Whereas Europe and North America have almost complete coverage, other continents, Africa, South America, Australia, and Asia (12–17 % show significant gaps. Antarctica is surprisingly well observed (78 %. Little monitoring occurs over the oceans, with the tropical and southern oceans particularly poorly represented. The surface ozone over key biomes such as tropical forests and savanna is almost completely unmonitored. A chemical cluster analysis suggests that a significant number of observations are made of polluted air masses, but cleaner air masses whether over the land or ocean (especially again in the tropics are significantly under-observed. The current network is unlikely to see the impact of the El Niño–Southern Oscillation (ENSO but may be capable of detecting other planetary-scale signals. Model assessment and validation activities are hampered by a lack of observations in regions where the models differ substantially, as is the ability to monitor likely changes in surface ozone over the next century. Using our methodology we are able to suggest new

How to most effectively expand the global surface ozone observing network

Science.gov (United States)

Sofen, E. D.; Bowdalo, D.; Evans, M. J.

2016-02-01

Surface ozone observations with modern instrumentation have been made around the world for more than 40 years. Some of these observations have been made as one-off activities with short-term, specific science objectives and some have been made as part of wider networks which have provided a foundational infrastructure of data collection, calibration, quality control, and dissemination. These observations provide a fundamental underpinning to our understanding of tropospheric chemistry, air quality policy, atmosphere-biosphere interactions, etc. brought together eight of these networks to provide a single data set of surface ozone observations. We investigate how representative this combined data set is of global surface ozone using the output from a global atmospheric chemistry model. We estimate that on an area basis, 25 % of the globe is observed (34 % land, 21 % ocean). Whereas Europe and North America have almost complete coverage, other continents, Africa, South America, Australia, and Asia (12-17 %) show significant gaps. Antarctica is surprisingly well observed (78 %). Little monitoring occurs over the oceans, with the tropical and southern oceans particularly poorly represented. The surface ozone over key biomes such as tropical forests and savanna is almost completely unmonitored. A chemical cluster analysis suggests that a significant number of observations are made of polluted air masses, but cleaner air masses whether over the land or ocean (especially again in the tropics) are significantly under-observed. The current network is unlikely to see the impact of the El Niño-Southern Oscillation (ENSO) but may be capable of detecting other planetary-scale signals. Model assessment and validation activities are hampered by a lack of observations in regions where the models differ substantially, as is the ability to monitor likely changes in surface ozone over the next century. Using our methodology we are able to suggest new sites which would help to close

Relative binding affinity of carboxylate-, phosphonate-, and bisphosphonate-functionalized gold nanoparticles targeted to damaged bone tissue

Energy Technology Data Exchange (ETDEWEB)

Ross, Ryan D. [Rush University Medical Center, Department of Anatomy and Cell Biology (United States); Cole, Lisa E.; Roeder, Ryan K., E-mail: rroeder@nd.edu [University of Notre Dame, Department of Aerospace and Mechanical Engineering Bioengineering Graduate Program (United States)

2012-10-15

Functionalized Au NPs have received considerable recent interest for targeting and labeling cells and tissues. Damaged bone tissue can be targeted by functionalizing Au NPs with molecules exhibiting affinity for calcium. Therefore, the relative binding affinity of Au NPs surface functionalized with either carboxylate (l-glutamic acid), phosphonate (2-aminoethylphosphonic acid), or bisphosphonate (alendronate) was investigated for targeted labeling of damaged bone tissue in vitro. Targeted labeling of damaged bone tissue was qualitatively verified by visual observation and backscattered electron microscopy, and quantitatively measured by the surface density of Au NPs using field-emission scanning electron microscopy. The surface density of functionalized Au NPs was significantly greater within damaged tissue compared to undamaged tissue for each functional group. Bisphosphonate-functionalized Au NPs exhibited a greater surface density labeling damaged tissue compared to glutamic acid- and phosphonic acid-functionalized Au NPs, which was consistent with the results of previous work comparing the binding affinity of the same functionalized Au NPs to synthetic hydroxyapatite crystals. Targeted labeling was enabled not only by the functional groups but also by the colloidal stability in solution. Functionalized Au NPs were stabilized by the presence of the functional groups, and were shown to remain well dispersed in ionic (phosphate buffered saline) and serum (fetal bovine serum) solutions for up to 1 week. Therefore, the results of this study suggest that bisphosphonate-functionalized Au NPs have potential for targeted delivery to damaged bone tissue in vitro and provide motivation for in vivo investigation.

Excavation damage and organic growth in a 1.2m diameter borehole

International Nuclear Information System (INIS)

Everitt, R.A.; Gann, P.; Brown, D.A.; Boychuk, D.M.

1994-01-01

A 1.24m diameter borehole was drilled 5m into the floor of a typical drill-and-blast tunnel in unfractured granite, at AECL's Underground Research Laboratory. Three generations of excavation damage, characteristic of what may be encountered in boreholes excavated for in-hole emplacement of used fuel wastes was observed. These include: (1) damage related to the initial excavation of the room, (2) damage caused by the drilling of the borehole itself, and (3) damage due to subsequent stress-induced spalling of the borehole walls. A biofilm containing a variety of microorganisms has developed where seepage issues from the concrete-granite interface. The biota were introduced from surface water used for mining and drilling. Their growth has been stimulated by residues from blasting and drilling, which have concentrated iron and silicon by passive sorption and energy metabolism. Ferrous iron has been oxidized and precipitated as ferrihydrite/hematite to give an orange/brown colouration on the biofilm interface black. These observations, significant to the understanding and monitoring of excavation damage, highlight the importance of thorough, in situ, multi-disciplinary characterization for vault design

The modal surface interpolation method for damage localization

Science.gov (United States)

Pina Limongelli, Maria

2017-05-01

The Interpolation Method (IM) has been previously proposed and successfully applied for damage localization in plate like structures. The method is based on the detection of localized reductions of smoothness in the Operational Deformed Shapes (ODSs) of the structure. The IM can be applied to any type of structure provided the ODSs are estimated accurately in the original and in the damaged configurations. If the latter circumstance fails to occur, for example when the structure is subjected to an unknown input(s) or if the structural responses are strongly corrupted by noise, both false and missing alarms occur when the IM is applied to localize a concentrated damage. In order to overcome these drawbacks a modification of the method is herein investigated. An ODS is the deformed shape of a structure subjected to a harmonic excitation: at resonances the ODS are dominated by the relevant mode shapes. The effect of noise at resonance is usually lower with respect to other frequency values hence the relevant ODS are estimated with higher reliability. Several methods have been proposed to reliably estimate modal shapes in case of unknown input. These two circumstances can be exploited to improve the reliability of the IM. In order to reduce or eliminate the drawbacks related to the estimation of the ODSs in case of noisy signals, in this paper is investigated a modified version of the method based on a damage feature calculated considering the interpolation error relevant only to the modal shapes and not to all the operational shapes in the significant frequency range. Herein will be reported the comparison between the results of the IM in its actual version (with the interpolation error calculated summing up the contributions of all the operational shapes) and in the new proposed version (with the estimation of the interpolation error limited to the modal shapes).

Damage Localization of Severely Damaged RC-Structures Based on Measured Eigenperiods from a Single Response

DEFF Research Database (Denmark)

Skjærbæk, P. S.; Nielsen, Søren R.K.; Cakmak, A. S.

This paper deals with the estimation of the damage location of severely damaged Reinforced Concrete (RC) structures excited by earthquakes. It is assumed that the building is instrumented with a sensor measuring the earthquake acceleration signal at ground surface and a sensor measuring only...

Temporal observations of surface soil moisture using a passive microwave sensor

International Nuclear Information System (INIS)

Jackson, T.J.; O'Neill, P.

1987-01-01

A series of 10 aircraft flights was conducted over agricultural fields to evaluate relationships between observed surface soil moisture and soil moisture predicted using passive microwave sensor observations. An a priori approach was used to predict values of surface soil moisture for three types of fields: tilled corn, no-till corn with soybean stubble, and idle fields with corn stubble. Acceptable predictions were obtained for the tilled corn fields, while poor results were obtained for the others. The source of error is suspected to be the density and orientation of the surface stubble layer; however, further research is needed to verify this explanation. Temporal comparisons between observed, microwave predicted, and soil water-simulated moisture values showed similar patterns for tilled well-drained fields. Divergences between the observed and simulated measurements were apparent on poorly drained fields. This result may be of value in locating and mapping hydrologic contributing areas

Relationship between Deck Level, Body Surface Temperature and Carcass Damages in Italian Heavy Pigs after Short Journeys at Different Unloading Environmental Conditions

Directory of Open Access Journals (Sweden)

Agnese Arduini

2017-02-01

Full Text Available In order to evaluate the relationships between deck level, body surface temperature and carcass damages after a short journey (30 min, 10 deliveries of Italian heavy pigs, including a total of 1400 animals from one farm, were examined. Within 5 min after the arrival at the abattoir, the vehicles were unloaded. Environmental temperature and relative humidity were recorded and a Temperature Humidity Index (THI was calculated. After unloading, maximum temperatures of dorsal and ocular regions were measured by a thermal camera on groups of pigs from each of the unloaded decks. After dehairing, quarters and whole carcasses were evaluated subjectively by a trained operator for skin damage using a four-point scale. On the basis of THI at unloading, deliveries were grouped into three classes. Data of body surface temperature and skin damage score were analysed in a model including THI class, deck level and their interaction. Regardless of pig location in the truck, the maximum temperature of the dorsal and ocular regions increased with increasing THI class. Within each THI class, the highest and lowest body surface temperatures were found in pigs located on the middle and upper decks, respectively. Only THI class was found to affect the skin damage score (p < 0.05, which increased on quarters and whole carcasses with increasing THI class. The results of this study on short-distance transport of Italian heavy pigs highlighted the need to control and ameliorate the environmental conditions in the trucks, even at relatively low temperature and THI, in order to improve welfare and reduce loss of carcass value.

Evolution of transiently melt damaged tungsten under ITER-relevant divertor plasma heat loading

Energy Technology Data Exchange (ETDEWEB)

Bardin, S., E-mail: s.bardin@differ.nl [FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, Ass EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein (Netherlands); Morgan, T.W. [FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, Ass EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein (Netherlands); Glad, X. [Université de Lorraine, Institut Jean Lamour, Vandoeuvre-les-Nancy (France); Pitts, R.A. [ITER Organization, CS 90 046, 13067 St Paul Lez Durance Cedex (France); De Temmerman, G. [FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, Ass EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein (Netherlands); ITER Organization, CS 90 046, 13067 St Paul Lez Durance Cedex (France)

2015-08-15

A high-repetition-rate ELM simulation system was used at both the Pilot-PSI and Magnum-PSI linear plasma devices to investigate the nature of W damage under multiple shallow melt events and the subsequent surface evolution under ITER relevant plasma fluence and high ELM number. First, repetitive shallow melting of two W monoblocks separated by a 0.5 mm gap was obtained by combined pulsed/steady-state hydrogen plasma loading at normal incidence in the Pilot-PSI device. Surface modifications including melting, cracking and strong net-reshaping of the surface are obtained. During the second step, the pre-damaged W sample was exposed to a high flux plasma regime in the Magnum-PSI device with a grazing angle of 35°. SEM analysis indicates no measurable change to the surface state after the exposure in Magnum-PSI. An increase in transient-induced temperature rise of 40% is however observed, indicating a degradation of thermal properties over time.

Damage symptoms of plants due to PAN exposure

Energy Technology Data Exchange (ETDEWEB)

Nouchi, I; Sawada, T; Ohashi, T; Odaira, T

1974-11-01

In order to identify the cause of plant damage which differed from that by ozone, a series of exposure experiments was carried out on Beta vulgaris, Japanese radish, French bean, luthern, tomato, and spinach in a controlled weather room by artificially synthesized PAN (peroxyacetyl nitrate). The damage appeared generally on younger leaves as a lustering and bronzing on the lower surface; there was a specific symptom in which the interveinary part of the lower surface depressed, leaving the veins in relief. At higher concentrations of PAN, damages appeared on the upper surface of leaves, however, bronzing and lustering were clearer during exposure to lower concentrations of PAN. The position of the leaves and the part of a leaf which was damaged were constant in the petunia, morning glory, and tobacco. There was a hyperbolic relationship between the concentration of PAN and the time period of appearance of the damage as was seen during sulfur dioxide and ozone exposures.

Laser induced damage threshold on metallic surfaces during laser cleaning

CSIR Research Space (South Africa)

Labuschagne, K

2005-07-01

Full Text Available laser paint removal. Laser induced damage on 316L stainless steel was studied, with the target subjected to single and multiple pulse irradiations using a Q-switched Nd:YAG, with fluences between 0.15 and 11.8 J/cm2. Several different damage morphologies...

Radiation damage and redeposited-layer formation on plasma facing materials in the TRIAM-1M

International Nuclear Information System (INIS)

Hirai, Takeshi; Tokunaga, Kazutoshi; Fujiwara, Tadashi; Yoshida, Naoaki; Itoh, Satoshi

1997-01-01

As an aim to obtain some informations of material damage at long time discharge and redeposited-layer formed by scrape off layer (SOL), two collector probe experiments were conducted by using Tokamak of Research Institute for Applied Mechanics (TRIAM-IM). As a result, radiation damage due to charge exchange neutral particles of more than 2 MeV high energy component flying from plasma was observed. And in either experiment, redeposited-layer formation due to deposite of impurity atoms in the plasma could be observed. In the first experiment, a redeposited-layer with fine crystalline particles was observed, which was formed to contain multi-component system of Fe, Cr and Ni and light elements O and C. And, in the second experiment, a redeposited-layer grain-grown in which main component was Mo was observed. Surface modification of plasma facing material such as above-mentioned damage induction, redeposited-layer formation, and so on, was thought to much affect deterioration of materials and recycling of hydrogen. (G.K.)

Development of damage probability matrices based on Greek earthquake damage data

Science.gov (United States)

Eleftheriadou, Anastasia K.; Karabinis, Athanasios I.

2011-03-01

A comprehensive study is presented for empirical seismic vulnerability assessment of typical structural types, representative of the building stock of Southern Europe, based on a large set of damage statistics. The observational database was obtained from post-earthquake surveys carried out in the area struck by the September 7, 1999 Athens earthquake. After analysis of the collected observational data, a unified damage database has been created which comprises 180,945 damaged buildings from/after the near-field area of the earthquake. The damaged buildings are classified in specific structural types, according to the materials, seismic codes and construction techniques in Southern Europe. The seismic demand is described in terms of both the regional macroseismic intensity and the ratio α g/ a o, where α g is the maximum peak ground acceleration (PGA) of the earthquake event and a o is the unique value PGA that characterizes each municipality shown on the Greek hazard map. The relative and cumulative frequencies of the different damage states for each structural type and each intensity level are computed in terms of damage ratio. Damage probability matrices (DPMs) and vulnerability curves are obtained for specific structural types. A comparison analysis is fulfilled between the produced and the existing vulnerability models.

Forecasting Frost Damage: Follow the Water

Science.gov (United States)

Rempel, A. W.

2015-12-01

Frost damage takes place when the pressure exerted against pore walls exceeds the cohesive strength of water-infiltrated rock and causes cracks to extend. Elegant theoretical treatments supported by meticulous field and laboratory observations have combined to unravel the basic mechanical and thermodynamic controls in idealized systems. Frost damage is most vigorous when conditions are cold enough that the net pressure exerted against the pore walls can cause crack extension, yet warm enough to enable the flow that supplies further ice growth in the newly opened space. This insight is applied here to develop practical geomorphic process laws for the effects of frost damage at the larger scales that are relevant for describing the evolution of landscapes. To this end, a direct connection is made between the intensity of frost damage and the porosity increase that results from gradients in water flux under conditions that are cold enough for ice-rock interactions to propagate cracks. This implies that the annual temperature variation at the ground surface can be combined with considerations of heat and mass transport to derive rigorous forecasts of the potential for frost damage that are tied to the increases in water mass that accompany solidification in porous rock. As an example, the image shows the depth-integrated porosity change λ promoted by crack growth at temperatures colder than -ΔTc over an annual cycle for different choices of mean annual temperature MAT and surface amplitude A (assuming a thermal diffusivity of 1 mm2/s and a power-law relationship between permeability and undercooling with exponent α=4, such that a base value of 10-14m2 is reached at a reference undercooling of 0.1 ºC). The abrupt onset in cracking once MAT decreases below a threshold is produced by the requirement that undercooling surpass ΔTc in order to generate sufficient pressures to propagate cracks. The eventual reduction and gradual tail in λ at colder MAT is produced by

Thermography detection on the fatigue damage

Science.gov (United States)

Yang, Bing

It has always been a great temptation in finding new methods to in-situ "watch" the material fatigue-damage processes so that in-time reparations will be possible, and failures or losses can be minimized to the maximum extent. Realizing that temperature patterns may serve as fingerprints for stress-strain behaviors of materials, a state-of-art infrared (IR) thermography camera has been used to "watch" the temperature evolutions of both crystalline and amorphous materials "cycle by cycle" during fatigue experiments in the current research. The two-dimensional (2D) thermography technique records the surface-temperature evolutions of materials. Since all plastic deformations are related to heat dissipations, thermography provides an innovative method to in-situ monitor the heat-evolution processes, including plastic-deformation, mechanical-damage, and phase-transformation characteristics. With the understanding of the temperature evolutions during fatigue, thermography could provide the direct information and evidence of the stress-strain distribution, crack initiation and propagation, shear-band growth, and plastic-zone evolution, which will open up wide applications in studying the structural integrity of engineering components in service. In the current research, theoretical models combining thermodynamics and heat-conduction theory have been developed. Key issues in fatigue, such as in-situ stress-strain states, cyclic softening and hardening observations, and fatigue-life predictions, have been resolved by simply monitoring the specimen-temperature variation during fatigue. Furthermore, in-situ visulizations as well as qualitative and quantitative analyses of fatigue-damage processes, such as Luders-band evolutions, crack propagation, plastic zones, and final fracture, have been performed by thermography. As a method requiring no special sample preparation or surface contact by sensors, thermography provides an innovative and convenient method to in-situ monitor

Study of Surface Wear and Damage Induced by Dry Sliding of Tempered AISI 4140 Steel against Hardened AISI 1055 Steel

Directory of Open Access Journals (Sweden)

A. Elhadi

2016-12-01

Full Text Available In industry, the sliding mechanical systems are subject to friction and wear phenomena. These phenomena can be the origin of a reduction of the efficiency of the mechanical system even to be responsible for its incapacity. Generally, the materials of the parts which are moving relative (tribological couple of these systems are low alloy steels and carbon steels, thanks to their good mechanical and tribological properties. The present work aimed to study, the surface wear and damage induced by dry sliding of hard carbon steel AISI 1055 (disc against tempered low alloy steel AISI 4140 (pin with different hardness and applied loads was investigated. The results revealed that the interaction between the applied load and pin hardness result in complex thermo-mechanical behaviour of the worn surfaces. When a lower hardness pin is used, the main wear mechanisms observed on the discs were abrasion, adhesion, and oxidation. When a higher hardness pin is used, the wear of the discs is governed by delamination, oxidation, and plastic deformation. In particular, third-body wear occurs at high applied load resulting in higher wear rate of high hardness pins compared to low hardness pins.

Surface Soil Moisture Memory Estimated from Models and SMAP Observations

Science.gov (United States)

He, Q.; Mccoll, K. A.; Li, C.; Lu, H.; Akbar, R.; Pan, M.; Entekhabi, D.

2017-12-01

Soil moisture memory(SMM), which is loosely defined as the time taken by soil to forget an anomaly, has been proved to be important in land-atmosphere interaction. There are many metrics to calculate the SMM timescale, for example, the timescale based on the time-series autocorrelation, the timescale ignoring the soil moisture time series and the timescale which only considers soil moisture increment. Recently, a new timescale based on `Water Cycle Fraction' (Kaighin et al., 2017), in which the impact of precipitation on soil moisture memory is considered, has been put up but not been fully evaluated in global. In this study, we compared the surface SMM derived from SMAP observations with that from land surface model simulations (i.e., the SMAP Nature Run (NR) provided by the Goddard Earth Observing System, version 5) (Rolf et al., 2014). Three timescale metrics were used to quantify the surface SMM as: T0 based on the soil moisture time series autocorrelation, deT0 based on the detrending soil moisture time series autocorrelation, and tHalf based on the Water Cycle Fraction. The comparisons indicate that: (1) there are big gaps between the T0 derived from SMAP and that from NR (2) the gaps get small for deT0 case, in which the seasonality of surface soil moisture was removed with a moving average filter; (3) the tHalf estimated from SMAP is much closer to that from NR. The results demonstrate that surface SMM can vary dramatically among different metrics, while the memory derived from land surface model differs from the one from SMAP observation. tHalf, with considering the impact of precipitation, may be a good choice to quantify surface SMM and have high potential in studies related to land atmosphere interactions. References McColl. K.A., S.H. Alemohammad, R. Akbar, A.G. Konings, S. Yueh, D. Entekhabi. The Global Distribution and Dynamics of Surface Soil Moisture, Nature Geoscience, 2017 Reichle. R., L. Qing, D.L. Gabrielle, A. Joe. The "SMAP_Nature_v03" Data

Land surface skin temperature climatology: benefitting from the strengths of satellite observations

International Nuclear Information System (INIS)

Jin Menglin; Dickinson, Robert E

2010-01-01

Surface skin temperature observations (T skin ), as obtained by satellite remote sensing, provide useful climatological information of high spatial resolution and global coverage that enhances the traditional ground observations of surface air temperature (T air ) and so, reveal new information about land surface characteristics. This letter analyzes nine years of moderate-resolution imaging spectroradiometer (MODIS) skin temperature observations to present monthly skin temperature diurnal, seasonal, and inter-annual variations at a 0.05 deg. latitude/longitude grid over the global land surface and combines these measurements with other MODIS-based variables in an effort to understand the physical mechanisms responsible for T skin variations. In particular, skin temperature variations are found to be closely related to vegetation cover, clouds, and water vapor, but to differ from 2 m surface T air in terms of both physical meaning and magnitude. Therefore, the two temperatures (T skin and T air ) are complementary in their contribution of valuable information to the study of climate change.

Study of laser-induced damage on the exit surface of silica components in the nanosecond regime in a multiple wavelengths configuration

International Nuclear Information System (INIS)

Chambonneau, Maxime

2014-01-01

In this thesis, laser-induced damage phenomenon on the surface of fused silica components is investigated in the nanosecond regime. This phenomenon consists in an irreversible modification of the material. In the nanosecond regime, laser damage is tightly correlated to the presence of non-detectable precursor defects which are a consequence of the synthesis and the polishing of the components. In this thesis, we investigate laser damage in a multiple wavelengths configuration. In order to better understand this phenomenon in these conditions of irradiation, three studies are conducted. The first one focuses on damage initiation. The results obtained in the single wavelength configurations highlight a coupling in the multiple wavelengths one. A comparison between the experiments and a model developed during this thesis enables us to improve the knowledge of the fundamental processes involved during this damage phase. Then, we show that post mortem characterizations of damage morphology coupled to an accurate metrology allow us to understand both the nature and also the chronology of the physical mechanisms involved during damage formation. The proposed theoretical scenario is confirmed through various experiments. Finally, we study damage growth in both the single and the multiple wavelengths cases. Once again, this last configuration highlights a coupling between the wavelengths. We show the necessity to account for the spatial characteristics of the laser beams during a growth session. (author) [fr

[Observation of osteoclasts on the root surface during human deciduous teeth resorption].

Science.gov (United States)

Bao, Xiang-jun; Liang, Xing; Chen, Ming; Wang, Hang; Xie, Zhi-gang; Yang, Xiao-yu

2004-08-01

To observe osteoclasts on the resorbing surface of human deciduous teeth. After fixing the collected deciduous teeth, we prepared the tooth slices without decalcification, treated them with HE and TRAP dyestuff, and observed the osteoclasts under light and scanning electron microscope. There were large quantity of various forms of overlapping and huge osteoclasts with many nuclei and silk-like protuberances on the resorbing surface of deciduous teeth. The multinucleated osteoclasts align on the surface of coarse dentin. On the resorbing surface of human deciduous teeth there are large amount of osteoclasts which can be used as a source of studying human osteoclast.

Correlation of damage threshold and surface geometry of nodular defects in HR coatings as determined by in-situ atomic force microscopy

International Nuclear Information System (INIS)

Staggs, M.C.; Kozlowski, M.R.; Siekhaus, W.J.; Balooch, M.

1992-10-01

Atomic force microscopy (AFM) was used to determine in-situ the correlation between the surface dimensions of defects in dielectric multilayer optical coatings and their susceptibility to damage by pulsed laser illumination. The primary surface defects studied were μm-scale domes associated with the classic nodule defect. The optical film studied was a highly reflective dielectric multilayer consisting of pairs of alternating HfO 2 and SiO 2 layers of quarter wave thickness at 1.06 μm. Nodule defect height and width dimensions were measured prior to laser illumination on two different samples. Correlation between these dimensions supported a simple model for the defect geometry. Defects with high nodule heights (> 0.6 μm) were found to be most susceptible to laser damage over a range of fluences between 0-35 J/cm 2 (1.06 μm, 10 ns, and 1/e 2 diam. of 1.3 mm). Crater defects, formed by nodules ejected from the coating prior to illumination, were also studied. None of the crater defects damaged when illuminated over the same range of fluences that the nodule defects were subjected to

Pollution Damage and Protection of Asian Hair

Directory of Open Access Journals (Sweden)

Xin Qu

2018-02-01

Full Text Available Cigarette smoke was used to simulate a polluted environment and an experiment was performed to reveal how virgin and bleached hair are damaged by a polluted environment. The dry/wet combability, surface contact angle, tryptophan content, and cuticle morphology of the smoke exposed hair were evaluated, and compared to unexposed virgin hair. The results showed that pollution exposure can cause significant chemical damage to hair. In particular, virgin hair exposure to pollution can cause damage to the hair cuticles (higher wet/dry combing, protein degradation, and a more hydrophilic hair surface. The experiment also demonstrated that the styling polymer, polyimide-1 (isobutylene/dimethyl amino propyl maleimide/ethoxylated maleimide/maleic acid copolymer, can provide effective protection against such hair damage.

Observation of melt surface depressions during electron beam evaporation

International Nuclear Information System (INIS)

Ohba, Hironori; Shibata, Takemasa

2000-08-01

Depths of depressed surface of liquid gadolinium, cerium and copper during electron beam evaporation were measured by triangulation method using a CCD camera. The depression depths estimated from the balance of the vapor pressure and the hydrostatic pressure at the evaporation surface agreed with the measured values. The periodic fluctuation of atomic beam was observed when the depression of 3∼4 mm in depth was formed at the evaporation spot. (author)

Adatom Fe(III on the hematite surface: Observation of a key reactive surface species

Directory of Open Access Journals (Sweden)

Rosso Kevin M

2004-06-01

Full Text Available The reactivity of a mineral surface is determined by the variety and population of different types of surface sites (e.g., step, kink, adatom, and defect sites. The concept of "adsorbed nutrient" has been built into crystal growth theories, and many other studies of mineral surface reactivity appeal to ill-defined "active sites." Despite their theoretical importance, there has been little direct experimental or analytical investigation of the structure and properties of such species. Here, we use ex-situ and in-situ scanning tunneling microcopy (STM combined with calculated images based on a resonant tunneling model to show that observed nonperiodic protrusions and depressions on the hematite (001 surface can be explained as Fe in an adsorbed or adatom state occupying sites different from those that result from simple termination of the bulk mineral. The number of such sites varies with sample preparation history, consistent with their removal from the surface in low pH solutions.

Determination on Damage Mechanism of the Planet Gear of Heavy Vehicle Final Drive

Science.gov (United States)

Ramdan, RD; Setiawan, R.; Sasmita, F.; Suratman, R.; Taufiqulloh

2018-02-01

The works focus on the investigation of damage mechanism of fractured in the form of spalling of the planet gears from the final drive assembly of 160-ton heavy vehicles. The objective of this work is to clearly understand the mechanism of damage. The work is the first stage of the on-going research on the remaining life estimation of such gears. The understanding of the damage mechanism is critical in order to provide accurate estimate of the gear’s remaining life with observed initial damage. The analysis was performed based on the metallurgy laboratory works, including visual observation, macro-micro fractography by optical stereo and optical microscope and micro-vickers hardness test. From visual observation it was observed pitting that form lining defect at common position, which is at gear flank position. From spalling sample it was observed ratchet mark at the boundary between macro pitting and the edge of fractured parts. Further observation on the cross-section of the samples by optical microscope confirm that initial micro pitting occur without spalling of the case hardened surface. Spalling occur when pitting achieve certain critical size, and occur at multiple initiation site of crack propagation. From the present research it was concluded that pitting was resulted due to repeated contact fatigue. In addition, development of micro to macro pitting as well as spalling occur at certain direction towards the top of the gear teeth.

Photospheric Observations of Surface and Body Modes in Solar Magnetic Pores

Science.gov (United States)

Keys, Peter H.; Morton, Richard J.; Jess, David B.; Verth, Gary; Grant, Samuel D. T.; Mathioudakis, Mihalis; Mackay, Duncan H.; Doyle, John G.; Christian, Damian J.; Keenan, Francis P.; Erdélyi, Robertus

2018-04-01

Over the past number of years, great strides have been made in identifying the various low-order magnetohydrodynamic wave modes observable in a number of magnetic structures found within the solar atmosphere. However, one aspect of these modes that has remained elusive, until now, is their designation as either surface or body modes. This property has significant implications for how these modes transfer energy from the waveguide to the surrounding plasma. Here, for the first time to our knowledge, we present conclusive, direct evidence of these wave characteristics in numerous pores that were observed to support sausage modes. As well as outlining methods to detect these modes in observations, we make estimates of the energies associated with each mode. We find surface modes more frequently in the data, as well as that surface modes appear to carry more energy than those displaying signatures of body modes. We find frequencies in the range of ∼2–12 mHz, with body modes as high as 11 mHz, but we do not find surface modes above 10 mHz. It is expected that the techniques we have applied will help researchers search for surface and body signatures in other modes and in differing structures from those presented here.

Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces

Science.gov (United States)

Carr,; Jeffrey, W [Livermore, CA

2009-03-31

Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

The observed clustering of damaging extratropical cyclones in Europe

Science.gov (United States)

Cusack, Stephen

2016-04-01

The clustering of severe European windstorms on annual timescales has substantial impacts on the (re-)insurance industry. Our knowledge of the risk is limited by large uncertainties in estimates of clustering from typical historical storm data sets covering the past few decades. Eight storm data sets are gathered for analysis in this study in order to reduce these uncertainties. Six of the data sets contain more than 100 years of severe storm information to reduce sampling errors, and observational errors are reduced by the diversity of information sources and analysis methods between storm data sets. All storm severity measures used in this study reflect damage, to suit (re-)insurance applications. The shortest storm data set of 42 years provides indications of stronger clustering with severity, particularly for regions off the main storm track in central Europe and France. However, clustering estimates have very large sampling and observational errors, exemplified by large changes in estimates in central Europe upon removal of one stormy season, 1989/1990. The extended storm records place 1989/1990 into a much longer historical context to produce more robust estimates of clustering. All the extended storm data sets show increased clustering between more severe storms from return periods (RPs) of 0.5 years to the longest measured RPs of about 20 years. Further, they contain signs of stronger clustering off the main storm track, and weaker clustering for smaller-sized areas, though these signals are more uncertain as they are drawn from smaller data samples. These new ultra-long storm data sets provide new information on clustering to improve our management of this risk.

Surface damage on 6H–SiC by highly-charged Xeq+ ions irradiation

International Nuclear Information System (INIS)

Zhang, L.Q.; Zhang, C.H.; Han, L.H.; Xu, C.L.; Li, J.J.; Yang, Y.T.; Song, Y.; Gou, J.; Li, J.Y.; Ma, Y.Z.

2014-01-01

Surface damage on 6H–SiC irradiated by highly-charged Xe q+ (q = 18, 26) ions to different fluences in two geometries was studied by means of AFM, Raman scattering spectroscopy and FTIR spectrometry. The FTIR spectra analysis shows that for Xe 26+ ions irradiation at normal incidence, a deep reflection dip appears at about 930 cm −1 . Moreover, the reflectance on top of reststrahlen band decreases as the ion fluence increases, and the reflectance at tilted incidence is larger than that at normal incidence. The Raman scattering spectra reveal that for Xe 26+ ions at normal incidence, surface reconstruction occurs and amorphous stoichiometric SiC and Si–Si and C–C bonds are generated and original Si–C vibrational mode disappears. And the intensity of scattering peaks decreases with increasing dose. The AFM measurement shows that the surface swells after irradiation. With increasing ion fluence, the step height between the irradiated and the unirradiated region increases for Xe 18+ ions irradiation; while for Xe 26+ ions irradiation, the step height first increases and then decreases with increasing ion fluence. Moreover, the step height at normal incidence is higher than that at tilted incidence by the irradiation with Xe 18+ to the same ion fluence. A good agreement between the results from the three methods is found

Titan's Surface Composition from Cassini VIMS Solar Occultation Observations

Science.gov (United States)

McCord, Thomas; Hayne, Paul; Sotin, Christophe

2013-04-01

Titan's surface is obscured by a thick absorbing and scattering atmosphere, allowing direct observation of the surface within only a few spectral win-dows in the near-infrared, complicating efforts to identify and map geologi-cally important materials using remote sensing IR spectroscopy. We there-fore investigate the atmosphere's infrared transmission with direct measure-ments using Titan's occultation of the Sun as well as Titan's reflectance measured at differing illumination and observation angles observed by Cas-sini's Visual and Infrared Mapping Spectrometer (VIMS). We use two im-portant spectral windows: the 2.7-2.8-mm "double window" and the broad 5-mm window. By estimating atmospheric attenuation within these windows, we seek an empirical correction factor that can be applied to VIMS meas-urements to estimate the true surface reflectance and map inferred composi-tional variations. Applying the empirical corrections, we correct the VIMS data for the viewing geometry-dependent atmospheric effects to derive the 5-µm reflectance and 2.8/2.7-µm reflectance ratio. We then compare the cor-rected reflectances to compounds proposed to exist on Titan's surface. We propose a simple correction to VIMS Titan data to account for atmospheric attenuation and diffuse scattering in the 5-mm and 2.7-2.8 mm windows, generally applicable for airmass water ice for the majority of the low-to-mid latitude area covered by VIMS measurements. Four compositional units are defined and mapped on Titan's surface based on the positions of data clusters in 5-mm vs. 2.8/2.7-mm scatter plots; a simple ternary mixture of H2O, hydrocarbons and CO2 might explain the reflectance properties of these surface units. The vast equatorial "dune seas" are compositionally very homogeneous, perhaps suggesting transport and mixing of particles over very large distances and/or and very consistent formation process and source material. The composi-tional branch characterizing Tui Regio and Hotei Regio is

In-situ observations of the development of heavy-ion damage in semiconductors

International Nuclear Information System (INIS)

Jenkins, M.L.; Chandler, T.J.; Robertson, I.M.; Kirk, M.A.

1985-01-01

In-situ observations on ion-beam induced amorphisation of GaAs, GaP and Si are reported. Direct-impact amorphisation was found to occur in GaAs irradiated with 100-keV Xe + ions to low doses at low temperature (approx. 40K) in contrast to previous room temperature irradiations. In GaP and in silicon, where heavy projectiles do cause direct impact amorphisation at room temperature, the evolution of the damage structure with ion-dose was studied. The defect yield both in GaP irradiated with 100-keV Kr + ions and in Si irradiated with 100-keV Xe + ions was found to decrease monotonically with increasing dose over the dose range 10 15 to 10 17 ions m -2

Surface Airways Observations (SAO) Hourly Data (1965-1981) (CDMP)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The dataset consists primarily of U.S. surface airways observations (SAO) data beginning in 1965 and extending through 1981. Note that a few stations have already...

First results from electron-photon damage equivalence studies on a generic ethylene-propylene rubber

International Nuclear Information System (INIS)

Buckalew, W.H.

1986-04-01

As part of a simulator adequacy assessment program, the relative effectiveness of electrons and photons to produce damage in a generic ethylene propylene rubber (EPR) has been investigated. The investigation was limited in extent in that a single EPR material, in three thickness, was exposed to Cobalt-60 photons and three electron beam energies. Basing material damage on changes in the EPR mechanical properties elongation and tensile strength, we observed that EPR damage was a smoothly varying function of absorbed energy and independent of irradiating particle type. EPR damage tracked equally well as a function of both incident particle energy and material front surface dose. Based on these preliminary data, we tentatively concluded that a correlation between particle, particle energy, and material damage (as measured by changes in material elongation and/or tensile strength) has been demonstrated. 14 figs

Evolution of the microstructure and follow-up of the damage in a duplex steel fatigued in a low number of cycles

International Nuclear Information System (INIS)

Martinelli, Ma C; Alvarez, I; Malarria, J.A

2004-01-01

This work involves carrying out a follow-up of the surface damage to super duplex SAF 2507 stainless steel, cycle deformed with a total deformation range Δε t = 0.8%, until the first fissures appear and correlate with the structure of dislocations. A thin layer preparation technique for transmission electron microscopy was used for this purpose, which preserves one of the faces of the fatigued test piece containing all the surface information. The dislocation structures, crystallographic characteristics and the initiation of fissures in the deformation bands with the surface damage can be studied and correlated. The mechanical tests were carried out for deformation control with a deformation speed of dε/dt = 3 x 10 -3 s -1 . The tests were done for different numbers of cycles and the surface damage was observed under an optic microscope with the contrasting differential interference technique, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The propagation of the slippage lines on the surface could be observed from the austenitic to the ferritic phase, as well as bands of intense deformation and the formation of persistent slippage bands (PSBs), initiation and propagation of fissures relating the structure of dislocations on the surface and just below this in order to connect the location of the plastic deformation and the beginning of the fissure (CW)

7 CFR 51.2294 - Very serious damage.

Science.gov (United States)

2010-01-01

... serious damage. Very serious damage means any defect, other than color, which very seriously affects the... than one-fourth of the surface of the portion of kernel in the aggregate; (c) Discoloration of the meat...

Simulation of Anisotropic Rock Damage for Geologic Fracturing

Science.gov (United States)

Busetti, S.; Xu, H.; Arson, C. F.

2014-12-01

A continuum damage model for differential stress-induced anisotropic crack formation and stiffness degradation is used to study geologic fracturing in rocks. The finite element-based model solves for deformation in the quasi-linear elastic domain and determines the six component damage tensor at each deformation increment. The model permits an isotropic or anisotropic intact or pre-damaged reference state, and the elasticity tensor evolves depending on the stress path. The damage variable, similar to Oda's fabric tensor, grows when the surface energy dissipated by three-dimensional opened cracks exceeds a threshold defined at the appropriate scale of the representative elementary volume (REV). At the laboratory or wellbore scale (1000m) scales the damaged REV reflects early natural fracturing (background or tectonic fracturing) or shear strain localization (fault process zone, fault-tip damage, etc.). The numerical model was recently benchmarked against triaxial stress-strain data from laboratory rock mechanics tests. However, the utility of the model to predict geologic fabric such as natural fracturing in hydrocarbon reservoirs was not fully explored. To test the ability of the model to predict geological fracturing, finite element simulations (Abaqus) of common geologic scenarios with known fracture patterns (borehole pressurization, folding, faulting) are simulated and the modeled damage tensor is compared against physical fracture observations. Simulated damage anisotropy is similar to that derived using fractured rock-mass upscaling techniques for pre-determined fracture patterns. This suggests that if model parameters are constrained with local data (e.g., lab, wellbore, or reservoir domain), forward modeling could be used to predict mechanical fabric at the relevant REV scale. This reference fabric also can be used as the starting material property to pre-condition subsequent deformation or fluid flow. Continuing efforts are to expand the present damage

Damage evaluation system for materials used in fossil thermal power plants

Energy Technology Data Exchange (ETDEWEB)

Okamura, Hiroyuki [Science Univ. of Tokyo (Japan); Sakai, Shinsuke [Tokyo Univ. (Japan); Tomita, Akira [Japan Power Engineering and Inspection Corp., Tokyo (Japan); Koyama, Teruo [Babcock Hitachi K.K., Tokyo (Japan); Sakurai, Shigeo; Kawasaki, Yoshiya [Hitachi Ltd., Ibaraki (Japan)

1998-11-01

The summary of this research paper is as follows: The fundamental design of the damage evaluation system is carried out based on the basic concept. Prototype systems for boilers and turbines have been constructed: (a) Boiler: (I) Evaluation part: Outer surface of the primary pendant superheater tube; (II) Damage mode: Creep; (III) Damage evaluation method: Hardness measurement method; (b) Turbine: (I) Evaluation part: Inner surface at the center bore of high pressure turbine rotor; (II) Damage mode: Creep; (III) Damage evaluation method: Electric potential method. (orig./MM)

Observing at-surface irradiance and albedo from space : The Tibet experiment

NARCIS (Netherlands)

Roupioz, L.

2015-01-01

Monitoring the solar radiation budget on a daily basis is a prerequisite to study land surface processes, especially in climatology and hydrology, and in derived applications like drought early warning. Current space-born radiometers can provide daily observations to derive surface radiative fluxes

Impact of additional surface observation network on short range ...

Indian Academy of Sciences (India)

Stations (AWS) surface observations (temperature and moisture) on the short range forecast over the Indian ... models, which are able to resolve mesoscale fea- ... J. Earth Syst. Sci. ..... terization of the snow field in a cloud model; J. Climate.

Observation of dynamic water microadsorption on Au surface

Energy Technology Data Exchange (ETDEWEB)

Huang, Xiaokang, E-mail: xiaokang.huang@tqs.com; Gupta, Gaurav; Gao, Weixiang; Tran, Van; Nguyen, Bang; McCormick, Eric; Cui, Yongjie; Yang, Yinbao; Hall, Craig; Isom, Harold [TriQuint Semiconductor, Inc., 500 W Renner Road, Richardson, Texas 75080 (United States)

2014-05-15

Experimental and theoretical research on water wettability, adsorption, and condensation on solid surfaces has been ongoing for many decades because of the availability of new materials, new detection and measurement techniques, novel applications, and different scales of dimensions. Au is a metal of special interest because it is chemically inert, has a high surface energy, is highly conductive, and has a relatively high melting point. It has wide applications in semiconductor integrated circuitry, microelectromechanical systems, microfluidics, biochips, jewelry, coinage, and even dental restoration. Therefore, its surface condition, wettability, wear resistance, lubrication, and friction attract a lot of attention from both scientists and engineers. In this paper, the authors experimentally investigated Au{sub 2}O{sub 3} growth, wettability, roughness, and adsorption utilizing atomic force microscopy, scanning electron microscopy, reflectance spectrometry, and contact angle measurement. Samples were made using a GaAs substrate. Utilizing a super-hydrophilic Au surface and the proper surface conditions of the surrounding GaAs, dynamic microadsorption of water on the Au surface was observed in a clean room environment. The Au surface area can be as small as 12 μm{sup 2}. The adsorbed water was collected by the GaAs groove structure and then redistributed around the structure. A model was developed to qualitatively describe the dynamic microadsorption process. The effective adsorption rate was estimated by modeling and experimental data. Devices for moisture collection and a liquid channel can be made by properly arranging the wettabilities or contact angles of different materials. These novel devices will be very useful in microfluid applications or biochips.

Monitoring and modeling of sinkhole-related subsidence in west-central Florida mapped from InSAR and surface observations

Science.gov (United States)

Kiflu, H.; Oliver-Cabrera, T.; Robinson, T.; Wdowinski, S.; Kruse, S.

2017-12-01

Sinkholes in Florida cause millions of dollars in damage to infrastructure each year. Methods of early detection of sinkhole-related subsidence are clearly desirable. We have completed two years of monitoring of selected sinkhole-prone areas in west central Florida with XXX data and analysis with XXX algorithms. Filters for selecting targets with high signal-to-noise ratio and subsidence over this time window (XX-2015-XX-2017) are being used to select sites for ground study. A subset of the buildings with InSAR-detected subsidence indicated show clear structural indications of subsidence in the form of cracks in walls and roofs. Comsol Multiphysics models have been developed to describe subsidence at the rates identified from the InSAR analysis (a few mm/year) and on spatial scales observed from surface observations, including structural deformation of buildings and ground penetrating radar images of subsurface deformation (length scales of meters to tens of meters). These models assume cylindrical symmetry and deformation of elastic and poroelastic layers over a growing sphering void.

Continental-scale water fluxes from continuous GPS observations of Earth surface loading

Science.gov (United States)

Borsa, A. A.; Agnew, D. C.; Cayan, D. R.

2015-12-01

After more than a decade of observing annual oscillations of Earth's surface from seasonal snow and water loading, continuous GPS is now being used to model time-varying terrestrial water fluxes on the local and regional scale. Although the largest signal is typically due to the seasonal hydrological cycle, GPS can also measure subtle surface deformation caused by sustained wet and dry periods, and to estimate the spatial distribution of the underlying terrestrial water storage changes. The next frontier is expanding this analysis to the continental scale and paving the way for incorporating GPS models into the National Climate Assessment and into the observational infrastructure for national water resource management. This will require reconciling GPS observations with predictions from hydrological models and with remote sensing observations from a suite of satellite instruments (e.g. GRACE, SMAP, SWOT). The elastic Earth response which transforms surface loads into vertical and horizontal displacements is also responsible for the contamination of loading observations by tectonic and anthropogenic transients, and we discuss these and other challenges to this new application of GPS.

Observational study of atmospheric surface layer and coastal weather in northern Qatar

Science.gov (United States)

Samanta, Dhrubajyoti; Sadr, Reza

2016-04-01

Atmospheric surface layer is the interaction medium between atmosphere and Earth's surface. Better understanding of its turbulence nature is essential in characterizing the local weather, climate variability and modeling of turbulent exchange processes. The importance of Middle East region, with its unique geographical, economical and weather condition is well recognized. However, high quality micrometeorological observational studies are rare in this region. Here we show experimental results from micrometeorological observations from an experimental site in the coastal region of Qatar during August-December 2015. Measurements of winds are obtained from three sonic anemometers installed on a 9 m tower placed at Al Ghariyah beach in northern Qatar (26.08 °N, 51.36 °E). Different surface layer characteristics is analyzed and compared with earlier studies in equivalent weather conditions. Monthly statistics of wind speed, wind direction, temperature, humidity and heat index are made from concurrent observations from sonic anemometer and weather station to explore variations with surface layer characteristics. The results also highlights potential impact of sea breeze circulation on local weather and atmospheric turbulence. The observed daily maximum temperature and heat index during morning period may be related to sea breeze circulations. Along with the operational micrometeorological observation system, a camera system and ultrasonic wave measurement system are installed recently in the site to study coastline development and nearshore wave dynamics. Overall, the complete observational set up is going to provide new insights about nearshore wind dynamics and wind-wave interaction in Qatar.

LX-10 Explosive Damage Studies

Science.gov (United States)

2015-03-03

opposite end of the vessel. The inside of the bomb is fitted with a stainless steel liner to protect the inner surface and to change the bomb...19  18. Size Fractions for Spherical LX-10 Samples Impact Damaged Between 312 and 416 ft/s...19  19. Spherical LX-10 Sample Impact Damaged at 416 ft/s ....................................... 20  20

Field observations and failure analysis of an excavation damaged zone in the Horonobe Underground Research Laboratory

International Nuclear Information System (INIS)

Aoyagi, Kazuhei; Ishii, Eiichi; Ishida, Tsuyoshi

2017-01-01

In the construction of a deep underground facility, the hydromechanical properties of the rock mass around an underground opening are changed significantly due to stress redistribution. This zone is called an excavation damaged zone (EDZ). In high-level radioactive waste disposal, EDZs can provide a shortcut for the escape of radionuclides to the surface environment. Therefore, it is important to develop a method for predicting the detailed characteristics of EDZs. For prediction of the EDZ in the Horonobe Underground Research Laboratory of Japan, we conducted borehole televiewer surveys, rock core analyses, and repeated hydraulic conductivity measurements. We observed that niche excavation resulted in the formation of extension fractures within 0.2 to 1.0 m into the niche wall, i.e., the extent of the EDZ is within 0.2 to 1.0 m into the niche wall. These results are largely consistent with the results of a finite element analysis implemented with the failure criteria considering failure mode. The hydraulic conductivity in the EDZ was increased by 3 to 5 orders of magnitude compared with the outer zone. The hydraulic conductivity in and around the EDZ has not changed significantly in the two years following excavation of the niche. These results show that short-term unloading due to excavation of the niche created a highly permeable EDZ. (author)

Uncertainty in urban flood damage assessment due to urban drainage modelling and depth-damage curve estimation.

Science.gov (United States)

Freni, G; La Loggia, G; Notaro, V

2010-01-01

Due to the increased occurrence of flooding events in urban areas, many procedures for flood damage quantification have been defined in recent decades. The lack of large databases in most cases is overcome by combining the output of urban drainage models and damage curves linking flooding to expected damage. The application of advanced hydraulic models as diagnostic, design and decision-making support tools has become a standard practice in hydraulic research and application. Flooding damage functions are usually evaluated by a priori estimation of potential damage (based on the value of exposed goods) or by interpolating real damage data (recorded during historical flooding events). Hydraulic models have undergone continuous advancements, pushed forward by increasing computer capacity. The details of the flooding propagation process on the surface and the details of the interconnections between underground and surface drainage systems have been studied extensively in recent years, resulting in progressively more reliable models. The same level of was advancement has not been reached with regard to damage curves, for which improvements are highly connected to data availability; this remains the main bottleneck in the expected flooding damage estimation. Such functions are usually affected by significant uncertainty intrinsically related to the collected data and to the simplified structure of the adopted functional relationships. The present paper aimed to evaluate this uncertainty by comparing the intrinsic uncertainty connected to the construction of the damage-depth function to the hydraulic model uncertainty. In this way, the paper sought to evaluate the role of hydraulic model detail level in the wider context of flood damage estimation. This paper demonstrated that the use of detailed hydraulic models might not be justified because of the higher computational cost and the significant uncertainty in damage estimation curves. This uncertainty occurs mainly

Using quantum dots to tag subsurface damage in lapped and polished glass samples

International Nuclear Information System (INIS)

Williams, Wesley B.; Mullany, Brigid A.; Parker, Wesley C.; Moyer, Patrick J.; Randles, Mark H.

2009-01-01

Grinding, lapping, and polishing are finishing processes used to achieve critical surface parameters in a variety of precision optical and electronic components. As these processes remove material from the surface through mechanical and chemical interactions, they may induce a damaged layer of cracks, voids, and stressed material below the surface. This subsurface damage (SSD) can degrade the performance of a final product by creating optical aberrations due to diffraction, premature failure in oscillating components, and a reduction in the laser induced damage threshold of high energy optics. As these defects lie beneath the surface, they are difficult to detect, and while many methods are available to detect SSD, they can have notable limitations regarding sample size and type, preparation time, or can be destructive in nature. The authors tested a nondestructive method for assessing SSD that consisted of tagging the abrasive slurries used in lapping and polishing with quantum dots (nano-sized fluorescent particles). Subsequent detection of fluorescence on the processed surface is hypothesized to indicate SSD. Quantum dots that were introduced to glass surfaces during the lapping process were retained through subsequent polishing and cleaning processes. The quantum dots were successfully imaged by both wide field and confocal fluorescence microscopy techniques. The detected fluorescence highlighted features that were not observable with optical or interferometric microscopy. Atomic force microscopy and additional confocal microscope analysis indicate that the dots are firmly embedded in the surface but do not appear to travel deep into fractures beneath the surface. Etching of the samples exhibiting fluorescence confirmed that SSD existed. SSD-free samples exposed to quantum dots did not retain the dots in their surfaces, even when polished in the presence of quantum dots.

Viscoplastic behaviour including damage for deep argillaceous rocks: from in situ observations to constitutives equations

International Nuclear Information System (INIS)

Souley, Mountaka; Ghoreychi, Mehdi; Armand, Gilles

2010-01-01

Document available in extended abstract form only. In order to demonstrate the feasibility of a radioactive waste repository in clay-stone formation, French national radioactive waste management agency (ANDRA) started in 2000 to build an underground research laboratory CMHM) at Bure located at nearly 300 km East of Paris. The host formation consists of a clay-stone (Callovo-Oxfordian argillites) and lies between 430 m and 550 m deep. On the basis of numerous campaigns of laboratory tests (uniaxial/triaxial, mono/multi stage creep and relaxation) undertaken for characterizing mechanical and hydro-mechanical short-term or long-term behaviour of these argillites, several constitutive models were developed in the framework of MODEXREP European project and scientific cooperation between ANDRA and national institutions. Moreover, more than 400 m horizontal galleries at the main level of -490 m at CMHM laboratory have been instrumented since April 2005 with the aim to understand the rock behaviour (especially the long term behaviour) needed for the repository design. The continuous measurements of convergencies of the galleries are available contributing to better understand the time-dependent response of the argillites at natural scale. Analysis of convergence data over a period of 2 years leads to the following conclusions: (a) viscoplastic strains are anisotropic and depend on the gallery orientation with regard to the initial stress anisotropy in the investigated formation; (b) the viscoplastic strain rates observed in the undamaged area far from the galleries walls are in the same order of magnitude as those obtained on samples, whereas those recorded in the damaged or fractured zone near to the walls are one to two orders of magnitude higher; indicating the damage and created macroscopic fractures influences on the viscoplastic strains. This influence has not been taken into account in the previous constitutive models. From these observations, a macroscopic

Damage Detection/Locating System Providing Thermal Protection

Science.gov (United States)

Woodard, Stanley E. (Inventor); Jones, Thomas W. (Inventor); Taylor, Bryant D. (Inventor); Qamar, A. Shams (Inventor)

2010-01-01

A damage locating system also provides thermal protection. An array of sensors substantially tiles an area of interest. Each sensor is a reflective-surface conductor having operatively coupled inductance and capacitance. A magnetic field response recorder is provided to interrogate each sensor before and after a damage condition. Changes in response are indicative of damage and a corresponding location thereof.

Silicon surface damage caused by reactive ion etching in fluorocarbon gas mixtures containing hydrogen

International Nuclear Information System (INIS)

Norstroem, H.; Blom, H.; Ostling, M.; Nylandsted Larsen, A.; Keinonen, J.; Berg, S.

1991-01-01

For selective etching of SiO 2 on silicon, gases or gas mixtures containing hydrogen are often used. Hydrogen from the glow discharge promotes the formation of a thin film polymer layer responsible for the selectivity of the etching process. The reactive ion etch (RIE) process is known to create damage in the silicon substrate. The influence of hydrogen on the damage and deactivation of dopants is investigated in the present work. The distribution of hydrogen in silicon, after different etching and annealing conditions have been studied. The influence of the RIE process on the charge carrier concentration in silicon has been investigated. Various analytical techniques like contact resistivity measurements, four point probe measurements, and Hall measurements have been used to determine the influence of the RIE process on the electrical properties of processed silicon wafers. The hydrogen profile in as-etched and post annealed wafers was determined by the 1 H( 15 N,αγ) 12 C nuclear reaction. The depth of the deactivated surface layer is discussed in terms of the impinging hydrogen ion energy, i.e., the possibility of H + ions to pick up an energy equal to the peak-to-peak voltage of the rf signal

Diurnal Variations of Titan's Surface Temperatures From Cassini -CIRS Observations

Science.gov (United States)

Cottini, Valeria; Nixon, Conor; Jennings, Don; Anderson, Carrie; Samuelson, Robert; Irwin, Patrick; Flasar, F. Michael

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 m (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the in-strument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature pro-file by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). The application of our methodology over wide areas has increased the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. In particular we had the chance to look for diurnal variations in surface temperature around the equator: a trend with slowly increasing temperature toward the late afternoon reveals that diurnal temperature changes are present on Titan surface. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp

Validation of the natural resource damage assessment model using historical observations on oil spills

International Nuclear Information System (INIS)

French, D.; Rines, H.

1995-01-01

The Natural Resource Damage Assessment Model for Coastal and Marine Environments (NRDAM/CME) was developed by Applied Science Associates to simulate the fate and effects of oil and chemical spills into estuarine and marine environments. The US Department of the Interior has proposed the NRDAM/CME for use in Natural Resource Damage Assessment (NRDA) regulations under CERCLA. As part of the evaluation of model performance, the NRDAM/CME has been validated with observational data from case histories of oil spills, including the Exxon Valdez, World Prodigy, Mega Borg, Apex Houston and a number of others. Primarily, the data available for validation were of oil slick trajectory and coverage (e.g., overflight maps), length of shoreline oiled, area of marshes oiled, and a number of oiled birds recovered. Model performance was dependent on the accuracy of available wind and current data (the primary forces affecting fate) and bird abundances. Where these data sources were good (relatively well quantified), model performance was excellent. Results of the model simulations also provide an interesting sensitivity analysis and indications of relative effects of oil under various spill scenarios and conditions

The effect of surface corrosion damage on the fatigue life of 6061-T6 aluminum alloy extrusions

Energy Technology Data Exchange (ETDEWEB)

Weber, Matthew; Eason, Paul D.; Özdeş, Hüseyin; Tiryakioğlu, Murat, E-mail: m.tiryakioglu@unf.edu

2017-04-06

An investigation was performed where 6061-T6 extrusions were exposed to a 3.5% NaCl solution at pH 2 for 2 days and 24 days to create distinct surface flaws. The effect of these flaws on the rotating beam fatigue life was then investigated and analyzed by using Wöhler curves, Weibull statistics and scanning electron microscopy (SEM). It was determined that corrosion damage reduced the fatigue life significantly and specimens corroded for both 2-days and 24-days exhibited similar fatigue lives. Statistical analyses showed that fatigue life of all three datasets followed the 3-parameter Weibull distribution and the difference between the fatigue lives of two corroded datasets was statistically insignificant. Analysis of fracture surfaces showed that sizes of pits that led to fatigue crack initiation were very different in the two corroded datasets. Implications of the similarity in fatigue lives despite disparity in surface condition are discussed in detail in the paper.

Detecting surface runoff location in a small catchment using distributed and simple observation method

Science.gov (United States)

Dehotin, Judicaël; Breil, Pascal; Braud, Isabelle; de Lavenne, Alban; Lagouy, Mickaël; Sarrazin, Benoît

2015-06-01

Surface runoff is one of the hydrological processes involved in floods, pollution transfer, soil erosion and mudslide. Many models allow the simulation and the mapping of surface runoff and erosion hazards. Field observations of this hydrological process are not common although they are crucial to evaluate surface runoff models and to investigate or assess different kinds of hazards linked to this process. In this study, a simple field monitoring network is implemented to assess the relevance of a surface runoff susceptibility mapping method. The network is based on spatially distributed observations (nine different locations in the catchment) of soil water content and rainfall events. These data are analyzed to determine if surface runoff occurs. Two surface runoff mechanisms are considered: surface runoff by saturation of the soil surface horizon and surface runoff by infiltration excess (also called hortonian runoff). The monitoring strategy includes continuous records of soil surface water content and rainfall with a 5 min time step. Soil infiltration capacity time series are calculated using field soil water content and in situ measurements of soil hydraulic conductivity. Comparison of soil infiltration capacity and rainfall intensity time series allows detecting the occurrence of surface runoff by infiltration-excess. Comparison of surface soil water content with saturated water content values allows detecting the occurrence of surface runoff by saturation of the soil surface horizon. Automatic records were complemented with direct field observations of surface runoff in the experimental catchment after each significant rainfall event. The presented observation method allows the identification of fast and short-lived surface runoff processes at a small spatial and temporal resolution in natural conditions. The results also highlight the relationship between surface runoff and factors usually integrated in surface runoff mapping such as topography, rainfall

Thermal coupling and damage mechanisms of laser radiation on selected materials

International Nuclear Information System (INIS)

Schwirzke, F.; Jenkins, W.F.; Schmidt, W.R.

1983-01-01

High power laser beams interact with targets by a variety of thermal, impulse, and electrical effects. Energy coupling is considerably enhanced once surface electrical breakdown occurs. The laser heated plasma then causes surface damage via thermal evaporation, ion sputtering, and unipolar arcing. While the first two are purely thermal and mechanical effects, the last one, unipolar arcing, is an electrical plasma-surface interaction process which leads to crater formation, usually called laser-pitting, a process which was often observed but not well understood. Unipolar arcing occurs when a plasma of sufficiently high electron temperature interacts with a surface. Without an external voltage applied, many electrical micro-arcs burn between the surface and the plasma, driven by local variations of the sheath potential with the surface acting as both the cathode and anode. Laser induced unipolar arcing represents the most damaging and non-uniform plasma-surface interaction process since the energy available in the plasma concentrates towards the cathode spots. This causes cratering of the materials surface. The ejection of material in the form of small jets from the craters leads to ripples in the critical plasma density contour. This in turn contributes to the onset of plasma instabilities, small scale magnetic field generation and laser beam filamentation. The ejection of a plasma jet from the unipolar arc crater also causes highly localized shock waves to propagate into the target, softening it in the process. Thus, local surface erosion by unipolar arcing is much more severe than for uniform energy deposition

A New Quantitative Method for the Non-Invasive Documentation of Morphological Damage in Paintings Using RTI Surface Normals

Directory of Open Access Journals (Sweden)

Marcello Manfredi

2014-07-01

Full Text Available In this paper we propose a reliable surface imaging method for the non-invasive detection of morphological changes in paintings. Usually, the evaluation and quantification of changes and defects results mostly from an optical and subjective assessment, through the comparison of the previous and subsequent state of conservation and by means of condition reports. Using quantitative Reflectance Transformation Imaging (RTI we obtain detailed information on the geometry and morphology of the painting surface with a fast, precise and non-invasive method. Accurate and quantitative measurements of deterioration were acquired after the painting experienced artificial damage. Morphological changes were documented using normal vector images while the intensity map succeeded in highlighting, quantifying and describing the physical changes. We estimate that the technique can detect a morphological damage slightly smaller than 0.3 mm, which would be difficult to detect with the eye, considering the painting size. This non-invasive tool could be very useful, for example, to examine paintings and artwork before they travel on loan or during a restoration. The method lends itself to automated analysis of large images and datasets. Quantitative RTI thus eases the transition of extending human vision into the realm of measuring change over time.

History of surface weather observations in the United States

Science.gov (United States)

Fiebrich, Christopher A.

2009-04-01

In this paper, the history of surface weather observations in the United States is reviewed. Local weather observations were first documented in the 17th Century along the East Coast. For many years, the progression of a weather observation from an initial reading to dissemination remained a slow and laborious process. The number of observers remained small and unorganized until agencies including the Surgeon General, Army, and General Land Office began to request regular observations at satellite locations in the 1800s. The Smithsonian was responsible for first organizing a large "network" of volunteer weather observers across the nation. These observers became the foundation for today's Cooperative Observer network. As applications of weather data continued to grow and users required the data with an ever-decreasing latency, automated weather networks saw rapid growth in the later part of the 20th century. Today, the number of weather observations across the U.S. totals in the tens of thousands due largely to privately-owned weather networks and amateur weather observers who submit observations over the internet.

Integrating Satellite, Radar and Surface Observation with Time and Space Matching

Science.gov (United States)

Ho, Y.; Weber, J.

2015-12-01

The Integrated Data Viewer (IDV) from Unidata is a Java™-based software framework for analyzing and visualizing geoscience data. It brings together the ability to display and work with satellite imagery, gridded data, surface observations, balloon soundings, NWS WSR-88D Level II and Level III RADAR data, and NOAA National Profiler Network data, all within a unified interface. Applying time and space matching on the satellite, radar and surface observation datasets will automatically synchronize the display from different data sources and spatially subset to match the display area in the view window. These features allow the IDV users to effectively integrate these observations and provide 3 dimensional views of the weather system to better understand the underlying dynamics and physics of weather phenomena.

Laser-induced damage in optical materials

CERN Document Server

Ristau, Detlev

2014-01-01

Dedicated to users and developers of high-powered systems, Laser-Induced Damage in Optical Materials focuses on the research field of laser-induced damage and explores the significant and steady growth of applications for high-power lasers in the academic, industrial, and military arenas. Written by renowned experts in the field, this book concentrates on the major topics of laser-induced damage in optical materials and most specifically addresses research in laser damage that occurs in the bulk and on the surface or the coating of optical components. It considers key issues in the field of hi

Reconstructing patterns of temperature, phenology, and frost damage over 124 years: spring damage risk is increasing.

Science.gov (United States)

Augspurger, Carol K

2013-01-01

Climate change, with both warmer spring temperatures and greater temperature fluctuations, has altered phenologies, possibly leading to greater risk of spring frost damage to temperate deciduous woody plants. Phenological observations of 20 woody species from 1993 to 2012 in Trelease Woods, Champaign County, Illinois, USA, were used to identify years with frost damage to vegetative and reproductive phases. Local temperature records were used in combination with the phenological observations to determine what combinations of the two were associated with damage. Finally, a long-term temperature record (1889-1992) was evaluated to determine if the frequency of frost damage has risen in recent decades. Frost Frost damage occurred in five years in the interior and in three additional years at only the forest edge. The degree of damage varied with species, life stage, tissue (vegetative or reproductive), and phenological phase. Common features associated with the occurrence of damage to interior plants were (1) a period of unusual warm temperatures in March, followed by (2) a frost event in April with a minimum temperature frost damage increased significantly, from 0.03 during 1889-1979 to 0.21 during 1980-2012. When the criteria were "softened" to frost damage events more common.

Direct Observation of Domain-Wall Surface Tension by Deflating or Inflating a Magnetic Bubble

Science.gov (United States)

Zhang, Xueying; Vernier, Nicolas; Zhao, Weisheng; Yu, Haiming; Vila, Laurent; Zhang, Yue; Ravelosona, Dafiné

2018-02-01

The surface energy of a magnetic domain wall (DW) strongly affects its static and dynamic behaviors. However, this effect is seldom directly observed, and some of the related phenomena are not well understood. Moreover, a reliable method to quantify the DW surface energy is still absent. Here, we report a series of experiments in which the DW surface energy becomes a dominant parameter. We observe that a semicircular magnetic domain bubble can spontaneously collapse under the Laplace pressure induced by DW surface energy. We further demonstrate that the surface energy can lead to a geometrically induced pinning when the DW propagates in a Hall cross or from a nanowire into a nucleation pad. Based on these observations, we develop two methods to quantify the DW surface energy, which can be very helpful in the estimation of intrinsic parameters such as Dzyaloshinskii-Moriya interactions or exchange stiffness in magnetic ultrathin films.

Surface modification of amorphous nanosilica particles suppresses nanosilica-induced cytotoxicity, ROS generation, and DNA damage in various mammalian cells

International Nuclear Information System (INIS)

Yoshida, Tokuyuki; Yoshioka, Yasuo; Matsuyama, Keigo; Nakazato, Yasutaro; Tochigi, Saeko; Hirai, Toshiro; Kondoh, Sayuri; Nagano, Kazuya; Abe, Yasuhiro; Kamada, Haruhiko; Tsunoda, Shin-ichi; Nabeshi, Hiromi; Yoshikawa, Tomoaki; Tsutsumi, Yasuo

2012-01-01

Highlights: ► There is increasing concern regarding the potential health risks of nanomaterials. ► We evaluated the effect of surface properties of nanomaterials on cellular responses. ► We showed that the surface properties play an important in determining its safety. ► These data provide useful information for producing safer nanomaterials. -- Abstract: Recently, nanomaterials have been utilized in various fields. In particular, amorphous nanosilica particles are increasingly being used in a range of applications, including cosmetics, food technology, and medical diagnostics. However, there is concern that the unique characteristics of nanomaterials might induce undesirable effects. The roles played by the physical characteristics of nanomaterials in cellular responses have not yet been elucidated precisely. Here, by using nanosilica particles (nSPs) with a diameter of 70 nm whose surface was either unmodified (nSP70) or modified with amine (nSP70-N) or carboxyl groups (nSP70-C), we examined the relationship between the surface properties of nSPs and cellular responses such as cytotoxicity, reactive oxygen species (ROS) generation, and DNA damage. To compare the cytotoxicity of nSP70, nSP70-N, or nSP70-C, we examined in vitro cell viability after nSP treatment. Although the susceptibility of each cell line to the nSPs was different, nSP70-C and nSP70-N showed lower cytotoxicity than nSP70 in all cell lines. Furthermore, the generation of ROS and induction of DNA damage in nSP70-C- and nSP70-N-treated cells were lower than those in nSP70-treated cells. These results suggest that the surface properties of nSP70 play an important role in determining its safety, and surface modification of nSP70 with amine or carboxyl groups may be useful for the development of safer nSPs. We hope that our results will contribute to the development of safer nanomaterials.

Controls on surface soil drying rates observed by SMAP and simulated by the Noah land surface model

Science.gov (United States)

Shellito, Peter J.; Small, Eric E.; Livneh, Ben

2018-03-01

Drydown periods that follow precipitation events provide an opportunity to assess controls on soil evaporation on a continental scale. We use SMAP (Soil Moisture Active Passive) observations and Noah simulations from drydown periods to quantify the role of soil moisture, potential evaporation, vegetation cover, and soil texture on soil drying rates. Rates are determined using finite differences over intervals of 1 to 3 days. In the Noah model, the drying rates are a good approximation of direct soil evaporation rates, and our work suggests that SMAP-observed drying is also predominantly affected by direct soil evaporation. Data cover the domain of the North American Land Data Assimilation System Phase 2 and span the first 1.8 years of SMAP's operation. Drying of surface soil moisture observed by SMAP is faster than that simulated by Noah. SMAP drying is fastest when surface soil moisture levels are high, potential evaporation is high, and when vegetation cover is low. Soil texture plays a minor role in SMAP drying rates. Noah simulations show similar responses to soil moisture and potential evaporation, but vegetation has a minimal effect and soil texture has a much larger effect compared to SMAP. When drying rates are normalized by potential evaporation, SMAP observations and Noah simulations both show that increases in vegetation cover lead to decreases in evaporative efficiency from the surface soil. However, the magnitude of this effect simulated by Noah is much weaker than that determined from SMAP observations.

3D in situ observations of glass fibre/matrix interfacial debonding

DEFF Research Database (Denmark)

Martyniuk, Karolina; Sørensen, Bent F.; Modregger, Peter

2013-01-01

X-ray microtomography was used for 3D in situ observations of the evolution of fibre/matrix interfacial debonding. A specimen with a single fibre oriented perpendicular to the tensile direction was tested at a synchrotron facility using a special loading rig which allowed for applying a load...... transverse to the fibre. Three distinguishable damage stages were observed: (i) interfacial debond initiation at the free surface, (ii) debond propagation from the surface into the specimen and (iii) unstable debonding along the full length of the scanned volume. The high resolution microtomography provides...

7 CFR 51.1323 - Serious damage.

Science.gov (United States)

2010-01-01

... frost injury, 15 percent of the surface. (3) On Anjou, smooth solid or smooth netlike russeting when the... Standards for Winter Pears 1 Definitions § 51.1323 Serious damage. Serious damage means any injury or defect...) Drought spot when more than two in number, or where the external injury affects an aggregate area of more...

Observation of weak superconductivity in electrons localized on a film surface

International Nuclear Information System (INIS)

Fogel', N.Y.; Kolin'ko, A.E.

1984-01-01

We have observed anomalous abrupt resistance changes in thick vanadium films [d>>xi(T)]. We have also observed a number of anomalies in the H--T phase diagrams for these films; these anomalies are most clearly seen when the field is parallel to, or at low angles of incidence with respect to, the film surface. We explain our results by assuming that there are two different electron systems present in the film. One of them is composed of electrons localized near a natural planar defect, the film surface. This subsystem is characterized by extremely small values of the critical current

Abbreviated machining schedule for fabricating beryllium parts free of surface damage

International Nuclear Information System (INIS)

Beitscher, S.; Capes, J.F.; Leslie, W.W.; Luckow, J.R.; Riegel, R.L.

1979-01-01

This study was performed to develop a more economical method of machining damage-free beryllium components at Rocky Flats. The present method involves a 9-pass schedule of lathe turning followed by a chemical etch. Prototype beryllium hemispherical shell parts and cylindrical tensile specimens machined to simulate the parts were utilized in this study. The main investigative methods used to evaluate the amount of machining damage were metallography and tensile tests. It was found that damage-free parts could be produced by carefully controlled machining if the number of machining passes was reduced to 4 or even 3, if followed by the standard etching treatment. These findings were made on Select S-65 grade beryllium, and probably apply to other common grades of powder source beryllium but not necessarily to ingot-source beryllium. It is recommended that the 4-pass schedule becomes the standard method to produce damage-free beryllium derived from powder. Significant savings in time, labor, and equipment can be realized by this change in method without decreasing the quality of the product

Dissemination of Earth Remote Sensing Data for Use in the NOAA/NWS Damage Assessment Toolkit

Science.gov (United States)

Molthan, Andrew; Burks, Jason; Camp, Parks; McGrath, Kevin; Bell, Jordan

2015-01-01

The National Weather Service has developed the Damage Assessment Toolkit (DAT), an application for smartphones and tablets that allows for the collection, geolocation, and aggregation of various damage indicators that are collected during storm surveys. The DAT supports the often labor-intensive process where meteorologists venture into the storm-affected area, allowing them to acquire geotagged photos of the observed damage while also assigning estimated EF-scale categories based upon their observations. Once the data are collected, the DAT infrastructure aggregates the observations into a server that allows other meteorologists to perform quality control and other analysis steps before completing their survey and making the resulting data available to the public. In addition to in-person observations, Earth remote sensing from operational, polar-orbiting satellites can support the damage assessment process by identifying portions of damage tracks that may be missed due to road limitations, access to private property, or time constraints. Products resulting from change detection techniques can identify damage to vegetation and the land surface, aiding in the survey process. In addition, higher resolution commercial imagery can corroborate ground-based surveys by examining higher-resolution commercial imagery. As part of an ongoing collaboration, NASA and NOAA are working to integrate near real-time Earth remote sensing observations into the NOAA/NWS Damage Assessment Toolkit. This presentation will highlight recent developments in a streamlined approach for disseminating Earth remote sensing data via web mapping services and a new menu interface that has been integrated within the DAT. A review of current and future products will be provided, including products derived from MODIS and VIIRS for preliminary track identification, along with conduits for higher-resolution Landsat, ASTER, and commercial imagery as they become available. In addition to tornado damage

Diclofenac protects cultured human corneal epithelial cells against hyperosmolarity and ameliorates corneal surface damage in a rat model of dry eye.

Science.gov (United States)

Sawazaki, Ryoichi; Ishihara, Tomoaki; Usui, Shinya; Hayashi, Erika; Tahara, Kayoko; Hoshino, Tatsuya; Higuchi, Akihiro; Nakamura, Shigeru; Tsubota, Kazuo; Mizushima, Tohru

2014-04-21

Dry eye syndrome (DES) is characterized by an increase in tear osmolarity and induction of the expression and nuclear localization of an osmoprotective transcription factor (nuclear factor of activated T-cells 5 [NFAT5]) that plays an important role in providing protection against hyperosmotic tears. In this study, we screened medicines already in clinical use with a view of finding compounds that protect cultured human corneal epithelial cells against hyperosmolarity-induced cell damage. Viable cell number was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method and cellular NFAT5 level was measured by immunoblotting. The rat model for DES was developed by removal of the lacrimal glands, with an assessment of corneal surface damage based on levels of fluorescein staining and epithelial apoptosis. Some nonsteroidal anti-inflammatory drugs (NSAIDs), including diclofenac sodium (diclofenac), were identified during the screening procedure. These NSAIDs were able to suppress hyperosmolarity-induced apoptosis and cell growth arrest. In contrast, other NSAIDs, including bromfenac sodium (bromfenac), did not exert such a protective action. Treatment of cells with diclofenac, but not bromfenac, stimulated both the nuclear localization and expression of NFAT5 under hyperosmotic conditions. In the rat model for DES, topical administration of diclofenac (but not bromfenac) to eyes reduced corneal surface damage without affecting the volume of tear fluid. Diclofenac appears to protect cells against hyperosmolarity-induced cell damage and NFAT5 would play an important role in this protective action. The findings reported here may also indicate that the topical administration of diclofenac to eyes may be therapeutically beneficial for DES patients.

Electron backscatter diffraction characterization of laser-induced periodic surface structures on nickel surface

Energy Technology Data Exchange (ETDEWEB)

Sedao, Xxx, E-mail: sedao.xxx@gmail.com [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France); Maurice, Claire [Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines, 42023 St-Etienne (France); Garrelie, Florence; Colombier, Jean-Philippe; Reynaud, Stéphanie [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France); Quey, Romain; Blanc, Gilles [Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines, 42023 St-Etienne (France); Pigeon, Florent [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France)

2014-05-01

Graphical abstract: -- Highlight: •Lattice rotation and its distribution in laser-induced periodic surface structures (LIPSS) and the subsurface region on a nickel substrate are revealed using electron backscatter diffraction (EBSD). -- Abstract: We report on the structural investigation of laser-induced periodic surface structures (LIPSS) generated in polycrystalline nickel target after multi-shot irradiation by femtosecond laser pulses. Electron backscatter diffraction (EBSD) is used to reveal lattice rotation caused by dislocation storage during LIPSS formation. Localized crystallographic damages in the LIPSS are detected from both surface and cross-sectional EBSD studies. A surface region (up to 200 nm) with 1–3° grain disorientation is observed in localized areas from the cross-section of the LIPSS. The distribution of the local disorientation is inhomogeneous across the LIPSS and the subsurface region.

Evaluating Surface Radiation Fluxes Observed From Satellites in the Southeastern Pacific Ocean

Science.gov (United States)

Pinker, R. T.; Zhang, B.; Weller, R. A.; Chen, W.

2018-03-01

This study is focused on evaluation of current satellite and reanalysis estimates of surface radiative fluxes in a climatically important region. It uses unique observations from the STRATUS Ocean Reference Station buoy in a region of persistent marine stratus clouds 1,500 km off northern Chile during 2000-2012. The study shows that current satellite estimates are in better agreement with buoy observations than model outputs at a daily time scale and that satellite data depict well the observed annual cycle in both shortwave and longwave surface radiative fluxes. Also, buoy and satellite estimates do not show any significant trend over the period of overlap or any interannual variability. This verifies the stability and reliability of the satellite data and should make them useful to examine El Niño-Southern Oscillation variability influences on surface radiative fluxes at the STRATUS site for longer periods for which satellite record is available.

Damage pattern and damage progression on breakwater roundheads under multidirectional waves

DEFF Research Database (Denmark)

Comola, F.; Andersen, Thomas Lykke; Martinelli, L.

2014-01-01

An experimental model test study is carried out to investigate damage pattern and progression on a rock armoured breakwater roundhead subjected to multidirectional waves. Concerning damage pattern, the most critical sector is observed to shift leeward with increasing wave period. Taking angles...... over the roundhead is developed. Thus the formula also considers the shifting of the critical sector due to increasing wave period which existing formulae do not include. Finally, analysing the damage produced by double peaked spectra, it is shown that the armour may be designed by the formula when...

Global observation-based diagnosis of soil moisture control on land surface flux partition

Science.gov (United States)

Gallego-Elvira, Belen; Taylor, Christopher M.; Harris, Phil P.; Ghent, Darren; Veal, Karen L.; Folwell, Sonja S.

2016-04-01

Soil moisture plays a central role in the partition of available energy at the land surface between sensible and latent heat flux to the atmosphere. As soils dry out, evapotranspiration becomes water-limited ("stressed"), and both land surface temperature (LST) and sensible heat flux rise as a result. This change in surface behaviour during dry spells directly affects critical processes in both the land and the atmosphere. Soil water deficits are often a precursor in heat waves, and they control where feedbacks on precipitation become significant. State-of-the-art global climate model (GCM) simulations for the Coupled Model Intercomparison Project Phase 5 (CMIP5) disagree on where and how strongly the surface energy budget is limited by soil moisture. Evaluation of GCM simulations at global scale is still a major challenge owing to the scarcity and uncertainty of observational datasets of land surface fluxes and soil moisture at the appropriate scale. Earth observation offers the potential to test how well GCM land schemes simulate hydrological controls on surface fluxes. In particular, satellite observations of LST provide indirect information about the surface energy partition at 1km resolution globally. Here, we present a potentially powerful methodology to evaluate soil moisture stress on surface fluxes within GCMs. Our diagnostic, Relative Warming Rate (RWR), is a measure of how rapidly the land warms relative to the overlying atmosphere during dry spells lasting at least 10 days. Under clear skies, this is a proxy for the change in sensible heat flux as soil dries out. We derived RWR from MODIS Terra and Aqua LST observations, meteorological re-analyses and satellite rainfall datasets. Globally we found that on average, the land warmed up during dry spells for 97% of the observed surface between 60S and 60N. For 73% of the area, the land warmed faster than the atmosphere (positive RWR), indicating water stressed conditions and increases in sensible heat flux

Growth behavior of laser-induced damage on fused silica optics under UV, ns laser irradiation.

Science.gov (United States)

Negres, Raluca A; Norton, Mary A; Cross, David A; Carr, Christopher W

2010-09-13

The growth behavior of laser-induced damage sites is affected by a large number of laser parameters as well as site morphology. Here we investigate the effects of pulse duration on the growth rate of damage sites located on the exit surface of fused silica optics. Results demonstrate a significant dependence of the growth parameters on laser pulse duration at 351 nm from 1 ns to 15 ns, including the observation of a dominant exponential versus linear, multiple-shot growth behavior for long and short pulses, respectively. These salient behaviors are tied to the damage morphology and suggest a shift in the fundamental growth mechanisms for pulses in the 1-5 ns range.

Long-term surface pCO2 trends from observations and models

International Nuclear Information System (INIS)

Tjiputra, Jerry F.; Olsen, Are; Heinze, Christoph; Bopp, Laurent; Roy, Tilla

2014-01-01

We estimate regional long-term surface ocean pCO 2 growth rates using all available underway and bottled biogeochemistry data collected over the past four decades. These observed regional trends are compared with those simulated by five state-of-the-art Earth system models over the historical period. Oceanic pCO 2 growth rates faster than the atmospheric growth rates indicate decreasing atmospheric CO 2 uptake, while ocean pCO 2 growth rates slower than the atmospheric growth rates indicate increasing atmospheric CO 2 uptake. Aside from the western sub-polar North Pacific and the subtropical North Atlantic, our analysis indicates that the current observation-based basin-scale trends may be underestimated, indicating that more observations are needed to determine the trends in these regions. Encouragingly, good agreement between the simulated and observed pCO 2 trends is found when the simulated fields are sub sampled with the observational coverage. In agreement with observations, we see that the simulated pCO 2 trends are primarily associated with the increase in surface dissolved inorganic carbon (DIC) associated with atmospheric carbon uptake, and in part by warming of the sea surface. Under the RCP8.5 future scenario, DIC continues to be the dominant driver of pCO 2 trends, with little change in the relative contribution of SST. However, the changes in the hydrological cycle play an increasingly important role. For the contemporary (1970-2011) period, the simulated regional pCO 2 trends are lower than the atmospheric growth rate over 90% of the ocean. However, by year 2100 more than 40% of the surface ocean area has a higher oceanic pCO 2 trend than the atmosphere, implying a reduction in the atmospheric CO 2 uptake rate. The fastest pCO 2 growth rates are projected for the sub-polar North Atlantic, while the high-latitude Southern Ocean and eastern equatorial Pacific have the weakest growth rates, remaining below the atmospheric pCO 2 growth rate. Our work

Long-term surface pCO2 trends from observations and models

Directory of Open Access Journals (Sweden)

Jerry F. Tjiputra

2014-05-01

Full Text Available We estimate regional long-term surface ocean pCO2 growth rates using all available underway and bottled biogeochemistry data collected over the past four decades. These observed regional trends are compared with those simulated by five state-of-the-art Earth system models over the historical period. Oceanic pCO2 growth rates faster than the atmospheric growth rates indicate decreasing atmospheric CO2 uptake, while ocean pCO2 growth rates slower than the atmospheric growth rates indicate increasing atmospheric CO2 uptake. Aside from the western subpolar North Pacific and the subtropical North Atlantic, our analysis indicates that the current observation-based basin-scale trends may be underestimated, indicating that more observations are needed to determine the trends in these regions. Encouragingly, good agreement between the simulated and observed pCO2 trends is found when the simulated fields are subsampled with the observational coverage. In agreement with observations, we see that the simulated pCO2 trends are primarily associated with the increase in surface dissolved inorganic carbon (DIC associated with atmospheric carbon uptake, and in part by warming of the sea surface. Under the RCP8.5 future scenario, DIC continues to be the dominant driver of pCO2 trends, with little change in the relative contribution of SST. However, the changes in the hydrological cycle play an increasingly important role. For the contemporary (1970–2011 period, the simulated regional pCO2 trends are lower than the atmospheric growth rate over 90% of the ocean. However, by year 2100 more than 40% of the surface ocean area has a higher oceanic pCO2 trend than the atmosphere, implying a reduction in the atmospheric CO2 uptake rate. The fastest pCO2 growth rates are projected for the subpolar North Atlantic, while the high-latitude Southern Ocean and eastern equatorial Pacific have the weakest growth rates, remaining below the atmospheric pCO2 growth rate. Our work

Effects of focused ion beam induced damage on the plasticity of micropillars

International Nuclear Information System (INIS)

El-Awady, Jaafar A.; Woodward, Christopher; Dimiduk, Dennis M.; Ghoniem, Nasr M.

2009-01-01

The hardening effects of focused ion beam (FIB) induced damage produced during the fabrication of micropillars are examined by introducing a surface layer of nanosized obstacles into a dislocation dynamics simulation. The influence of the depth and strength of the obstacles as a function of pillar diameter is assessed parametrically. We show that for a selected set of sample sizes between 0.5 and 1.0 μm, the flow strength can increase by 10-20 %, for an obstacle strength of 750 MPa, and damage depth of 100 nm. On the other hand, for sizes larger and smaller than this range, the effect of damage is negligible. Results show that the obstacles formed during the FIB milling may be expected to alter the microstructure of micropillars, however, they have a negligible effect on the observed size-strength scaling laws.

Observation of modified radiative properties of cold atoms in vacuum near a dielectric surface

International Nuclear Information System (INIS)

Ivanov, V V; Cornelussen, R A; Heuvell, H B van Linden van den; Spreeuw, R J C

2004-01-01

We have observed a distance-dependent absorption linewidth of cold 87 Rb atoms close to a dielectric-vacuum interface. This is the first observation of modified radiative properties in vacuum near a dielectric surface. A cloud of cold atoms was created using a magneto-optical trap (MOT) and optical molasses cooling. Evanescent waves (EW) were used to observe the behaviour of the atoms near the surface. We observed an increase of the absorption linewidth by up to 25% with respect to the free-space value. Approximately half the broadening can be explained by cavity quantum electrodynamics (CQED) as an increase of the natural linewidth and inhomogeneous broadening. The remainder we attribute to local Stark shifts near the surface. By varying the characteristic EW length we have observed a distance dependence characteristic for CQED

A comparison of atom and ion induced SSIMS - evidence for a charge induced damage effect in insulator materials

International Nuclear Information System (INIS)

Brown, A.; Berg, J.A. van den; Vickerman, J.C.

1985-01-01

A static secondary ion mass spectrometry (SSIMS) study of two very low conductivity materials, polystyrene and niobium pentoxide, using on the one hand a primary ion beam with electron neutralisation, and on the other, atom bombardment, shows that whilst the initial spectra obtained were quite similar, subsequent damage effects were much greater under ion impact conditions. For an equivalent flux density the half-life of the polystyrene surface structure was four times longer under atom bombardment. Significant reduction of the niobium surface was observed under ion bombardment whereas an equivalent atom flux had little apparent effect on the surface oxidation state. These data suggest that the requirement to dissipate the charge delivered to the sample by the primary ion beam contributes significantly to the damage mechanisms in electrically insulating materials. (author)

Quantification of high-power ultrasound induced damage on potato starch granules using light microscopy.

Science.gov (United States)

Zuo, Yue Yue J; Hébraud, Pascal; Hemar, Yacine; Ashokkumar, Muthupandian

2012-05-01

A simple light microscopic technique was developed in order to quantify the damage inflicted by high-power low-frequency ultrasound (0-160 W, 20 kHz) treatment on potato starch granules in aqueous dispersions. The surface properties of the starch granules were modified using ethanol and SDS washing methods, which are known to displace proteins and lipids from the surface of the starch granules. The study showed that in the case of normal and ethanol-washed potato starch dispersions, two linear regions were observed. The number of defects first increased linearly with an increase in ultrasound power up to a threshold level. This was then followed by another linear dependence of the number of defects on the ultrasound power. The power threshold where the change-over occurred was higher for the ethanol-washed potato dispersions compared to non-washed potato dispersions. In the case of SDS-washed potato starch, although the increase in defects was linear with the ultrasound power, the power threshold for a second linear region was not observed. These results are discussed in terms of the different possible mechanisms of cavitation induced-damage (hydrodynamic shear stresses and micro-jetting) and by taking into account the hydrophobicity of the starch granule surface. Copyright © 2011 Elsevier B.V. All rights reserved.

MIGRATION OF CU ADATOMS ON A CU(100) SURFACE, STUDIED WITH LOW-ENERGY ION-SCATTERING (LEIS)

NARCIS (Netherlands)

BREEMAN, M; BOERMA, DO

1992-01-01

We report the observation of adatoms appearing on the surface due to ion beam irradiation. These adatoms are interpreted to be self-interstitials, created in the damage cascades, which have diffused to the surface where they are trapped. From our LEIS experiments on a stepped Cu(100) surface we

Observation of hidden Fermi surface nesting in a two dimensional conductor

International Nuclear Information System (INIS)

Breuer, K.; Stagerescu, C.; Smith, K.E.; Greenblatt, M.; Ramanujachary, K.

1996-01-01

We report the first direct measurement of hidden Fermi surface nesting in a two dimensional conductor. The system studied was Na 0.9 Mo 6 O 17 , and the measured Fermi surface consists of electron and hole pockets that can be combined to form sets of pseudo-one-dimensional Fermi surfaces, exhibiting the nesting necessary to drive a Peierls transition to a charge density wave state. The observed nesting vector is shown to be in excellent agreement with theory. copyright 1996 The American Physical Society

Damage and fracture in large aperture, fused silica, vacuum spatial filter lenses

International Nuclear Information System (INIS)

Campbell, J.H.; Edwards, G.J.; Marion, J.E.

1995-01-01

Optical damage that results in large scale fracture has been observed in the large, high-fluence, fused-silica, spatial filter lenses on the Nova and Beamlet lasers. In nearly all cases damage occurs on the vacuum side of the lenses and because the vacuum side of the lens is under tensile stress this damage can lead to catastrophic crack growth if the flaw (damage) size exceeds the critical flaw size for SiO 2 . The damaged 52 cm Nova lenses fracture into two and sometimes three large pieces. Although under full vacuum load at the time they fracture, the Nova lenses do not implode. Rather the authors have observed that the pieces lock together and air slowly leaks into the vacuum spatial filter housing through the lens cracks. The Beamlet lenses have a larger aspect ratio and peak tensile stress than Nova. The peak tensile stress at the center of the output surface of the Beamlet lens is 1,490 psi versus 810 psi for Nova. During a recent Beamlet high energy shot, a damage spot on the lens grew to the critical flaw size and the lens imploded. Post shot data indicate the lens probably fractured into 5 to 7 pieces, however, unlike Nova, these pieces did not lock together. Analysis shows that the likely source of damage is contamination from pinhole blow-off or out-gassing of volatile materials within the spatial filter. Contamination degrades the antireflection properties of the sol-gel coating and reduces its damage threshold. By changing the design of the Beamlet lens it may be possible to insure that it fails safe by locking up in much that same manner as the Nova lens

SEM observations of particle track membrane surfaces modificated using plasma treatment

International Nuclear Information System (INIS)

Sartowska, B.; Buczkowski, M.; Starosta, W.

2003-01-01

This work presents results of scanning electron microscopy (SEM) observations of 0.4 μm membranes after plasma treatment with different parameters. The morphology changes at the surfaces and at the pore walls were observed. The character of changes in the membrane parameters according to the process conditions was determined

STS Observations of Landau Levels at Graphite Surfaces

OpenAIRE

Matsui, T.; Kambara, H.; Niimi, Y.; Tagami, K.; Tsukada, M.; Fukuyama, Hiroshi

2004-01-01

Scanning tunneling spectroscopy measurements were made on surfaces of two different kinds of graphite samples, Kish graphite and highly oriented pyrolytic graphite (HOPG), at very low temperatures and in high magnetic fields. We observed a series of peaks in the tunnel spectra, which grow with increasing field, both at positive and negative bias voltages. These are associated with Landau quantization of the quasi two-dimensional electrons and holes in graphite in magnetic fields perpendicular...

Structural damage and chemical contaminants on reprocessed arthroscopic shaver blades.

Science.gov (United States)

Kobayashi, Masahiko; Nakagawa, Yasuaki; Okamoto, Yukihiro; Nakamura, Shinichiro; Nakamura, Takashi

2009-02-01

In response to socioeconomic pressure to cut budgets in medicine, single-use surgical instruments are often reprocessed despite potential biological hazard. To evaluate the quality and contaminants of reprocessed shaver blades. Reprocessed shaver blades have mechanical damage and chemical contamination. Controlled laboratory study. Seven blades and 3 abraders were reprocessed 1 time or 3 times and then were assessed. In the first part of the study, structural damage on the blades after 3 reprocessings was compared to that after 1 reprocessing using optical microscopy. In the second part, surface damage was observed using optical microscopy and scanning electron microscopy; elemental and chemical analyses of contaminants found by the microscopy were performed using scanning electron microscopy/energy dispersive x-ray spectroscopy, scanning Auger microscopy, and Fourier transform infrared spectroscopy. Optical microscopic examination revealed abrasion on the surface of the inner blade and cracks on the inner tube after 1 reprocessing. These changes were more evident after 3 reprocessings. Scanning electron microscopy/energy dispersive x-ray spectroscopy of the inner cutter of the blade reprocessed once showed contaminants containing calcium, carbon, oxygen, and silicon, and Fourier transform infrared spectroscopy demonstrated biological protein consisting mainly of collagen, some type of salts, and polycarbonate used in plastic molding. Scanning electron microscopy/energy dispersive x-ray spectroscopy of the inner cutter of the reprocessed abrader revealed contaminants containing carbon, calcium, phosphorous, and oxygen, and Fourier transform infrared spectroscopy showed H2O, hydroxyapatite, and hydroxyl proteins. Scanning Auger microscopy showed that the tin-nickel plating on the moving blade and abrader was missing in some locations. This is the first study to evaluate both mechanical damage and chemical contaminants containing collagen, hydroxyapatite, and salts

Morphologies of laser-induced damage in hafnia-silica multilayer mirror and polarizer coatings

International Nuclear Information System (INIS)

Genin, F.Y.; Stolz, C.J.

1996-08-01

Hafnium-silica multilayer mirrors and polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The mirrors and polarizers were coated for operation at 1053 nm at 45 degree and at Brewster's angle (56 degree), respectively. They were tested with a single 3-ns laser pulse. Morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies were found: pits, flatbottom pits, scalds, and delaminates. The pits and flat bottom pits ( 2 ). The pits seemed to result from ejection of nodular defects by causing local enhancement of the electric field. Scalds and delaminates could be observed at higher fluences (above 13 J/cm 2 ) and seemed to result from the formation of plasmas on the surface. These damage types often originated at pits and were less than 300 μm diameter; their size increased almost linearly with fluence. Finally, effects of the damage on the beam (reflectivity degradation and phase modulations) were measured

Surface morphologies of He-implanted tungsten

Energy Technology Data Exchange (ETDEWEB)

Bannister, M.E., E-mail: bannisterme@ornl.gov [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6371 (United States); Meyer, F.W.; Hijazi, H. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6371 (United States); Unocic, K.A.; Garrison, L.M.; Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

2016-09-01

Surface morphologies of tungsten surfaces, both polycrystalline and single-crystal [1 1 0], were investigated using SEM and FIB/SEM techniques after implantations at elevated surfaces temperatures (1200–1300 K) using well-characterized, mono-energetic He ion beams with a wide range of ion energies (218 eV–250 keV). Nanofuzz was observed on polycrystalline tungsten (PCW) following implantation of 100-keV He ions at a flux threshold of 0.9 × 10{sup 16} cm{sup −2} s{sup −1}, but not following 200-keV implantations with similar fluxes. No nanofuzz formation was observed on single-crystal [1 1 0] tungsten (SCW), despite fluxes exceeding those demonstrated previously to produce nanofuzz on polycrystalline tungsten. Pre-damaging the single-crystal tungsten with implanted C impurity interstitials did not significantly affect the surface morphologies resulting from the high-flux He ion implantations. The main factor leading to the different observed surface structures for the pristine and C-implanted single-crystal W samples appeared to be the peak He ion flux characterizing the different exposures. It was speculated that nanofuzz formation was not observed for any SCW target exposures because of increased incubation fluences required for such targets.

Radiation response of alloy T91 at damage levels up to 1000 peak dpa

Energy Technology Data Exchange (ETDEWEB)

Gigax, J. G.; Chen, T.; Kim, Hyosim; Wang, J.; Price, L. M.; Aydogan, E.; Maloy, S. A.; Schreiber, D. K.; Toloczko, M. B.; Garner, F. A.; Shao, Lin

2016-12-01

Ferritic/martensitic alloys are required for advanced reactor components to survive 500e600 neutroninduced dpa. Ion-induced void swelling of ferritic/martensitic alloy T91 in the quenched and tempered condition has been studied using a defocused, non-rastered 3.5 MeV Fe-ion beam at 475 C to produce damage levels up to 1000 peak displacements per atom (dpa). The high peak damage level of 1000 dpa is required to reach 500e600 dpa level due to injected interstitial suppression of void nucleation in the peak dpa region, requiring data extraction closer to the surface at lower dpa levels. At a relatively low peak damage level of 250 dpa, voids began to develop, appearing first in the near-surface region. With increasing ion fluence, swelling was observed deeper in the specimen, but remained completely suppressed in the back half of the ion range, even at 1000 peak dpa. The local differences in dpa rate in the front half of the ion range induce an “internal temperature shift” that strongly influences the onset of swelling, with shorter transient regimes resulting from lower dpa rates, in agreement not only with observations in neutron irradiation studies but also in various ion irradiations. Swelling was accompanied by radiation-induced precipitation of Cu-rich and Si, Ni, Mn-rich phases were observed by atom probe tomography, indicating concurrent microchemical evolution was in progress. In comparison to other ferritic/martensitic alloys during ion irradiation, T91 exhibits good swelling resistance with a swelling incubation period of about 400 local dpa.

Exploring the potential of multivariate depth-damage and rainfall-damage models

DEFF Research Database (Denmark)

van Ootegem, Luc; van Herck, K.; Creten, T.

2018-01-01

In Europe, floods are among the natural catastrophes that cause the largest economic damage. This article explores the potential of two distinct types of multivariate flood damage models: ‘depth-damage’ models and ‘rainfall-damage’ models. We use survey data of 346 Flemish households that were...... victim of pluvial floods complemented with rainfall data from both rain gauges and weather radars. In the econometrical analysis, a Tobit estimation technique is used to deal with the issue of zero damage observations. The results show that in the ‘depth-damage’ models flood depth has a significant...... impact on the damage. In the ‘rainfall-damage’ models there is a significant impact of rainfall accumulation on the damage when using the gauge rainfall data as predictor, but not when using the radar rainfall data. Finally, non-hazard indicators are found to be important for explaining pluvial flood...

Sensitivity of surface meteorological analyses to observation networks

Science.gov (United States)

Tyndall, Daniel Paul

A computationally efficient variational analysis system for two-dimensional meteorological fields is developed and described. This analysis approach is most efficient when the number of analysis grid points is much larger than the number of available observations, such as for large domain mesoscale analyses. The analysis system is developed using MATLAB software and can take advantage of multiple processors or processor cores. A version of the analysis system has been exported as a platform independent application (i.e., can be run on Windows, Linux, or Macintosh OS X desktop computers without a MATLAB license) with input/output operations handled by commonly available internet software combined with data archives at the University of Utah. The impact of observation networks on the meteorological analyses is assessed by utilizing a percentile ranking of individual observation sensitivity and impact, which is computed by using the adjoint of the variational surface assimilation system. This methodology is demonstrated using a case study of the analysis from 1400 UTC 27 October 2010 over the entire contiguous United States domain. The sensitivity of this approach to the dependence of the background error covariance on observation density is examined. Observation sensitivity and impact provide insight on the influence of observations from heterogeneous observing networks as well as serve as objective metrics for quality control procedures that may help to identify stations with significant siting, reporting, or representativeness issues.

Evaluation of fatigue damage of pressure vessel materials by observation of microstructures

International Nuclear Information System (INIS)

Yoshida, Kazuo

1994-01-01

As the important factor as the secular change mode of pressure vessel materials, there is fatigue damage. In USA, there is the move to use LWRs by extending their life, and it becomes necessary to show the soundness of the structures of machinery and equipment for long period. For exactly evaluating the soundness of the structures of machinery and equipment, it is important to clarify the degree of secular deterioration of the materials. In this report, by limiting to the fatigue damage of LWR pressure vessel steel, the method of grasping the change of microstructure and the method of estimating the degree of fatigue damage from the change of microstructure are shown. The change of microstructure arising in materials due to fatigue advances in the following steps, namely, the multiplication of dislocations, the tangling of dislocations, the formation of cell structure, the turning of cells, the formation of microcracks, the growth of cracks and fracture. In the case of pressure vessel steel, due to the quenching and tempering, the cell structure is formed from the beginning, and the advance of fatigue is recognized as the increase of the turning angle of cell structures. The detection of fatigue damage by microstructure is reported. (K.I.)

The Fracture of Plasma-Treated Polyurethane Surface under Fatigue Loading

Directory of Open Access Journals (Sweden)

Ilya A. Morozov

2018-02-01

Full Text Available Plasma treatment of soft polymers is a promising technique to improve biomedical properties of the materials. The response to the deformation of such materials is not yet clear. Soft elastic polyurethane treated with plasma immersion ion implantation is subjected to fatigue uniaxial loading. The influence of the strain amplitude and the plasma treatment regime on damage character is discussed. Surface defects are studied in unloaded and stretched states of the material. As a result of fatigue loading, transverse cracks (with closed overlapping edges as well as with open edges deeply propagating into the polymer and longitudinal folds which are break and bend inward, appear on the surface. Hard edges of cracks cut the soft polymer which is squeezed from the bulk to the surface. The observed damages are related to the high stiffness of the modified surface and its transition to the polymer substrate.

Structural and electrical characterization of HBr/O2 plasma damage to Si substrate

International Nuclear Information System (INIS)

Fukasawa, Masanaga; Nakakubo, Yoshinori; Matsuda, Asahiko; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi; Minami, Masaki; Uesawa, Fumikatsu; Tatsumi, Tetsuya

2011-01-01

Silicon substrate damage caused by HBr/O 2 plasma exposure was investigated by spectroscopic ellipsometry (SE), high-resolution Rutherford backscattering spectroscopy, and transmission electron microscopy. The damage caused by H 2 , Ar, and O 2 plasma exposure was also compared to clarify the ion-species dependence. Although the damage basically consists of a surface oxidized layer and underlying dislocated Si, the damage structure strongly depends on the incident ion species, ion energy, and oxidation during air and plasma exposure. In the case of HBr/O 2 plasma exposure, hydrogen generated the deep damaged layer (∼10 nm), whereas ion-enhanced diffusion of oxygen, supplied simultaneously by the plasma, caused the thick surface oxidation. In-line monitoring of damage thicknesses by SE, developed with an optimized optical model, showed that the SE can be used to precisely monitor damage thicknesses in mass production. Capacitance-voltage (C-V) characteristics of a damaged layer were studied before and after diluted-HF (DHF) treatment. Results showed that a positive charge is generated at the surface oxide-dislocated Si interface and/or in the bulk oxide after plasma exposure. After DHF treatment, most of the positive charges were removed, while the thickness of the ''Si recess'' was increased by removing the thick surface oxidized layer. As both the Si recess and remaining dislocated Si, including positive charges, cause the degradation of electrical performance, precise monitoring of the surface structure and understanding its effect on device performance is indispensable for creating advanced devices.

The role of implantation damage in the production of silicon-on-insulator films by co-implantation of He+ and H+

International Nuclear Information System (INIS)

Venezia, V.C.; Agarwal, A.; Lucent Technologies, Murray Hill, NJ; Haynes, T.E.; Holland, O.W.; Eaglesham, D.J.; Weldon, M.K.; Chabal, Y.J.

1998-01-01

Recent work has demonstrated that the process of silicon thin film separation by hydrogen implantation, as well as the more basic phenomenon of surface blistering, can occur at a much lower total dose when H and He are co-implanted than when H is implanted alone. Building on that work, this paper investigates the role of implantation damage in this process by separating the contributions of gas pressure from those of damage. Three different experiments using co-implantation were designed. In the first of these experiments, H and He implants were spatially separated thereby separating the damage from each implant. The second experiment involved co-implantation of H and He at a temperature of 77 K to retain a larger amount of damage for the same gas dose. In the third experiment, Li was co-implanted with H, to create additional damage without introducing additional gas. These experiments together show that increasing the implantation damage itself hampers the formation of surface blisters, and that the increased efficiency observed for He co-implantation with H is due to the supplementary source of gas provided by the He

Assessment of DNA damages caused by exposure of bacterial cells and spores to the Mars surface environment

Science.gov (United States)

Fajardo-Cavazos, Patricia; Schuerger, Andrew; Robles-Martinez, Jose; Douki, Thierry; Nicholson, Wayne

Joint NASA and ESA missions are planned for the next decade to investigate the possibility of present or past life on Mars [1]. Evidence of extraterrestrial life will likely rely on the de-tection of biomarkers, highlighting the importance of preventing forward contamination not only with viable microorganisms, but also with biomolecules that could compromise the valid-ity of life-detection experiments [2-4]. The designation of DNA as a high-priority biomarker makes it necessary to evaluate its persistence in extraterrestrial environments, and the effects of exposure on its biological activity. To accomplish this, we deposited naked DNA, cells and spores of Bacillus subtilis 168 or B. pumilus SAFR-032, or cells of Acinetobacter radioresistens 50v1 onto spacecraft-qualified aluminum coupons. Samples were exposed to a simulated Mars surface environment as described in detail previously [4, 5] for various periods of time, and DNA damage was assessed by a number of measurements. Double-and single-strand breaks were measured by neutral and alkaline agarose gel electrophoresis, and DNA bipyrimidine pho-toproducts were measured by HPLC-mass spectrometry, as described previously [6, 7]. Loss of functionality of DNA to serve as a template for replication by DNA polymerase was measured using a quantitative polymerase chain reaction (qPCR) assay [8]. In all cases, DNA damage was directly correlated with time of exposure to simulated martian solar radiation (UV, visible, and infrared wavelengths). Exposure of samples to Mars surface conditions, but shielded from solar radiation, did not result in appreciable damage over the time periods tested, relative to controls. DNA contained within cells or spores was much less susceptible to damage than was naked DNA. Using the qPCR assay, we found that inactivation of naked DNA or DNA extracted from exposed spores of B. subtilis followed a multiphasic dose-response, and that a fraction of DNA molecules retained functionality after

Damage evolution of TBC system under in-phase thermo-mechanical tests

International Nuclear Information System (INIS)

Kitazawa, R.; Tanaka, M.; Kagawa, Y.; Liu, Y.F.

2010-01-01

In-phase thermo-mechanical tests (TMF) of EB-PVD Y 2 O 3 -ZrO 2 thermal barrier coating (TBC) system (8 wt% Y 2 O 3 -ZrO 2 /CoNiCrAlY/IN-738 substrate) were done under a through-the-thick-direction thermal gradient from TBC surface temperature at 1150 deg. C to substrate temperature at 1000 deg. C. Deformation and failure behaviors of the TBC system were observed at the macroscopic and microscopic scales and damage evolution of the system under in-phase thermo-mechanical test was discussed. Special attention was paid to TBC layer cracking, thermally grown oxide (TGO) layer formation and void formation in bond coat and substrate. Effect of TMF conditions on the damage evolution behaviors was also discussed.

Suzaku observations of low surface brightness cluster Abell 1631

Science.gov (United States)

Babazaki, Yasunori; Mitsuishi, Ikuyuki; Ota, Naomi; Sasaki, Shin; Böhringer, Hans; Chon, Gayoung; Pratt, Gabriel W.; Matsumoto, Hironori

2018-04-01

We present analysis results for a nearby galaxy cluster Abell 1631 at z = 0.046 using the X-ray observatory Suzaku. This cluster is categorized as a low X-ray surface brightness cluster. To study the dynamical state of the cluster, we conduct four-pointed Suzaku observations and investigate physical properties of the Mpc-scale hot gas associated with the A 1631 cluster for the first time. Unlike relaxed clusters, the X-ray image shows no strong peak at the center and an irregular morphology. We perform spectral analysis and investigate the radial profiles of the gas temperature, density, and entropy out to approximately 1.5 Mpc in the east, north, west, and south directions by combining with the XMM-Newton data archive. The measured gas density in the central region is relatively low (a few ×10-4 cm-3) at the given temperature (˜2.9 keV) compared with X-ray-selected clusters. The entropy profile and value within the central region (r < 0.1 r200) are found to be flatter and higher (≳400 keV cm2). The observed bolometric luminosity is approximately three times lower than that expected from the luminosity-temperature relation in previous studies of relaxed clusters. These features are also observed in another low surface brightness cluster, Abell 76. The spatial distributions of galaxies and the hot gas appear to be different. The X-ray luminosity is relatively lower than that expected from the velocity dispersion. A post-merger scenario may explain the observed results.

Suzaku observations of low surface brightness cluster Abell 1631

Science.gov (United States)

Babazaki, Yasunori; Mitsuishi, Ikuyuki; Ota, Naomi; Sasaki, Shin; Böhringer, Hans; Chon, Gayoung; Pratt, Gabriel W.; Matsumoto, Hironori

2018-06-01

We present analysis results for a nearby galaxy cluster Abell 1631 at z = 0.046 using the X-ray observatory Suzaku. This cluster is categorized as a low X-ray surface brightness cluster. To study the dynamical state of the cluster, we conduct four-pointed Suzaku observations and investigate physical properties of the Mpc-scale hot gas associated with the A 1631 cluster for the first time. Unlike relaxed clusters, the X-ray image shows no strong peak at the center and an irregular morphology. We perform spectral analysis and investigate the radial profiles of the gas temperature, density, and entropy out to approximately 1.5 Mpc in the east, north, west, and south directions by combining with the XMM-Newton data archive. The measured gas density in the central region is relatively low (a few ×10-4 cm-3) at the given temperature (˜2.9 keV) compared with X-ray-selected clusters. The entropy profile and value within the central region (r clusters. These features are also observed in another low surface brightness cluster, Abell 76. The spatial distributions of galaxies and the hot gas appear to be different. The X-ray luminosity is relatively lower than that expected from the velocity dispersion. A post-merger scenario may explain the observed results.

Separation of surface, subsurface and volume fatigue damage effects in AISI 348 steel for power plant applications

Energy Technology Data Exchange (ETDEWEB)

Klein, Martin; Nowak, David; Walther, Frank [Technical Univ. Dortmund (Germany). Dept. of Materials Test Engineering (WPT); Starke, Peter [Saarland Univ., Saarbruecken (Germany). Chair of Non-Destructive Testing and Quality Assurance; Boller, Christian [Saarland Univ., Saarbruecken (Germany). Chair of Non-Destructive Testing and Quality Assurance; Fraunhofer IZFP, Saarbruecken (Germany)

2016-08-01

A wide range of industries including energy, chemistry, pharmacy, textiles, food and drink, pulp and paper, etc. is using stainless steels. Metastable austenitic steels such as used in power plants and chemical industry are subjected to cyclic mechanical and thermal loading in air as well as under the influence of corrosive media. This paper provides an overview on different nondestructive and electrochemical measurement techniques, which allow differentiating fatigue damage effects in total strain controlled multiple and constant amplitude tests with respect to damage appearance on surface, in subsurface area as well as in volume of specimens or components microstructure. In addition to conventional mechanical stress-strain hysteresis curves, electrical resistance, magnetic and open circuit potential measurements have been applied to characterize the cyclic deformation behavior of the metastable austenitic steel AISI 348 (X10CrNiNb18-9) in laboratory air and in distilled water. Based on these results obtained, the paper provides an outlook on the possibility for an efficient (remaining) fatigue life evaluation approach, which is adapted to the needs of the application areas.

Development of Innovative Technology to Provide Low-Cost Surface Atmospheric Observations

Science.gov (United States)

Kucera, Paul; Steinson, Martin

2016-04-01

Accurate and reliable real-time monitoring and dissemination of observations of surface weather conditions is critical for a variety of societal applications. Applications that provide local and regional information about temperature, precipitation, moisture, and winds, for example, are important for agriculture, water resource monitoring, health, and monitoring of hazard weather conditions. In many regions in Africa (and other global locations), surface weather stations are sparsely located and/or of poor quality. Existing stations have often been sited incorrectly, not well-maintained, and have limited communications established at the site for real-time monitoring. The US National Weather Service (NWS) International Activities Office (IAO) in partnership with University Corporation for Atmospheric Research (UCAR)/National Center for Atmospheric Research (NCAR) and funded by the United States Agency for International Development (USAID) Office of Foreign Disaster Assistance (OFDA) has started an initiative to develop and deploy low-cost weather instrumentation in sparsely observed regions of the world. The goal is to provide observations for environmental monitoring, and early warning alert systems that can be deployed at weather services in developing countries. Instrumentation is being designed using innovative new technologies such as 3D printers, Raspberry Pi computing systems, and wireless communications. The initial effort is focused on designing a surface network using GIS-based tools, deploying an initial network in Zambia, and providing training to Zambia Meteorological Department (ZMD) staff. The presentation will provide an overview of the project concepts, design of the low cost instrumentation, and initial experiences deploying a surface network deployment in Zambia.

Asian Dust Weather Categorization with Satellite and Surface Observations

Science.gov (United States)

Lin, Tang-Huang; Hsu, N. Christina; Tsay, Si-Chee; Huang, Shih-Jen

2011-01-01

This study categorizes various dust weather types by means of satellite remote sensing over central Asia. Airborne dust particles can be identified by satellite remote sensing because of the different optical properties exhibited by coarse and fine particles (i.e. varying particle sizes). If a correlation can be established between the retrieved aerosol optical properties and surface visibility, the intensity of dust weather can be more effectively and consistently discerned using satellite rather than surface observations. In this article, datasets consisting of collocated products from Moderate Resolution Imaging Spectroradiometer Aqua and surface measurements are analysed. The results indicate an exponential relationship between the surface visibility and the satellite-retrieved aerosol optical depth, which is subsequently used to categorize the dust weather. The satellite-derived spatial frequency distributions in the dust weather types are consistent with China s weather station reports during 2003, indicating that dust weather classification using satellite data is highly feasible. Although the period during the springtime from 2004 to 2007 may be not sufficient for statistical significance, our results reveal an increasing tendency in both intensity and frequency of dust weather over central Asia during this time period.

Coal transportation road damage

International Nuclear Information System (INIS)

Burtraw, D.; Harrison, K.; Pawlowski, J.A.

1994-01-01

Heavy trucks are primarily responsible for pavement damage to the nation's highways. In this paper we evaluate the pavement damage caused by coal trucks. We analyze the chief source of pavement damage (vehicle weight per axle, not total vehicle weight) and the chief cost involved (the periodic overlay that is required when a road's surface becomes worn). This analysis is presented in two stages. In the first section we present a synopsis of current economic theory including simple versions of the formulas that can be: used to calculate costs of pavement wear. In the second section we apply this theory to a specific example proximate to the reference environment for the Fuel Cycle Study in New Mexico in order to provide a numerical measure of the magnitude of the costs

Short-pulse CO2-laser damage studies of NaCl and KCl windows

International Nuclear Information System (INIS)

Newnam, B.E.; Nowak, A.V.; Gill, D.H.

1979-01-01

The damage resistance of bare surfaces and the bulk interior of NaCl and KCl windows was measured with a short-pulse CO 2 laser at 10.6 μm. Parametric studies with 1.7-ns pulses indicated that adsorbed water was probably the limiting agent on surface thresholds in agreement with previous studies at long pulsewidths. Rear-surface thresholds up to 7 J/cm 2 were measured for polished NaCl windows, whereas KCl surfaces damaged at approximately 60% of this level. The breakdown electric-field thresholds of exit surfaces were only 50% of the value of the bulk materials. The pulsewidth dependence of surface damage from 1 to 65 ns, in terms of incident laser fluence, increased as t/sup 1/3/

Surface net solar radiation estimated from satellite measurements - Comparisons with tower observations

Science.gov (United States)

Li, Zhanqing; Leighton, H. G.; Cess, Robert D.

1993-01-01

A parameterization that relates the reflected solar flux at the top of the atmosphere to the net solar flux at the surface in terms of only the column water vapor amount and the solar zenith angle was tested against surface observations. Net surface fluxes deduced from coincidental collocated satellite-measured radiances and from measurements from towers in Boulder during summer and near Saskatoon in winter have mean differences of about 2 W/sq m, regardless of whether the sky is clear or cloudy. Furthermore, comparisons between the net fluxes deduced from the parameterization and from surface measurements showed equally good agreement when the data were partitioned into morning and afternoon observations. This is in contrast to results from an empirical clear-sky algorithm that is unable to account adequately for the effects of clouds and that shows, at Boulder, a distinct morning to afternoon variation. It is also demonstrated that the parameterization may be applied to irradiances at the top of the atmosphere that have been temporally averaged. The good agreement between the results of the parameterization and surface measurements suggests that the algorithm is a useful tool for a variety of climate studies.

Radiation damage to nucleoprotein complexes in macromolecular crystallography

International Nuclear Information System (INIS)

Bury, Charles; Garman, Elspeth F.; Ginn, Helen Mary; Ravelli, Raimond B. G.; Carmichael, Ian; Kneale, Geoff; McGeehan, John E.

2015-01-01

Quantitative X-ray induced radiation damage studies employing a model protein–DNA complex revealed a striking partition of damage sites. The DNA component was observed to be far more resistant to specific damage compared with the protein. Significant progress has been made in macromolecular crystallography over recent years in both the understanding and mitigation of X-ray induced radiation damage when collecting diffraction data from crystalline proteins. In contrast, despite the large field that is productively engaged in the study of radiation chemistry of nucleic acids, particularly of DNA, there are currently very few X-ray crystallographic studies on radiation damage mechanisms in nucleic acids. Quantitative comparison of damage to protein and DNA crystals separately is challenging, but many of the issues are circumvented by studying pre-formed biological nucleoprotein complexes where direct comparison of each component can be made under the same controlled conditions. Here a model protein–DNA complex C.Esp1396I is employed to investigate specific damage mechanisms for protein and DNA in a biologically relevant complex over a large dose range (2.07–44.63 MGy). In order to allow a quantitative analysis of radiation damage sites from a complex series of macromolecular diffraction data, a computational method has been developed that is generally applicable to the field. Typical specific damage was observed for both the protein on particular amino acids and for the DNA on, for example, the cleavage of base-sugar N 1 —C and sugar-phosphate C—O bonds. Strikingly the DNA component was determined to be far more resistant to specific damage than the protein for the investigated dose range. At low doses the protein was observed to be susceptible to radiation damage while the DNA was far more resistant, damage only being observed at significantly higher doses

Electron Beam Damage in Poly(Vinyl Chloride) and Poly(Acrylonitrile) as Observed by Auger Electron Spectroscopy

International Nuclear Information System (INIS)

Lea, Alan S.; Engelhard, Mark H.; Baer, Donald R.

2003-01-01

AES spectra of spun-cast films of poly(vinyl chloride) (PVC) and poly(acrylonitrile) (PAN) were collected over a period of time to determine specimen damage during exposure to a 10kV electron beam. For the PVC, loss of chlorine was observed over a period of 203 minutes to the extent that the final chlorine concentration was only 20% of its original value. PAN exhibited a loss in nitrogen content over a period of 120 minutes, but the rate of damage to the polymer was significantly less than PVC. Figure 1 shows the atomic concentration in the PVC film as a function of dose (time). It takes a dose of approximately 7.0x10-5 Ccm-5 for the chlorine concentration to fall from its original value by 10% (one definition of critical dose). Figure 2 shows a similar drop in nitrogen concentration in the PAN film as a function of dose. For this polymer, it takes a dose of 1.3x10-3 Ccm-2 for the nitrogen concentration to fall by 10%

Offshore Wind Energy: Wind and Sea Surface Temperature from Satellite Observations

DEFF Research Database (Denmark)

Karagali, Ioanna

as the entire atmosphere above. Under conditions of light winds and strong solar insolation, warming of the upper oceanic layer may occur. In this PhD study, remote sensing from satellites is used to obtain information for the near-surface ocean wind and the sea surface temperature over the North Sea......, demonstrate that wind information from SAR is more appropriate when small scale local features are of interest, not resolved by scatterometers. Hourly satellite observations of the sea surface temperature, from a thermal infra-red sensor, are used to identify and quantify the daily variability of the sea...

Method to reduce damage to backing plate

Science.gov (United States)

Perry, Michael D.; Banks, Paul S.; Stuart, Brent C.

2001-01-01

The present invention is a method for penetrating a workpiece using an ultra-short pulse laser beam without causing damage to subsequent surfaces facing the laser. Several embodiments are shown which place holes in fuel injectors without damaging the back surface of the sack in which the fuel is ejected. In one embodiment, pulses from an ultra short pulse laser remove about 10 nm to 1000 nm of material per pulse. In one embodiment, a plasma source is attached to the fuel injector and initiated by common methods such as microwave energy. In another embodiment of the invention, the sack void is filled with a solid. In one other embodiment, a high viscosity liquid is placed within the sack. In general, high-viscosity liquids preferably used in this invention should have a high damage threshold and have a diffusing property.

Graphite surface topography induced by Ta cluster impact and oxidative etching

International Nuclear Information System (INIS)

Reimann, C.T.; Olsson, L.; Erlandsson, R.; Henkel, M.; Urbassek, H.M.

1998-01-01

Freshly cleaved highly oriented pyrolytic graphite (HOPG), when baked in air at ∝630 C, forms one-monolayer(ML)-deep circular pits due to oxidation initiated at surface defect sites. We found that the areal density and depths of these pits could be modulated by deliberately introducing surface and sub-surface defects by energetic ion bombardment prior to baking. Bombardment by 555-eV/atom Ta 1 + , Ta 2 + , Ta 4 + , or Ta 9 + , always enhanced the areal density of etch pits, but only bombardment by Ta 4 + , or Ta 9 + significantly enhanced the depths of the pits. We performed molecular dynamics simulations of Ta n cluster bombardment of HOPG (n = 1, 2, 4, and 9) with the aim of characterizing the damage structures induced by the bombardment and correlating them with the experimental data. For Ta 9 + , the simulations showed a high level of damage extending from the surface down to nine MLs, in agreement with the most probable etch pit depth observed. For other cluster species, predicted etch pit depths were deeper than the observed ones. Annealing or steric requirements for initiating oxidation may account for some of the differences between simulations and experimental results. (orig.)

Critical parameters influencing the EUV-induced damage of Ru-capped multilayer mirrors

International Nuclear Information System (INIS)

Hill, S B; Ermanoski, I; Tarrio, C; Lucatorto, T B; Madey, T E; Bajt, S; Fang, M; Chandhok, M

2007-01-01

Ongoing endurance testing of Ru-capped multilayer mirrors (MLMs) at the NIST synchrotron facility has revealed that the damage resulting from EUV irradiation does not always depend on the exposure conditions in an intuitive way. Previous exposures of Ru-capped MLMs to EUV radiation in the presence of water vapor demonstrated that the mirror damage rate actually decreases with increasing water pressure. We will present results of recent exposures showing that the reduction in damage for partial pressures of water up to 5 x 10 -6 Torr is not the result of a spatially uniform decrease in damage across the Gaussian intensity distribution of the incident EUV beam. Instead we observe a drop in the damage rate in the center of the exposure spot where the intensity is greatest, while the reflectivity loss in the wings of the intensity distribution appears to be independent of water partial pressure. (See Fig. 1.) We will discuss how the overall damage rate and spatial profile can be influenced by admixtures of carbon-containing species (e.g., CO, CO 2 , C 6 H 6 ) at partial pressures one-to-two orders of magnitude lower than the water vapor partial pressure. An investigation is underway to find the cause of the non-Gaussian damage profile. Preliminary results and hypotheses will be discussed. In addition to high-resolution reflectometry of the EUV-exposure sites, the results of surface analysis such as XPS will be presented. We will also discuss how the bandwidth and time structure of incident EUV radiation may affect the rate of reflectivity degradation. Although the observations presented here are based on exposures of Ru-capped MLMs, unless novel capping layers are similarly characterized, direct application of accelerated testing results could significantly overestimate mirror lifetime in the production environment

Attribution of observed surface humidity changes to human influence.

Science.gov (United States)

Willett, Katharine M; Gillett, Nathan P; Jones, Philip D; Thorne, Peter W

2007-10-11

Water vapour is the most important contributor to the natural greenhouse effect, and the amount of water vapour in the atmosphere is expected to increase under conditions of greenhouse-gas-induced warming, leading to a significant feedback on anthropogenic climate change. Theoretical and modelling studies predict that relative humidity will remain approximately constant at the global scale as the climate warms, leading to an increase in specific humidity. Although significant increases in surface specific humidity have been identified in several regions, and on the global scale in non-homogenized data, it has not been shown whether these changes are due to natural or human influences on climate. Here we use a new quality-controlled and homogenized gridded observational data set of surface humidity, with output from a coupled climate model, to identify and explore the causes of changes in surface specific humidity over the late twentieth century. We identify a significant global-scale increase in surface specific humidity that is attributable mainly to human influence. Specific humidity is found to have increased in response to rising temperatures, with relative humidity remaining approximately constant. These changes may have important implications, because atmospheric humidity is a key variable in determining the geographical distribution and maximum intensity of precipitation, the potential maximum intensity of tropical cyclones, and human heat stress, and has important effects on the biosphere and surface hydrology.

Wind estimation around the shipwreck of Oriental Star based on field damage surveys and radar observations

OpenAIRE

Meng, Zhiyong; Yao, Dan; Bai, Lanqiang; Zheng, Yongguang; Xue, Ming; Zhang, Xiaoling; Zhao, Kun; Tian, Fuyou; Wang, Mingjun

2016-01-01

Based on observational analyses and on-site ground and aerial damage surveys, this work aims to reveal the weather phenomena?especially the wind situation?when Oriental Star capsized in the Yangtze River on June 1, 2015. Results demonstrate that the cruise ship capsized when it encountered strong winds at speeds of at least 31?m?s?1 near the apex of a bow echo embedded in a squall line. As suggested by the fallen trees within a 2-km radius around the wreck location, such strong winds were lik...

Inelastic damage using continuum damage mechanics in composite plate reinforced by unidirectional fibers

Directory of Open Access Journals (Sweden)

Žmindák Milan

2018-01-01

Full Text Available It is well that a finite element method is very popular simulation method to predict the physical behavior of systems and structures. In the last years an increase of interest in a new type of numerical methods known as meshless methods was observed. The paper deals with application of radial basis functions on modelling of inelastic damage using continuum damage mechanics of layered plate composite structures reinforced with long unidirectional fibers. For numerical simulations of elastic-plastic damage of layered composite plates own computational programs were implemented in MATLAB programming language. We will use the Newton-Raphson method to solve nonlinear systems of equations. Evaluation damage during plasticity has been solved using return mapping algorithm. The results of elastic-plastic damage analysis of composite plate with unsymmetrical laminate stacking sequence are presented.

Dynamic Surface Adaptive Robust Control of Unmanned Marine Vehicles with Disturbance Observer

Directory of Open Access Journals (Sweden)

Pengchao Zhang

2018-01-01

Full Text Available This paper presents a dynamic surface adaptive robust control method with disturbance observer for unmanned marine vehicles (UMV. It uses adaptive law to estimate and compensate the disturbance observer error. Dynamic surface is introduced to solve the “differential explosion” caused by the virtual control derivation in traditional backstepping method. The final controlled system is proved to be globally uniformly bounded based on Lyapunov stability theory. Simulation results illustrate the effectiveness of the proposed controller, which can realize the three-dimensional trajectory tracking for UMV with the systematic uncertainty and time-varying disturbances.

Observations of Building Performance under Combined Wind and Surge Loading from Hurricane Harvey

Science.gov (United States)

Lombardo, F.; Roueche, D. B.; Krupar, R. J.; Smith, D. J.; Soto, M. G.

2017-12-01

Hurricane Harvey struck the Texas coastline on August 25, 2017, as a Category 4 hurricane - the first major hurricane to reach the US in twelve years. Wind gusts over 130 mph and storm surge as high as 12.5 ft caused widespread damage to buildings and critical infrastructure in coastal communities including Rockport, Fulton, Port Aransas and Aransas Pass. This study presents the methodology and preliminary observations of a coordinated response effort to document residential building performance under wind and storm surge loading. Over a twelve day survey period the study team assessed the performance of more than 1,000 individual, geo-located residential buildings. Assessments were logged via a smartphone application to facilitate rapid collection and collation of geotagged photographs, building attributes and structural details, and structural damage observations. Detailed assessments were also made of hazard intensity, specifically storm surge heights and both wind speed and direction indicators. Preliminary observations and findings will be presented, showing strong gradients in damage between inland and coastal regions of the affected areas that may be due in part to enhanced individual loading effects of wind and storm surge and potentially joint-hazard loading effects. Contributing factors to the many cases of disproportionate damage observed in close proximity will also be discussed. Ongoing efforts to relate building damage to near-surface hazard measurements (e.g., radar, anemometry) in close proximity will also be described.

Recent changes in flood damage in the United States from observations and ACME model

Science.gov (United States)

Leng, G.; Leung, L. R.

2017-12-01

Despite efforts to mitigate flood hazards in flood-prone areas, survey- and report-based flood databases show that flood damage has increased and emerged as one of the most costly disaster in the United States since the 1990s. Understanding the mechanism driving the changes in flood damage is therefore critical for reducing flood risk. In this study, we first conduct a comprehensive analysis of the changing characteristics of flood damage at local, state and country level. Results show a significant increasing trend in the number of flood hazards, causing economic losses of up to $7 billion per year. The ratio of flood events that caused tangible economical cost to the total flood events has exhibited a non-significant increasing trend before 2007 followed by a significant decrease, indicating a changing vulnerability to floods. Analysis also reveals distinct spatial and temporal patterns in the threshold intensity of flood hazards with tangible economical cost. To understand the mechanism behind the increasing flood damage, we develop a flood damage economic model coupled with the integrated hydrological modeling system of ACME that features a river routing model with an inundation parameterization and a water use and regulation model. The model is evaluated over the country against historical records. Several numerical experiments are then designed to explore the mechanisms behind the recent changes in flood damage from the perspective of flood hazard, exposure and vulnerability, which constitute flood damage. The role of human activities such as reservoir operations and water use in modifying regional floods are also explored using the new tool, with the goal of improving understanding and modeling of vulnerability to flood hazards.

Mapping Surface Broadband Albedo from Satellite Observations: A Review of Literatures on Algorithms and Products

Directory of Open Access Journals (Sweden)

Ying Qu

2015-01-01

Full Text Available Surface albedo is one of the key controlling geophysical parameters in the surface energy budget studies, and its temporal and spatial variation is closely related to the global climate change and regional weather system due to the albedo feedback mechanism. As an efficient tool for monitoring the surfaces of the Earth, remote sensing is widely used for deriving long-term surface broadband albedo with various geostationary and polar-orbit satellite platforms in recent decades. Moreover, the algorithms for estimating surface broadband albedo from satellite observations, including narrow-to-broadband conversions, bidirectional reflectance distribution function (BRDF angular modeling, direct-estimation algorithm and the algorithms for estimating albedo from geostationary satellite data, are developed and improved. In this paper, we present a comprehensive literature review on algorithms and products for mapping surface broadband albedo with satellite observations and provide a discussion of different algorithms and products in a historical perspective based on citation analysis of the published literature. This paper shows that the observation technologies and accuracy requirement of applications are important, and long-term, global fully-covered (including land, ocean, and sea-ice surfaces, gap-free, surface broadband albedo products with higher spatial and temporal resolution are required for climate change, surface energy budget, and hydrological studies.

Summary of Meteorological Observations, Surface (SMOS), El Toro, California

Science.gov (United States)

1983-10-01

SURFACE WINDS DETACHMENT ASHEVILLE. NC PERCENTAGE FREQUENCY OF WIND DIRECTION AND SPEED (FROM HOURLY OBSERVATIONS) EL TIPO , CALIrQO𔃾IA 73-’.? A ir, U~~tiAL...OF WiND DIRECTION AND SPEED (FROM HOURLY OBSERVATIONS) ... 112L. E L TIPO , ALIODkI1A 71-q2 r ALL wEANCP _______ MEAN 11-11 6.S 7.A 1.U 11.W6 17.21 n...nTa IO STyVIO. *..M YUOnb0U T-mp. WIT BULl TEMPERATUIE DEPRESSION fF) TOTAL TOTAL 0 1- 2 3 -4 - j 8 9 10 11-12113 14,11516117. 18119 270:i21 . 2 23

Microstructural observation of ion-irradiated austenitic stainless steel

International Nuclear Information System (INIS)

Sawai, T.; Hamada, S.; Hishinuma, A.

1992-01-01

Type 316 stainless steel, base metal and weld metal obtained from an electron beam weld joint, was irradiated with 90 MeV Br +6 in the JAERI tandem accelerator. Cross-sectional TEM specimens were obtained by nickel plating. Microstructural observation revealed a band of tiny dislocation loops was observed around the mean projected range and the measured distance from the surface was 6.75±0.15μm. This is slightly larger than the calculated value using Ziegler's stopping power. Defect clusters were also observed around defect sinks within the mean projected range, suggesting cascade-sink interaction. These sinks are the grain boundary in the base metal specimen and preexisting dislocation lines in the weld metal specimen. Surface roughness of polished specimen was detected at the shallower side of the peak damage band, although no visible crystalline defect cluster was observed. This suggests radiation-induced microchemical evolution prior to sever microstructural evolution. (author)

Comparison of land surface humidity between observations and CMIP5 models

Science.gov (United States)

Dunn, Robert J. H.; Willett, Kate M.; Ciavarella, Andrew; Stott, Peter A.

2017-08-01

We compare the latest observational land surface humidity dataset, HadISDH, with the latest generation of climate models extracted from the CMIP5 archive and the ERA-Interim reanalysis over the period 1973 to present. The globally averaged behaviour of HadISDH and ERA-Interim are very similar in both humidity measures and air temperature, on decadal and interannual timescales. The global average relative humidity shows a gradual increase from 1973 to 2000, followed by a steep decline in recent years. The observed specific humidity shows a steady increase in the global average during the early period but in the later period it remains approximately constant. None of the CMIP5 models or experiments capture the observed behaviour of the relative or specific humidity over the entire study period. When using an atmosphere-only model, driven by observed sea surface temperatures and radiative forcing changes, the behaviour of regional average temperature and specific humidity are better captured, but there is little improvement in the relative humidity. Comparing the observed climatologies with those from historical model runs shows that the models are generally cooler everywhere, are drier and less saturated in the tropics and extra-tropics, and have comparable moisture levels but are more saturated in the high latitudes. The spatial pattern of linear trends is relatively similar between the models and HadISDH for temperature and specific humidity, but there are large differences for relative humidity, with less moistening shown in the models over the tropics and very little at high latitudes. The observed drying in mid-latitudes is present at a much lower magnitude in the CMIP5 models. Relationships between temperature and humidity anomalies (T-q and T-rh) show good agreement for specific humidity between models and observations, and between the models themselves, but much poorer for relative humidity. The T-q correlation from the models is more steeply positive than

Venus Surface Composition Constrained by Observation and Experiment

Science.gov (United States)

Gilmore, Martha; Treiman, Allan; Helbert, Jörn; Smrekar, Suzanne

2017-11-01

New observations from the Venus Express spacecraft as well as theoretical and experimental investigation of Venus analogue materials have advanced our understanding of the petrology of Venus melts and the mineralogy of rocks on the surface. The VIRTIS instrument aboard Venus Express provided a map of the southern hemisphere of Venus at ˜1 μm allowing, for the first time, the definition of surface units in terms of their 1 μm emissivity and derived mineralogy. Tessera terrain has lower emissivity than the presumably basaltic plains, consistent with a more silica-rich or felsic mineralogy. Thermodynamic modeling and experimental production of melts with Venera and Vega starting compositions predict derivative melts that range from mafic to felsic. Large volumes of felsic melts require water and may link the formation of tesserae to the presence of a Venus ocean. Low emissivity rocks may also be produced by atmosphere-surface weathering reactions unlike those seen presently. High 1 μm emissivity values correlate to stratigraphically recent flows and have been used with theoretical and experimental predictions of basalt weathering to identify regions of recent volcanism. The timescale of this volcanism is currently constrained by the weathering of magnetite (higher emissivity) in fresh basalts to hematite (lower emissivity) in Venus' oxidizing environment. Recent volcanism is corroborated by transient thermal anomalies identified by the VMC instrument aboard Venus Express. The interpretation of all emissivity data depends critically on understanding the composition of surface materials, kinetics of rock weathering and their measurement under Venus conditions. Extended theoretical studies, continued analysis of earlier spacecraft results, new atmospheric data, and measurements of mineral stability under Venus conditions have improved our understanding atmosphere-surface interactions. The calcite-wollastonite CO2 buffer has been discounted due, among other things, to

Surface composition of Europa based on VLT observations

Science.gov (United States)

Ligier, N.; Poulet, F.; Carter, J.

2016-12-01

Jupiter's moon Europa may harbor a global salty ocean under an 80-170 km thick outer layer consisting of an icy crust (Anderson et al. 1998). Meanwhile, the 10-50 My old surface, dated by cratering rates (Pappalardo et al. 1999) implies rapid surface recycling and reprocessing that could result in tectonic activity (Kattenhorn et al. 2014) and plumes (Roth et al. 2014). The surface could thus exhibit fingerprints of chemical species, as minerals characteristics of an ocean-mantle interaction and/or organics of exobiological interest, directly originating from the subglacial ocean. In order to re-investigate the composition of Europa's surface, a global mapping campaign of the satellite was performed with the near-infrared integral field spectrograph SINFONI on the Very Large Telescope (VLT) in Chile. The high spectral binning of this instrument (0.5 nm) and large signal noise ratio in comparison to previous observations are adequate to detect sharp absorptions in the wavelength range 1.45-2.45 μm. In addition, the spatially resolved spectra we obtained over five epochs nearly cover the entire surface of Europa with a pixel scale of 12.5 by 25 m.a.s ( 35 by 70 km on Europa's surface), thus permitting a global scale study. Several icy and non-icy compounds were detected and mapped at <100 km resolution. They are unevenly distributed on the moon's surface. Amorphous and crystalline water ice are both present and, in spite of a particularly strong amorphization process likely engendered by the Io plasma torus, the crystalline form is found to be approximately twice as abundant as the amorphous ice based on the analysis of the 1.65 μm band. If the surface is dominated by small and mid-sized water ice grains (25-200 μm), crystalline water-ice grains exhibit spatial inhomogeneities in their distribution. The sulfuric acid hydrate distribution exhibits the typical "bullseye" feature on the trailing hemisphere. The presence of Mg-bearing chlorinated salts (chloride

Mechanical properties of ion implanted ceramic surfaces

International Nuclear Information System (INIS)

Burnett, P.J.

1985-01-01

This thesis investigates the mechanisms by which ion implantation can affect those surface mechanical properties of ceramics relevant to their tribological behaviour, specifically hardness and indentation fracture. A range of model materials (including single crystal Si, SiC, A1 2 0 3 , Mg0 and soda-lime-silica glass) have been implanted with a variety of ion species and at a range of ion energies. Significant changes have been found in both low-load microhardness and indentation fracture behaviour. The changes in hardness have been correlated with the evolution of an increasingly damaged and eventually amorphous thin surface layer together with the operation of radiation-, solid-solution- and precipitation-hardening mechanisms. Compressive surface stresses have been shown to be responsible for the observed changes in identation fracture behaviour. In addition, the levels of surface stress present have been correlated with the structure of the surface layer and a simple quantitative model proposed to explain the observed stress-relief upon amorphisation. Finally, the effects of ion implantation upon a range of polycrystalline ceramic materials has been investigated and the observed properties modifications compared and contrasted to those found for the model single crystal materials. (author)

Radiation response of alloy T91 at damage levels up to 1000 peak dpa

Energy Technology Data Exchange (ETDEWEB)

Gigax, J.G., E-mail: gigaxj@tamu.edu [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77840 (United States); Chen, T.; Kim, Hyosim [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77840 (United States); Wang, J. [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77840 (United States); Pacific Northwest National Lab, Richland, WA 99354 (United States); Price, L.M. [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77840 (United States); Aydogan, E. [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77840 (United States); Los Alamos National Lab, Los Alamos, NM 87545 (United States); Maloy, S.A. [Los Alamos National Lab, Los Alamos, NM 87545 (United States); Schreiber, D.K.; Toloczko, M.B. [Pacific Northwest National Lab, Richland, WA 99354 (United States); Garner, F.A. [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77840 (United States); Radiation Effects Consulting, Richland, WA 99354 (United States); Shao, Lin [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77840 (United States)

2016-12-15

Ferritic/martensitic alloys are required for advanced reactor components to survive 500–600 neutron-induced dpa. Ion-induced void swelling of ferritic/martensitic alloy T91 in the quenched and tempered condition has been studied using a defocused, non-rastered 3.5 MeV Fe-ion beam at 475 °C to produce damage levels up to 1000 peak displacements per atom (dpa). The high peak damage level of 1000 dpa is required to reach 500–600 dpa level due to injected interstitial suppression of void nucleation in the peak dpa region, requiring data extraction closer to the surface at lower dpa levels. At a relatively low peak damage level of 250 dpa, voids began to develop, appearing first in the near-surface region. With increasing ion fluence, swelling was observed deeper in the specimen, but remained completely suppressed in the back half of the ion range, even at 1000 peak dpa. The local differences in dpa rate in the front half of the ion range induce an “internal temperature shift” that strongly influences the onset of swelling, with shorter transient regimes resulting from lower dpa rates, in agreement not only with observations in neutron irradiation studies but also in various ion irradiations. Swelling was accompanied by radiation-induced precipitation of Cu-rich and Si, Ni, Mn-rich phases were observed by atom probe tomography, indicating concurrent microchemical evolution was in progress. In comparison to other ferritic/martensitic alloys during ion irradiation, T91 exhibits good swelling resistance with a swelling incubation period of about 400 local dpa.

Damage evolution of TBC system under in-phase thermo-mechanical tests

Energy Technology Data Exchange (ETDEWEB)

Kitazawa, R.; Tanaka, M.; Kagawa, Y. [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Liu, Y.F., E-mail: yfliu@hyper.rcast.u-tokyo.ac.jp [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan)

2010-10-15

In-phase thermo-mechanical tests (TMF) of EB-PVD Y{sub 2}O{sub 3}-ZrO{sub 2} thermal barrier coating (TBC) system (8 wt% Y{sub 2}O{sub 3}-ZrO{sub 2}/CoNiCrAlY/IN-738 substrate) were done under a through-the-thick-direction thermal gradient from TBC surface temperature at 1150 deg. C to substrate temperature at 1000 deg. C. Deformation and failure behaviors of the TBC system were observed at the macroscopic and microscopic scales and damage evolution of the system under in-phase thermo-mechanical test was discussed. Special attention was paid to TBC layer cracking, thermally grown oxide (TGO) layer formation and void formation in bond coat and substrate. Effect of TMF conditions on the damage evolution behaviors was also discussed.

Observational constraints on Arctic boundary-layer clouds, surface moisture and sensible heat fluxes

Science.gov (United States)

Wu, D. L.; Boisvert, L.; Klaus, D.; Dethloff, K.; Ganeshan, M.

2016-12-01

The dry, cold environment and dynamic surface variations make the Arctic a unique but difficult region for observations, especially in the atmospheric boundary layer (ABL). Spaceborne platforms have been the key vantage point to capture basin-scale changes during the recent Arctic warming. Using the AIRS temperature, moisture and surface data, we found that the Arctic surface moisture flux (SMF) had increased by 7% during 2003-2013 (18 W/m2 equivalent in latent heat), mostly in spring and fall near the Arctic coastal seas where large sea ice reduction and sea surface temperature (SST) increase were observed. The increase in Arctic SMF correlated well with the increases in total atmospheric column water vapor and low-level clouds, when compared to CALIPSO cloud observations. It has been challenging for climate models to reliably determine Arctic cloud radiative forcing (CRF). Using the regional climate model HIRHAM5 and assuming a more efficient Bergeron-Findeisen process with generalized subgrid-scale variability for total water content, we were able to produce a cloud distribution that is more consistent with the CloudSat/CALIPSO observations. More importantly, the modified schemes decrease (increase) the cloud water (ice) content in mixed-phase clouds, which help to improve the modeled CRF and energy budget at the surface, because of the dominant role of the liquid water in CRF. Yet, the coupling between Arctic low clouds and the surface is complex and has strong impacts on ABL. Studying GPS/COSMIC radio occultation (RO) refractivity profiles in the Arctic coldest and driest months, we successfully derived ABL inversion height and surface-based inversion (SBI) frequency, and they were anti-correlated over the Arctic Ocean. For the late summer and early fall season, we further analyzed Japanese R/V Mirai ship measurements and found that the open-ocean surface sensible heat flux (SSHF) can explain 10 % of the ABL height variability, whereas mechanisms such as cloud

Observations of Lagrangian transport in the Adriatic Sea from GPS-tracked surface drifters

DEFF Research Database (Denmark)

Carlson, Daniel Frazier

2014-01-01

-dependent dispersion on the surface ocean remains an important open subject in physical oceanography. Lagrangian observations from surface drifters come with their own set of problems, most notably limited numbers, sampling bias, finite lifetime, and position uncertainties from wind and wave effects. Despite...

Localized surface disruptions observed by InSAR during strong earthquakes in Java and Hawai'i

Science.gov (United States)

Poland, M.

2010-01-01

Interferometric Synthetic Aperture Radar data spanning strong earthquakes on the islands of Java and Hawai‘i in 2006 reveal patches of subsidence and incoherence indicative of localized ground failure. Interferograms spanning the 26 May 2006 Java earthquake suggest an area of about 7.5 km2 of subsidence (~2 cm) and incoherence south of the city of Yogyakarta that correlates with significant damage to housing, high modeled peak ground accelerations, and poorly consolidated geologic deposits. The subsidence and incoherence is inferred to be a result of intense shaking and/or damage. At least five subsidence patches on the west side of the Island of Hawai‘i, ranging 0.3–2.2 km2 in area and 3–8 cm in magnitude, occurred as a result of a pair of strong earthquakes on 15 October 2006. Although no felt reports or seismic data are available from the areas in Hawai‘i, the Java example suggests that the subsidence patches indicate areas of amplified earthquake shaking. Surprisingly, all subsidence areas in Hawai‘i were limited to recent, and supposedly stable, lava flows and may reflect geological conditions not detectable at the surface. In addition, two ‘a‘ā lava flows in Hawai‘i were partially incoherent in interferograms spanning the earthquakes, indicating surface disruption as a result of the earthquake shaking. Coearthquake incoherence of rubbly deposits, like ‘a‘ā flows, should be explored as a potential indicator of earthquake intensity and past strong seismic activity.

Applications of high order harmonic radiation to UVX-solids interaction: high excitation density in electronic relaxation dynamics and surface damaging

International Nuclear Information System (INIS)

De Grazia, M.

2007-12-01

The new sources of radiation in the extreme-UV (X-UV: 10-100 nm), which deliver spatially coherent, ultra-short and intense pulses, allow studying high flux processes and ultra-fast dynamics in various domains. The thesis work presents two applications of the high-order laser harmonics (HH) to solid state physics. In Part I, we describe the optimization of the harmonic for studies of X-UV/solids interaction. In Part II, we investigate effects of high excitation density in the dynamics of electron relaxation in dielectric scintillator crystals - tungstates and fluorides, using time-resolved luminescence spectroscopy. Quenching of luminescence at short time gives evidence of the competition between radiative and non-radiative recombination of self-trapped excitons (STE). The non-radiative channel is identified to mutual interaction of STE at high excitation density. In Part III, we study the X-UV induced damage mechanism in various materials, either conductor (amorphous carbon) or insulators (organic polymers, e.g., PMMA). In PMMA-Plexiglas, in the desorption regime (0.2 mJ/cm 2 , i.e., below damage threshold), the surface modifications reflect X-UV induced photochemical processes that are tentatively identified, as a function of dose: at low dose, polymer chain scission followed by the blow-up of the volatile, low-molecular fragments leads to crater formation; at high dose, cross-linking in the near-surface layer of remaining material leads to surface hardening. These promising results have great perspectives considering the performances already attained and planned in the next future in the development of the harmonic sources. (author)

Assimilation of lake water surface temperature observations using an extended Kalman filter

Directory of Open Access Journals (Sweden)

Ekaterina Kourzeneva

2014-10-01

Full Text Available A new extended Kalman filter (EKF-based algorithm to assimilate lake water surface temperature (LWST observations into the lake model/parameterisation scheme Freshwater Lake (FLake has been developed. The data assimilation algorithm has been implemented into the stand-alone offline version of FLake. The mixed and non-mixed regimes in lakes are treated separately by the EKF algorithm. The timing of the ice period is indicated implicitly: no ice if water surface temperature is measured. Numerical experiments are performed using operational in-situ observations for 27 lakes and merged observations (in-situ plus satellite for 4 lakes in Finland. Experiments are analysed, potential problems are discussed, and the role of early spring observations is studied. In general, results of experiments are promising: (1 the impact of observations (calculated as the normalised reduction of the LWST root mean square error comparing to the free model run is more than 90% and (2 in cross-validation (when observations are partly assimilated, partly used for validation the normalised reduction of the LWST error standard deviation is more than 65%. The new data assimilation algorithm will allow prognostic variables in the lake parameterisation scheme to be initialised in operational numerical weather prediction models and the effects of model errors to be corrected by using LWST observations.

WATER SURFACE RECONSTRUCTION IN AIRBORNE LASER BATHYMETRY FROM REDUNDANT BED OBSERVATIONS

Directory of Open Access Journals (Sweden)

G. Mandlburger

2017-09-01

Full Text Available In airborne laser bathymetry knowledge of exact water level heights is a precondition for applying run-time and refraction correction of the raw laser beam travel path in the medium water. However, due to specular reflection especially at very smooth water surfaces often no echoes from the water surface itself are recorded (drop outs. In this paper, we first discuss the feasibility of reconstructing the water surface from redundant observations of the water bottom in theory. Furthermore, we provide a first practical approach for solving this problem, suitable for static and locally planar water surfaces. It minimizes the bottom surface deviations of point clouds from individual flight strips after refraction correction. Both theoretical estimations and practical results confirm the potential of the presented method to reconstruct water level heights in dm precision. Achieving good results requires enough morphological details in the scene and that the water bottom topography is captured from different directions.

Retention and damage in 3C-β SiC irradiated with He and H ions

Energy Technology Data Exchange (ETDEWEB)

Deslandes, Alec, E-mail: alec.deslandes@csiro.au [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales 2232 (Australia); Guenette, Mathew C. [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales 2232 (Australia); Thomsen, Lars [Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168 (Australia); Ionescu, Mihail; Karatchevtseva, Inna; Lumpkin, Gregory R. [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales 2232 (Australia)

2016-02-15

3C-β SiC was implanted with He and H ions using plasma immersion ion implantation (PIII). Regions of damage were created at various depths by applying a sample stage bias of 5 kV, 10 kV, 20 kV or 30 kV. Raman spectroscopy results indicate that He irradiation leads to more damage compared to H irradiation, as observed via increased disordered C and Si signals, as well as broadening of the SiC peaks. X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure spectroscopy (NEXAFS) results indicate significant change to the SiC structure and that surface oxidation has occurred following irradiation, with the degree of change varying dependent on impinging He fluence. The distributions of implanted species were measured using elastic recoil detection analysis. Despite the varying degree and depth of damage created in the SiC by the He ion irradiations, the retained H distribution was observed to not be affected by preceding He implantation.

Observation of low-frequency acoustic surface waves in the nocturnal boundary layer.

Science.gov (United States)

Talmadge, Carrick L; Waxler, Roger; Di, Xiao; Gilbert, Kenneth E; Kulichkov, Sergey

2008-10-01

A natural terrain surface, because of its porosity, can support an acoustic surface wave that is a mechanical analog of the familiar vertically polarized surface wave in AM radio transmission. At frequencies of several hundred hertz, the acoustic surface wave is attenuated over distances of a few hundred meters. At lower frequencies (e.g., below approximately 200 Hz) the attenuation is much less, allowing surface waves to propagate thousands of meters. At night, a low-frequency surface wave is generally present at long ranges even when downward refraction is weak. Thus, surface waves represent a ubiquitous nighttime transmission mode that exists even when other transmission modes are weak or absent. Data from recent nighttime field experiments and theoretical calculations are presented, demonstrating the persistence of the surface wave under different meteorological conditions. The low-frequency surface wave described here is the "quasiharmonical" tail observed previously in nighttime measurements but not identified by S. Kulichkov and his colleagues (Chunchuzov, I. P. et al. 1990. "On acoustical impulse propagation in a moving inhomogeneous atmospheric layer," J. Acoust. Soc. Am. 88, 455-461).

Structural and electrical characterization of HBr/O{sub 2} plasma damage to Si substrate

Energy Technology Data Exchange (ETDEWEB)

Fukasawa, Masanaga; Nakakubo, Yoshinori; Matsuda, Asahiko; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi; Minami, Masaki; Uesawa, Fumikatsu; Tatsumi, Tetsuya [Semiconductor Technology Development Division, Semiconductor Business Group, Professional, Device and Solutions Group, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan); Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Semiconductor Technology Development Division, Semiconductor Business Group, Professional, Device and Solutions Group, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan)

2011-07-15

Silicon substrate damage caused by HBr/O{sub 2} plasma exposure was investigated by spectroscopic ellipsometry (SE), high-resolution Rutherford backscattering spectroscopy, and transmission electron microscopy. The damage caused by H{sub 2}, Ar, and O{sub 2} plasma exposure was also compared to clarify the ion-species dependence. Although the damage basically consists of a surface oxidized layer and underlying dislocated Si, the damage structure strongly depends on the incident ion species, ion energy, and oxidation during air and plasma exposure. In the case of HBr/O{sub 2} plasma exposure, hydrogen generated the deep damaged layer ({approx}10 nm), whereas ion-enhanced diffusion of oxygen, supplied simultaneously by the plasma, caused the thick surface oxidation. In-line monitoring of damage thicknesses by SE, developed with an optimized optical model, showed that the SE can be used to precisely monitor damage thicknesses in mass production. Capacitance-voltage (C-V) characteristics of a damaged layer were studied before and after diluted-HF (DHF) treatment. Results showed that a positive charge is generated at the surface oxide-dislocated Si interface and/or in the bulk oxide after plasma exposure. After DHF treatment, most of the positive charges were removed, while the thickness of the ''Si recess'' was increased by removing the thick surface oxidized layer. As both the Si recess and remaining dislocated Si, including positive charges, cause the degradation of electrical performance, precise monitoring of the surface structure and understanding its effect on device performance is indispensable for creating advanced devices.

Experimental verification of a progressive damage model for composite laminates based on continuum damage mechanics. M.S. Thesis Final Report

Science.gov (United States)

Coats, Timothy William

1994-01-01

Progressive failure is a crucial concern when using laminated composites in structural design. Therefore the ability to model damage and predict the life of laminated composites is vital. The purpose of this research was to experimentally verify the application of the continuum damage model, a progressive failure theory utilizing continuum damage mechanics, to a toughened material system. Damage due to tension-tension fatigue was documented for the IM7/5260 composite laminates. Crack density and delamination surface area were used to calculate matrix cracking and delamination internal state variables, respectively, to predict stiffness loss. A damage dependent finite element code qualitatively predicted trends in transverse matrix cracking, axial splits and local stress-strain distributions for notched quasi-isotropic laminates. The predictions were similar to the experimental data and it was concluded that the continuum damage model provided a good prediction of stiffness loss while qualitatively predicting damage growth in notched laminates.

Surface damage and gas trapping profile measurements in copper during 20 kev He+ irradiation

International Nuclear Information System (INIS)

Terreault, B.; Veilleux, G.

1980-01-01

Surface damage due to 20 keV he + irradiation of OFHC Cu was studied by optical and scanning electron microscopy, and by gas trapping profile measurements with proton backscattering and elastic recoil detection. Both annealed (1 h at 773 K) and unannealed Cu were implanted, at 300 K (0.22Tsub(m)) and 500 K(0.37 Tsub(m)), up to fluences of 3 x 10 18 cm -2 . Additional results with thin (1 μm) evaporated films and stressed cold-rolled foils (3 μm) were obtained. At 500 K in bulk OFHC Cu pores and/or large (approx. 1μm) but scattered blisters appear; at 300 K in bulk or thin film Cu blisters are large and abundant. In all these cases a very large (>=1.5 x 10 1 7 cm -2 ) and sudden release of deeply implanted helium takes place, leading to a depleted profile at a depth of about 90 nm (approx. Rsub(p)). In contrast in cold-rolled foils the blisters are small (approx. 0.4 μm) and the profiles are undepleted. These results are explained by fissuration of helium-pressurized cavities. At high fluence blisters disappear, leaving a porous structure at 500 K and a rough micro-relief at 300 K; the helim profiles are flat and very wide (2-3 Rsub(p)). Blister disappearance, absence of flaking, and porous structure are discussed in terms of the width of the profiles and the formation of a helium-saturated, highly damaged (recrystallized), and permeable layer. (orig.)

Surface layer and bloom dynamics observed with the Prince William Sound Autonomous Profiler

Science.gov (United States)

Campbell, R. W.

2016-02-01

As part of a recent long term monitoring effort, deployments of a WETLabs Autonomous Moored Profiler (AMP) began Prince William Sound (PWS) in 2013. The PWS AMP consists of a positively buoyant instrument frame, with a winch and associated electronics that profiles the frame from a park depth (usually 55 m) to the surface by releasing and retrieving a thin UHMWPE tether; it generally conducts a daily cast and measures temperature, salinity, chlorophyll-a fluorescence, turbidity, and oxygen and nitrate concentrations. Upward and downward looking ADCPs are mounted on a float below the profiler, and an in situ plankton imager is in development and will be installed in 2016. Autonomous profilers are a relatively new technology, and early deployments experienced a number of failures from which valuable lessons may be learned. Nevertheless, an unprecedented time series of the seasonal biogeochemical procession in the surface waters coastal Gulf of Alaska was collected in 2014 and 2015. The northern Gulf of Alaska has experienced a widespread warm anomaly since early 2014, and surface layer temperature anomalies in PWS were strongly positive during winter 2014. The spring bloom observed by the profiler began 2-3 weeks earlier than average, with surface nitrate depleted by late April. Although surface temperatures were still above average in 2015, bloom timing was much later, with a short vigorous bloom in late April and a subsurface bloom in late May that coincided with significant nitrate drawdown. As well as the vernal blooms, wind-driven upwelling events lead to several small productivity pulses that were evident in changes in nitrate and oxygen concentrations, and chlorophyll-a fluorescence. As well as providing a mechanistic understanding of surface layer biogeochemistry, high frequency observations such as these put historical observations in context, and provide new insights into the scales of variability in the annual cycles of the surface ocean in the North

Ion damage calculations in crystalline silicon

International Nuclear Information System (INIS)

Oen, O.S.

1985-07-01

Damage profiles in crystalline silicon produced by light (B) and heavy (Bi) ions with energies from 10 to 100 keV were studied using the computer program MARLOWE (version 12). The program follows not only the incident ion collision by collision, but also any Si target atom that is set into motion through an energetic collision. Thus, the transport effect of the complete cascade of recoiled target atoms is included in the damage profile. The influence of channeling was studied for Si(100) using beam tilt angles from the surface normal of 0 0 , 3 0 and 7 0 about the [001] or [011] axes. The effects of channeling on the damage profile are twofold: first, there is a large reduction of the central damage peak; second, there is a component of the damage profile that extends considerably deeper into the target than that found in conventional studies using a random target assemblage. The influence of amorphous overlayers of SiO 2 on the damage and implantation profiles in the Si(100) substrate has also been investigated

Radiation damage in an amorphous Lennard-Jones solid

International Nuclear Information System (INIS)

Chaki, T.K.; Li, J.C.M.

1985-01-01

A molecular-dynamics simulation of radiation damage in an amorphous Lennard-Jones solid has been undertaken. A three-dimensional structure of 685 atoms with periodic boundary conditions was used. An atom was injected inward from the middle of one surface, and as it lost its energy its velocity and position were recorded. The temperature profile around the injection direction was also calculated. The amorphous structure was examined before and after irradiation by calculating the volume distribution of the Voronoi polyhedra and its time evolution. The production of vacancies and interstitials was observed. The interstitials were found to disappear rapidly, and the vacancies slowly. (author)

Small Optics Laser Damage Test Procedure

Energy Technology Data Exchange (ETDEWEB)

Wolfe, Justin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-10-19

This specification defines the requirements and procedure for laser damage testing of coatings and bare surfaces designated for small optics in the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL).

Detecting Damage in Composite Material Using Nonlinear Elastic Wave Spectroscopy Methods

Science.gov (United States)

Meo, Michele; Polimeno, Umberto; Zumpano, Giuseppe

2008-05-01

Modern aerospace structures make increasing use of fibre reinforced plastic composites, due to their high specific mechanical properties. However, due to their brittleness, low velocity impact can cause delaminations beneath the surface, while the surface may appear to be undamaged upon visual inspection. Such damage is called barely visible impact damage (BVID). Such internal damages lead to significant reduction in local strengths and ultimately could lead to catastrophic failures. It is therefore important to detect and monitor damages in high loaded composite components to receive an early warning for a well timed maintenance of the aircraft. Non-linear ultrasonic spectroscopy methods are promising damage detection and material characterization tools. In this paper, two different non-linear elastic wave spectroscopy (NEWS) methods are presented: single mode nonlinear resonance ultrasound (NRUS) and nonlinear wave modulation technique (NWMS). The NEWS methods were applied to detect delamination damage due to low velocity impact (<12 J) on various composite plates. The results showed that the proposed methodology appear to be highly sensitive to the presence of damage with very promising future NDT and structural health monitoring applications.

Biologically important radiation damage in DNA

International Nuclear Information System (INIS)

Ward, J.F.

1994-01-01

Most DNA damage by the hydroxyl radical is confined to the bases, and this base damage represents an important component of locally multiply demanded sites (LMOS). The yields of the major damaged bases have been determined by gas chromatography mass spectrometry. For our propose, it was necessary to convert a known fraction of these damaged bases to strand breaks and then assay these labile sites as the increase in strand break yield over the normally observed level. Three potential agents by which this strategy of conversion of base damage to strand break could be implemented were identified in the original application: 1, Sl nuclease; 2, piperidine; and 3, base damage specific enzymes

Wavelet Transformation for Damage Identication in Wind Turbine Blades

DEFF Research Database (Denmark)

Ulriksen, Martin Dalgaard; Skov, Jonas falk; Kirkegaard, Poul Henning

2014-01-01

The present paper documents a proposed modal and wavelet analysis-based structural health monitoring (SHM) method for damage identification in wind turbine blades. A finite element (FE) model of a full-scale wind turbine blade is developed and introduced to a transverse surface crack. Hereby, post......-damage mode shapes are derived through modal analysis and subsequently analyzed with continuous two-dimensional wavelet transformation for damage identification, namely detection, localization and assessment. It is found that valid damage identification is obtained even when utilizing the mode shape...

Fine surface structure of unfixed and hydrated macrophages observed by laser-plasma x-ray contact microscopy

International Nuclear Information System (INIS)

Yamamoto, Yoshimasa; Friedman, Herman; Yoshimura, Hideyuki; Kinjo, Yasuhito; Shioda, Seiji; Debari, Kazuhiro; Shinohara, Kunio; Rajyaguru, Jayshree; Richardson, Martin

2000-01-01

A compact, high-resolution, laser-plasma, x-ray contact microscope using a table-top Nd:glass laser system has been developed and utilized for the analysis of the surface structure of live macrophages. Fine fluffy surface structures of murine peritoneal macrophages, which were live, hydrolyzed and not sliced and stained, were observed by the x-ray microscope followed by analysis using an atomic force microscopy. In order to compare with other techniques, a scanning electron microscopy (SEM) was utilized to observe the surface structure of the macrophages. The SEM offered a fine whole cell image of the same macrophages, which were fixed and dehydrated, but the surfaces were ruffled and different from that of x-ray images. A standard light microscope was also utilized to observe the shape of live whole macrophages. Light microscopy showed some fluffy surface structures of the macrophages, but the resolution was too low to observe the fine structures. Thus, the findings of fine fluffy surface structures of macrophages by x-ray microscopy provide valuable information for studies of phagocytosis, cell spreading and adherence, which are dependent on the surface structure of macrophages. Furthermore, the present study also demonstrates the usefulness of x-ray microscopy for analysis of structures of living cells

Damage phenomena at target surface by small leak

International Nuclear Information System (INIS)

Jeong, Kyung Chai; Jeong, J. Y.; Kim, B. H.; Kim, T. J.; Choi, J. H.

2001-04-01

Design of the steam generator should be considered the safety about the sodium-water reaction occurred by water leak in heat transfer tube. Water leak mainly occurred from welding defect at the process of tube connection, the vibration of heat transfer tube bundle in steam generating system, fretting, and pin hole in original tube manufacturing. The classification of water leak divided to two parts, roughly, in case of the water leak studies. One is small leak phenomena analysis, and the other is it of large leak which was mainly treated to the evaluation on pressure increasing from hydrogen gas formed by sodium-water reaction in sodium system. In small water leak, the leak propagation phenomena and the development of leak detecting system at initial stage of small water leak were studied, mainly. In this study, the corrosion phenomena on the target tube surface appeared by sodium-water reaction was analyzed through the small water leak experiments, and, also, the jet phenomena formed by N 2 gas injection through the leak nozzle under water medium was observed

Surface Net Solar Radiation Estimated from Satellite Measurements: Comparisons with Tower Observations

Science.gov (United States)

Li, Zhanqing; Leighton, H. G.; Cess, Robert D.

1993-01-01

A parameterization that relates the reflected solar flux at the top of the atmosphere to the net solar flux at the surface in terms of only the column water vapor amount and the solar zenith angle was tested against surface observations. Net surface fluxes deduced from coincidental collocated satellite-measured radiances and from measurements from towers in Boulder during summer and near Saskatoon in winter have mean differences of about 2 W/sq m, regardless of whether the sky is clear or cloudy. Furthermore, comparisons between the net fluxes deduced from the parameterization and from surface measurements showed equally good agreement when the data were partitioned into morning and afternoon observations. This is in contrast to results from an empirical clear-sky algorithm that is unable to account adequately for the effects of clouds and that shows, at Boulder, a distinct morning to afternoon variation, which is presumably due to the predominance of different cloud types throughout the day. It is also demonstrated that the parameterization may be applied to irradiances at the top of the atmosphere that have been temporally averaged by using the temporally averaged column water vapor amount and the temporally averaged cosine of the solar zenith angle. The good agreement between the results of the parameterization and surface measurements suggests that the algorithm is a useful tool for a variety of climate studies.

Damage analysis. Product improvement through damage analysis; Schadensanalyse. Produktverbesserung durch Schadensanalyse

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-07-01

Within the 37th VDI annual meeting from 19th to 20th May, 2011 in Wuerzburg (Federal Republic of Germany) the following lectures and posters were presented: (1) Malpractice of material processing and heat processing of large gear wheels (P. Sommer); (2) Damages by faulty heat treatment - Case studies: Glow testing at a heat exchanger and wheel breakage of a high-strength screw connection (A. Thomas); (3) Crack formation in pole end plates of high-performance generators of a pumped-storage power plant - Causes and possibilities of remedy (J. Kinder); (4) Grind burn inspection for damage prevention at wind turbine gearboxes - Use of different processes for the investigation of peripheral-zone properties of case-hardened components (T. Griggel); (5) Damage inspection in coal mines using products from the degradation process as an example - damage - inspection - solution: This is the working method of the certification body (C. Kleine-Hegermann); (6) Damages at the sealing rings - Causes of the failure at radial shaft rings (K. Marchetti); (7) Thermal analyses at faulty plastic components (O. Jacobs); (8) Application of the micro computer tomography at damages of fibre-reinforced materials (H. Dinnebier); (9) The significance of 'material defects' from the view of lay people, lawyers and engineers - 'Material defect' in the literature, set of rules and expert opinion (C. Klinger); (10) Material defects from a legal view (P. Henseler); (11) Significance of material defects from the view of an engineering insurer (C. Harden); (12) Wear analyses by means of RNT and non-destructive surface analytics (K. Poehlmann); (13) Damages by means of non-metallic inclusions using ICE 3 as an example - Significance and localisation of single non-metallic inclusions in large components (D. Bettge); (14) Cathodic corrosion protection of pipeline steels (H.-G. Schoeneich); (15) Non-destructive and destructive investigations when assessing damages of corrosion at a

Non-destructive evaluation of UV pulse laser-induced damage performance of fused silica optics.

Science.gov (United States)

Huang, Jin; Wang, Fengrui; Liu, Hongjie; Geng, Feng; Jiang, Xiaodong; Sun, Laixi; Ye, Xin; Li, Qingzhi; Wu, Weidong; Zheng, Wanguo; Sun, Dunlu

2017-11-24

The surface laser damage performance of fused silica optics is related to the distribution of surface defects. In this study, we used chemical etching assisted by ultrasound and magnetorheological finishing to modify defect distribution in a fused silica surface, resulting in fused silica samples with different laser damage performance. Non-destructive test methods such as UV laser-induced fluorescence imaging and photo-thermal deflection were used to characterize the surface defects that contribute to the absorption of UV laser radiation. Our results indicate that the two methods can quantitatively distinguish differences in the distribution of absorptive defects in fused silica samples subjected to different post-processing steps. The percentage of fluorescence defects and the weak absorption coefficient were strongly related to the damage threshold and damage density of fused silica optics, as confirmed by the correlation curves built from statistical analysis of experimental data. The results show that non-destructive evaluation methods such as laser-induced fluorescence and photo-thermal absorption can be effectively applied to estimate the damage performance of fused silica optics at 351 nm pulse laser radiation. This indirect evaluation method is effective for laser damage performance assessment of fused silica optics prior to utilization.

Surface structural damage study in cortical bone due to medical drilling.

Science.gov (United States)

Tavera R, Cesar G; De la Torre-I, Manuel H; Flores-M, Jorge M; Hernandez M, Ma Del Socorro; Mendoza-Santoyo, Fernando; Briones-R, Manuel de J; Sanchez-P, Jorge

2017-05-01

A bone's fracture could be produced by an excessive, repetitive, or sudden load. A regular medical practice to heal it is to fix it in two possible ways: external immobilization, using a ferule, or an internal fixation, using a prosthetic device commonly attached to the bone by means of surgical screws. The bone's volume loss due to this drilling modifies its structure either in the presence or absence of a fracture. To observe the bone's surface behavior caused by the drilling effects, a digital holographic interferometer is used to analyze the displacement surface's variations in nonfractured post-mortem porcine femoral bones. Several nondrilled post-mortem bones are compressed and compared to a set of post-mortem bones with a different number of cortical drillings. During each compression test, a series of digital interferometric holograms were recorded using a high-speed CMOS camera. The results are presented as pseudo 3D mesh displacement maps for comparisons in the physiological range of load (30 and 50 lbs) and beyond (100, 200, and 400 lbs). The high resolution of the optical phase gives a better understanding about the bone's microstructural modifications. Finally, a relationship between compression load and bone volume loss due to the drilling was observed. The results prove that digital holographic interferometry is a viable technique to study the conditions that avoid the surgical screw from loosening in medical procedures of this kind.

A broader classification of damage zones

Science.gov (United States)

Peacock, D. C. P.; Dimmen, V.; Rotevatn, A.; Sanderson, D. J.

2017-09-01

Damage zones have previously been classified in terms of their positions at fault tips, walls or areas of linkage, with the latter being described in terms of sub-parallel and synchronously active faults. We broaden the idea of linkage to include structures around the intersections of non-parallel and/or non-synchronous faults. These interaction damage zones can be divided into approaching damage zones, where the faults kinematically interact but are not physically connected, and intersection damage zones, where the faults either abut or cross-cut. The damage zone concept is applied to other settings in which strain or displacement variations are taken up by a range of structures, such as at fault bends. It is recommended that a prefix can be added to a wide range of damage zones, to describe the locations in which they formed, e.g., approaching, intersection and fault bend damage zone. Such interpretations are commonly based on limited knowledge of the 3D geometries of the structures, such as from exposure surfaces, and there may be spatial variations. For example, approaching faults and related damage seen in outcrop may be intersecting elsewhere on the fault planes. Dilation in intersection damage zones can represent narrow and localised channels for fluid flow, and such dilation can be influenced by post-faulting stress patterns.

Impact of casing damaging on aflatoxin B1 concentration during the ripening of dry-fermented meat sausages.

Science.gov (United States)

Pleadin, Jelka; Kovačević, Dragan; Perković, Irena

2015-01-01

The aim of this article is to investigate the impact of casing damaging on the formation of aflatoxin B1 (AFB1) during the ripening of dry-fermented meat sausages. The level of AFB1 contamination was determined in 24 samples using the ELISA immunoassay throughout a six-month production period. While with intact casing samples no contamination was observed throughout the whole production process, in damaged casing samples AFB1 was detected in the ripening end-stages in the range of 1.62-4.49 μg/kg. The results showed that casing damaging occurring during long-term ripening of dry-fermented sausages can cause AFB1 contamination, possibly arising on the grounds of diffusion of this mycotoxin from the product surface to its interior.

Observations of localised dielectric excitations, secondary events and ionisation damage by scanning transmission electron microscopy

International Nuclear Information System (INIS)

Howie, A.

1988-01-01

In the scanning transmission electron microscope (STEM) a high intensity /approximately/0.5nm diameter, probe of 100 keV electrons is formed. This can be positioned to collect energy loss spectra from surfaces, interfaces, small spheres or other particles at controlled values of impact parameter or can be scanned across the object (usually a thin film) to produce high resolution images formed from a variety of signals - small angle or large angle (Z contrast) elastic scattering, inelastic scattering (both valence and core losses), secondary electron emission and x-ray or optical photon emission. The high spatial resolution achievable in a variety of simple structures raises many unsolved theoretical problems concerning the generation, propagation and decay of excitations in inhomogeneous media. These range from quite well posed problems in the mathematical physics of dielectric excitation to problems of plasmon propagation and rather more exotic and less well understood problems of radiation damage. 15 refs., 4 figs

Damage characterization for particles filled semi-crystalline polymer

Directory of Open Access Journals (Sweden)

Lauro Franck

2015-01-01

Full Text Available Damage evolution and characterization in semi-crystalline polymer filled with particles under various loadings is still a challenge. A specific damage characterization method using Digital Image Correlation is proposed for a wide range of strain rates considering tensile tests with hydraulic jacks as well as Hopkinson's bars. This damage measurement is obtained by using and adapting the SEE method [1] which was developed to characterize the behaviour laws at constant strain rates of polymeric materials in dynamic. To validate the characterization process, various damage measurement techniques are used under quasi-static conditions before to apply the procedure in dynamic. So, the well-known damage characterization by loss of stiffness technique under quasi-static loading is applied to a polypropylene. In addition, an in-situ tensile test, carried out in a microtomograph, is used to observe the cavitation phenomenon in real time. A good correlation is obtained between all these techniques and consequently the proposed technique is supposed suitable for measuring the ductile damage observed in semi-crystalline polymers under dynamic loading. By applying it to the semi-crystalline polymer at moderate and high speed loadings, the damage evolution is measured and it is observed that the damage evolution is not strain rate dependent but the failure strain on the contrary is strain rate dependent.

Impact of dielectric parameters on the reflectivity of 3C–SiC wafers with a rough surface morphology in the reststrahlen region

International Nuclear Information System (INIS)

Engelbrecht, J.A.A.; Janzén, E.; Henry, A.; Rooyen, I.J. van

2014-01-01

A layer-on-substrate model is used to obtain the infrared reflectance for 3C–SiC with a rough surface morphology. The effect of varying dielectric parameters of the “damaged layer” on the observed reflectivity of the 3C–SiC in the reststrahlen region is assessed. Different simulated reflectance spectra are obtained to those if the dielectric parameters of the “substrate” were varied. Most notable changes in the shape of the simulated reststrahlen peak are observed for changes in the high frequency dielectric constant, the phonon damping constant, the phonon frequencies and “thickness” of damaged surface layer.

Impact of dielectric parameters on the reflectivity of 3C–SiC wafers with a rough surface morphology in the reststrahlen region

Energy Technology Data Exchange (ETDEWEB)

Engelbrecht, J.A.A., E-mail: Japie.Engelbrecht@nmmu.ac.za [Physics Department, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Janzén, E.; Henry, A. [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Rooyen, I.J. van [Fuel Performance and Design Department, Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415-6188 (United States)

2014-04-15

A layer-on-substrate model is used to obtain the infrared reflectance for 3C–SiC with a rough surface morphology. The effect of varying dielectric parameters of the “damaged layer” on the observed reflectivity of the 3C–SiC in the reststrahlen region is assessed. Different simulated reflectance spectra are obtained to those if the dielectric parameters of the “substrate” were varied. Most notable changes in the shape of the simulated reststrahlen peak are observed for changes in the high frequency dielectric constant, the phonon damping constant, the phonon frequencies and “thickness” of damaged surface layer.

Study of surface activation of PET by low energy (keV) Ni+ and N+ ion implantation

International Nuclear Information System (INIS)

Nathawat, Rashi; Kumar, Anil; Kulshrestha, V.; Vijay, Y.K.; Kobayashi, T.; Kanjilal, D.

2008-01-01

Polyethyleneterephthalate (PET) has been modified by 100 keV Ni + and N + ions using metal ion from volatile compound (MIVOC) ion source to fluence ranging from 1 x 10 14 to 1 x 10 16 ions/cm 2 . The increasing application of polymeric material in technological and scientific field has motivated the use of surface treatment to modify the physical and chemical properties of polymer surfaces. When a material is exposed to ionization radiation, it suffers damage leading to surface activation depending on the type. The surface morphology was observed by atomic force microscopy (AFM). That show the roughness increases with fluence in both the cases. The Ni particles as precipitation in PET were observed by cross-section transmission electron microscopy (XTEM). The optical band gap (E g ) deduced from absorption spectra; was calculated by Tau'c relation. Raman spectroscopy shows quantitatively the chemical nature at the damage caused by the Ni + and N + bombardment. The ration of I D /I G shows graphite-like structure is formed on the surface. A layer of hydrogenated amorphous carbon is formed on the surface, which has confirmed by XPS results also.

Effect of stacking angles on mechanical properties and damage propagation of plain woven carbon fiber laminates

Science.gov (United States)

Zhuang, Weimin; Ao, Wenhong

2018-03-01

Damage propagation induced failure is a predominant damage mechanism. This study is aimed at assessing the damage state and damage propagation induced failure with different stacking angles, of woven carbon fiber/epoxy laminates subjected to quasi-static tensile and bending load. Different stages of damage processing and damage behavior under the bending load are investigated by Scanning Electron Microscopy (SEM). The woven carbon fiber/epoxy laminates which are stacked at six different angles (0°, 15°, 30°, 45°, 60°, 75°) with eight plies have been analyzed: [0]8, [15]8, [30]8, [45]8, [60]8, [75]8. Three-point bending test and quasi-static tensile test are used in validating the woven carbon fiber/epoxy laminates’ mechanical properties. Furthermore, the damage propagation and failure modes observed under flexural loading is correlated with flexural force and load-displacement behaviour respectively for the laminates. The experimental results have indicated that [45]8 laminate exhibits the best flexural performance in terms of energy absorption duo to its pseudo-ductile behaviour but the tensile strength and flexural strength drastically decreased compared to [0]8 laminate. Finally, SEM micrographs of specimens and fracture surfaces are used to reveal the different types of damage of the laminates with different stacking angles.

Scratch resistance and localised damage characteristics of polymer surfaces - a review

Energy Technology Data Exchange (ETDEWEB)

Briscoe, B.J. [Department of Chemical Engineering and Chemical Technology, Imperial College, London SW7 2BY (United Kingdom); Sinha, S.K. [Department of Mechanical Engineering, National University of Singapore (Singapore)

2003-11-01

The ''Scratch Test'' is, arguably, the earliest and amongst the now most widely used techniques for evaluating a wide range of surface mechanical properties. Some of the areas where this test has been successfully used in the engineering field, both by research and industry, include the determination of the relative hardness of materials, characterizations of coatings, paints and thin-films, modeling of the wear of materials and the estimation of different material deformation characteristics when subjected to hard asperity damage. In this paper we have reviewed the ''state-of-the-art'' in the scratch method for polymeric materials. The paper provides some important theoretical models that have been developed in the field of scratching for material property characterizations. Results from different types of scratch tests (macro, micro and nano scales) on a range of polymeric materials are presented with critical discussion on the usefulness of each result. Finally, various areas for further research in scratching of polymer surfaces have been identified. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Der ''Ritztest'' ist wohl das aelteste und mit am meisten verwendete Verfahren zur Beurteilung von oberflaechenmechanischen Eigenschaften. Zu den technischen Bereichen, in denen dieser Test sowohl in der Forschung als auch in der Industrie erfolgreich Anwendung gefunden hat, zaehlen die Bestimmung der relativen Materialhaerte, die Charakterisierung von Beschichtungen, Lackierungen und Duennschichten, die Modellierung des Werkstoffverschleisses sowie die Abschaetzung verschiedener Werkstoffverformungsparameter bei Beanspruchung durch harte Rauheitsspitzen. Der vorliegende Bericht beschreibt den gegenwaertigen Stand der Anwendung des Ritzverfahrens fuer polymere Materialien. Er enthaelt wichtige theoretische Modelle, die fuer die Anwendung des Ritzens zur Charakterisierung von

Microstructure and damage behavior of W-Cr alloy under He irradiation

Science.gov (United States)

Huang, Ke; Luo, Lai-Ma; Zan, Xiang; Xu, Qiu; Liu, Dong-Guang; Zhu, Xiao-Yong; Cheng, Ji-Gui; Wu, Yu-Cheng

2018-04-01

In this study, a large-power inductively coupled plasma source was designed to perform the continuous helium ion irradiations of W-Cr binary alloy (W-20 wt%Cr) under relevant conditions of the International Thermonuclear Experimental Reactor. Surface damages and microstructures of irradiated W-20Cr were observed by using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. The addition of Cr dramatically enhanced the micro-hardness of the obtained bulk materials, and the interface between the W matrix and the second phase Cr-O is a semi-coherent interface. After irradiation, the doping of Cr element effectively reduces the damage of the W matrix during the irradiation process. The semi-coherent interface between the second phase and the W matrix improves the anti-irradiation performance of the W-20Cr alloy.

Impact of satellite-based lake surface observations on the initial state of HIRLAM. Part II: Analysis of lake surface temperature and ice cover

Directory of Open Access Journals (Sweden)

Homa Kheyrollah Pour

2014-09-01

Full Text Available This paper presents results from a study on the impact of remote-sensing Lake Surface Water Temperature (LSWT observations in the analysis of lake surface state of a numerical weather prediction (NWP model. Data assimilation experiments were performed with the High Resolution Limited Area Model (HIRLAM, a three-dimensional operational NWP model. Selected thermal remote-sensing LSWT observations provided by the Moderate Resolution Imaging Spectroradiometer (MODIS and Advanced Along-Track Scanning Radiometer (AATSR sensors onboard the Terra/Aqua and ENVISAT satellites, respectively, were included into the assimilation. The domain of our experiments, which focussed on two winters (2010–2011 and 2011–2012, covered northern Europe. Validation of the resulting objective analyses against independent observations demonstrated that the description of the lake surface state can be improved by the introduction of space-borne LSWT observations, compared to the result of pure prognostic parameterisations or assimilation of the available limited number of in-situ lake temperature observations. Further development of the data assimilation methods and solving of several practical issues are necessary in order to fully benefit from the space-borne observations of lake surface state for the improvement of the operational weather forecast. This paper is the second part of a series of two papers aimed at improving the objective analysis of lake temperature and ice conditions in HIRLAM.

Automatic Detection of Storm Damages Using High-Altitude Photogrammetric Imaging

Science.gov (United States)

Litkey, P.; Nurminen, K.; Honkavaara, E.

2013-05-01

The risks of storms that cause damage in forests are increasing due to climate change. Quickly detecting fallen trees, assessing the amount of fallen trees and efficiently collecting them are of great importance for economic and environmental reasons. Visually detecting and delineating storm damage is a laborious and error-prone process; thus, it is important to develop cost-efficient and highly automated methods. Objective of our research project is to investigate and develop a reliable and efficient method for automatic storm damage detection, which is based on airborne imagery that is collected after a storm. The requirements for the method are the before-storm and after-storm surface models. A difference surface is calculated using two DSMs and the locations where significant changes have appeared are automatically detected. In our previous research we used four-year old airborne laser scanning surface model as the before-storm surface. The after-storm DSM was provided from the photogrammetric images using the Next Generation Automatic Terrain Extraction (NGATE) algorithm of Socet Set software. We obtained 100% accuracy in detection of major storm damages. In this investigation we will further evaluate the sensitivity of the storm-damage detection process. We will investigate the potential of national airborne photography, that is collected at no-leaf season, to automatically produce a before-storm DSM using image matching. We will also compare impact of the terrain extraction algorithm to the results. Our results will also promote the potential of national open source data sets in the management of natural disasters.

Surface analyses of TiC coated molybdenum limiter material exposed to high heat flux electron beam

International Nuclear Information System (INIS)

Onozuka, M.; Uchikawa, T.; Yamao, H.; Kawai, H.; Kousaku, A.; Nakamura, H.; Niikura, S.

1987-01-01

Observation and surface analyses of TiC coated molybdenum exposed to high heat flux have been performed to study thermal damage resistance of TiC coated molybdenum limiter material. High heat loads were provided by a 120 kW electron beam facility. SEM, AES and EPMA have been applied to the surface analyses

Tree-based flood damage modeling of companies: Damage processes and model performance

Science.gov (United States)

Sieg, Tobias; Vogel, Kristin; Merz, Bruno; Kreibich, Heidi

2017-07-01

Reliable flood risk analyses, including the estimation of damage, are an important prerequisite for efficient risk management. However, not much is known about flood damage processes affecting companies. Thus, we conduct a flood damage assessment of companies in Germany with regard to two aspects. First, we identify relevant damage-influencing variables. Second, we assess the prediction performance of the developed damage models with respect to the gain by using an increasing amount of training data and a sector-specific evaluation of the data. Random forests are trained with data from two postevent surveys after flood events occurring in the years 2002 and 2013. For a sector-specific consideration, the data set is split into four subsets corresponding to the manufacturing, commercial, financial, and service sectors. Further, separate models are derived for three different company assets: buildings, equipment, and goods and stock. Calculated variable importance values reveal different variable sets relevant for the damage estimation, indicating significant differences in the damage process for various company sectors and assets. With an increasing number of data used to build the models, prediction errors decrease. Yet the effect is rather small and seems to saturate for a data set size of several hundred observations. In contrast, the prediction improvement achieved by a sector-specific consideration is more distinct, especially for damage to equipment and goods and stock. Consequently, sector-specific data acquisition and a consideration of sector-specific company characteristics in future flood damage assessments is expected to improve the model performance more than a mere increase in data.

Near-surface bulk densities of asteroids derived from dual-polarization radar observations

Science.gov (United States)

Virkki, A.; Taylor, P. A.; Zambrano-Marin, L. F.; Howell, E. S.; Nolan, M. C.; Lejoly, C.; Rivera-Valentin, E. G.; Aponte, B. A.

2017-09-01

We present a new method to constrain the near-surface bulk density and surface roughness of regolith on asteroid surfaces using planetary radar measurements. The number of radar observations has increased rapidly during the last five years, allowing us to compare and contrast the radar scattering properties of different small-body populations and compositional types. This provides us with new opportunities to investigate their near-surface physical properties such as the chemical composition, bulk density, porosity, or the structural roughness in the scale of centimeters to meters. Because the radar signal can penetrate into a planetary surface up to a few decimeters, radar can reveal information that is hidden from other ground-based methods, such as optical and infrared measurements. The near-surface structure of asteroids and comets in centimeter-to-meter scale is essential information for robotic and human space missions, impact threat mitigation, and understanding the history of these bodies as well as the formation of the whole Solar System.

Regrowth zones in laser annealed radiation damaged diamond

International Nuclear Information System (INIS)

Jamieson, D.N.; Prawer, S.; Dooley, S.P.; Kalish, R.; Technion-Israel Inst. of Tech., Haifa

1993-01-01

Focused laser annealing of ion implanted diamond with a 15 μm diameter laser spot produces as variety of effects that depend on the power density of the laser. Channeling Contrast Microscopy (CCM) provides a relatively straight forward, rapid, method to analyse the annealed regions of the diamond to characterize the effects. In order of increasing laser power density, effects that are observed include: regrowth of the end of range damage of the ion implantation, formation of a buried graphitic layer and complete graphitization of the surface of the diamond down to the bottom of the original damage layer. Information provided by CCM leads to an understanding the causes of these effects and provides insight into the carbon phase diagram in the neighbourhood of the graphite to diamond phase transition. Analysis of the effects of laser annealing by CCM are complicated by the swelling of the diamond lattice caused by the original ion implantation, compaction following regrowth and the effect of the analysis beam irradiation itself. 12 refs., 5 figs

Creep damage in zircaloy-4 at LWR temperatures

International Nuclear Information System (INIS)

Keusseyan, R.L.; Hu, C.P.; Li, C.Y.

1978-08-01

The observation of creep damage in the form of grain boundary cavitation in Zircaloy-4 in the temperature range of interest to Light Water Reactor (LWR) applications is reported. The observed damage is shown to reduce the ductility of Zircaloy-4 in a tensile test at LWR temperatures

Detection of Damage in Operating Wind Turbines by Signature Distances

Directory of Open Access Journals (Sweden)

James F. Manwell

2013-01-01

Full Text Available Wind turbines operate in the atmospheric boundary layer and are subject to complex random loading. This precludes using a deterministic response of healthy turbines as the baseline for identifying the effect of damage on the measured response of operating turbines. In the absence of such a deterministic response, the stochastic dynamic response of the tower to a shutdown maneuver is found to be affected distinctively by damage in contrast to wind. Such a dynamic response, however, cannot be established for the blades. As an alternative, the estimate of blade damage is sought through its effect on the third or fourth modal frequency, each found to be mostly unaffected by wind. To discern the effect of damage from the wind effect on these responses, a unified method of damage detection is introduced that accommodates different responses. In this method, the dynamic responses are transformed to surfaces via continuous wavelet transforms to accentuate the effect of wind or damage on the dynamic response. Regions of significant deviations between these surfaces are then isolated in their corresponding planes to capture the change signatures. The image distances between these change signatures are shown to produce consistent estimates of damage for both the tower and the blades in presence of varying wind field profiles.

Automatic detection and classification of damage zone(s) for incorporating in digital image correlation technique

Science.gov (United States)

Bhattacharjee, Sudipta; Deb, Debasis

2016-07-01

Digital image correlation (DIC) is a technique developed for monitoring surface deformation/displacement of an object under loading conditions. This method is further refined to make it capable of handling discontinuities on the surface of the sample. A damage zone is referred to a surface area fractured and opened in due course of loading. In this study, an algorithm is presented to automatically detect multiple damage zones in deformed image. The algorithm identifies the pixels located inside these zones and eliminate them from FEM-DIC processes. The proposed algorithm is successfully implemented on several damaged samples to estimate displacement fields of an object under loading conditions. This study shows that displacement fields represent the damage conditions reasonably well as compared to regular FEM-DIC technique without considering the damage zones.

An Improved Method of Mitigating Laser Induced Surface Damage Growth in Fused Silica Using a Rastered, Pulsed CO2 Laser

Energy Technology Data Exchange (ETDEWEB)

Bass, I L; Guss, G M; Nostrand, M J; Wegner, P L

2010-10-21

A new method of mitigating (arresting) the growth of large (>200 m diameter and depth) laser induced surface damage on fused silica has been developed that successfully addresses several issues encountered with our previously-reported large site mitigation technique. As in the previous work, a tightly-focused 10.6 {micro}m CO{sub 2} laser spot is scanned over the damage site by galvanometer steering mirrors. In contrast to the previous work, the laser is pulsed instead of CW, with the pulse length and repetition frequency chosen to allow substantial cooling between pulses. This cooling has the important effect of reducing the heat-affected zone capable of supporting thermo-capillary flow from scale lengths on the order of the overall scan pattern to scale lengths on the order of the focused laser spot, thus preventing the formation of a raised rim around the final mitigation site and its consequent down-stream intensification. Other advantages of the new method include lower residual stresses, and improved damage threshold associated with reduced amounts of redeposited material. The raster patterns can be designed to produce specific shapes of the mitigation pit including cones and pyramids. Details of the new technique and its comparison with the previous technique will be presented.

Wind estimation around the shipwreck of Oriental Star based on field damage surveys and radar observations.

Science.gov (United States)

Meng, Zhiyong; Yao, Dan; Bai, Lanqiang; Zheng, Yongguang; Xue, Ming; Zhang, Xiaoling; Zhao, Kun; Tian, Fuyou; Wang, Mingjun

Based on observational analyses and on-site ground and aerial damage surveys, this work aims to reveal the weather phenomena-especially the wind situation-when Oriental Star capsized in the Yangtze River on June 1, 2015. Results demonstrate that the cruise ship capsized when it encountered strong winds at speeds of at least 31 m s -1 near the apex of a bow echo embedded in a squall line. As suggested by the fallen trees within a 2-km radius around the wreck location, such strong winds were likely caused by microburst straight-line wind and/or embedded small vortices, rather than tornadoes.

Cluster-surface collisions: Characteristics of Xe55- and C20 - Si[111] surface bombardment

International Nuclear Information System (INIS)

Cheng, H.

1999-01-01

Molecular dynamics (MD) simulations are performed to study the cluster-surface collision processes. Two types of clusters, Xe 55 and C 20 are used as case studies of materials with very different properties. In studies of Xe 55 - Si[111] surface bombardment, two initial velocities, 5.0 and 10.0 km/s (normal to the surface) are chosen to investigate the dynamical consequences of the initial energy or velocity in the cluster-surface impact. A transition in the speed of kinetic energy propagation, from subsonic velocities to supersonic velocities, is observed. Energy transfer, from cluster translational motion to the substrate, occurs at an extremely fast rate that increases as the incident velocity increases. Local melting and amorphous layer formation in the surfaces are found via energetic analysis of individual silicon atoms. For C 20 , the initial velocity ranges from 10 to 100 km/s. The clusters are damaged immediately upon impact. Similar to Xe 55 , increase in the potential energy is larger than the increase in internal kinetic energy. However, the patterns of energy distribution are different for the two types of clusters. The energy transfer from the carbon clusters to Si(111) surface is found to be slower than that found in the Xe clusters. Fragmentation of the carbon cluster occurs when the initial velocity is greater than 30 km/s. At 10 km/s, the clusters show recrystallization at later times. The average penetration depth displays a nonlinear dependence on the initial velocity. Disturbance in the surface caused by C 20 is discussed and compared to the damage caused by Xe 55 . Energetics, structures, and dynamics of these systems are fully analyzed and characterized. copyright 1999 American Institute of Physics

Characteristics of Asperity Damage and Its Influence on the Shear Behavior of Granite Joints

Science.gov (United States)

Meng, Fanzhen; Zhou, Hui; Wang, Zaiquan; Zhang, Chuanqing; Li, Shaojun; Zhang, Liming; Kong, Liang

2018-02-01

Surface roughness significantly affects the shear behavior of rock joints; thus, studies on the asperity damage characteristics and its influence on the shear behavior of joints are extremely important. In this paper, shear tests were conducted on tensile granite joints; asperity damage was evaluated based on acoustic emission (AE) events; and the influence of asperity damage on joint shear behavior was analyzed. The results indicated that the total AE events tended to increase with normal stress. In addition, the asperity damage initiation shear stress, which is defined as the transition point from slow growth to rapid growth in the cumulative events curve, was approximately 0.485 of the peak shear strength regardless of the normal stress. Moreover, 63-85% of the AE events were generated after the peak shear stress, indicating that most of the damage occurred in this stage. Both the dilation and the total AE events decreased with shear cycles because of the damage inflicted on asperities during the previous shear cycle. Two stages were observed in the normal displacement curves under low normal stress, whereas three stages (compression, dilation and compression again) were observed at a higher normal stress; the second compression stage may be caused by tensile failure outside the shear plane. The magnitude of the normal stress and the state of asperity are two important factors controlling the post-peak stress drop and stick-slip of granite joints. Serious deterioration of asperities will stop stick-slip from recurring under the same normal stress because the ability to accumulate energy is decreased. The AE b-value increases with the number of shear cycles, indicating that the stress concentration inside the fault plane is reduced because of asperity damage; thus, the potential for dynamic disasters, such as fault-slip rockbursts, will be decreased.

Kinetics of Accumulation of Damage in Surface Layers of Lithium-Containing Aluminum Alloys in Fatigue Tests with Rigid Loading Cycle and Corrosive Effect of Environment

Science.gov (United States)

Morozova, L. V.; Zhegina, I. P.; Grigorenko, V. B.; Fomina, M. A.

2017-07-01

High-resolution methods of metal physics research including electron, laser and optical microscopy are used to study the kinetics of the accumulation of slip lines and bands and the corrosion damage in the plastic zone of specimens of aluminum-lithium alloys 1441 and B-1469 in rigid-cycle fatigue tests under the joint action of applied stresses and corrosive environment. The strain parameters (the density of slip bands, the sizes of plastic zones near fracture, the surface roughness in singled-out zones) and the damage parameters (the sizes of pits and the pitting area) are evaluated.

Developments, characterization and proton irradiation damage tests of AlN detectors for VUV solar observations

Energy Technology Data Exchange (ETDEWEB)

BenMoussa, A., E-mail: ali.benmoussa@stce.be [Solar Terrestrial Center of Excellence (STCE), Royal Observatory of Belgium, Circular Avenue 3, B-1180 Brussels (Belgium); Soltani, A.; Gerbedoen, J.-C [Institut d’Electronique, de Microélectronique et de Nanotechnologie (IEMN), F-59652 Villeneuve d’Ascq (France); Saito, T. [Department of Environment and Energy, Tohoku Institute of Technology, 35-1, Yagiyama-Kasumi-cho, Taihaku-ku, Sendai, Miyagi 982-8577 (Japan); Averin, S. [Fryazino Branch of the Kotel’nikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, 141190 Square Vvedenski 1, Fryazino, Moscow Region (Russian Federation); Gissot, S.; Giordanengo, B. [Solar Terrestrial Center of Excellence (STCE), Royal Observatory of Belgium, Circular Avenue 3, B-1180 Brussels (Belgium); Berger, G. [Catholic University of Louvain-la-Neuve, Chemin du Cyclotron 2, B-1348 Louvain la Neuve (Belgium); Kroth, U. [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, D-10587 Berlin (Germany); De Jaeger, J.-C. [Institut d’Electronique, de Microélectronique et de Nanotechnologie (IEMN), F-59652 Villeneuve d’Ascq (France); Gottwald, A. [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, D-10587 Berlin (Germany)

2013-10-01

For next generation spaceborne solar ultraviolet radiometers, innovative metal–semiconductor–metal detectors based on wurtzite aluminum nitride are being developed and characterized. A set of measurement campaigns and proton irradiation damage tests was carried out to obtain their ultraviolet-to-visible characterization and degradation mechanisms. First results on large area prototypes up to 4.3 mm diameter are presented here. In the wavelength range of interest, this detector is reasonably sensitive and stable under brief irradiation with a negligible low dark current (3–6 pA/cm{sup 2}). No significant degradation of the detector performance was observed after exposure to protons of 14.4 MeV energy, showing a good radiation tolerance up to fluences of 1 × 10{sup 11} protons/cm{sup 2}.

Boundary layer transition observations on a body of revolution with surface heating and cooling in water

Science.gov (United States)

Arakeri, V. H.

1980-04-01

Boundary layer flow visualization in water with surface heat transfer was carried out on a body of revolution which had the predicted possibility of laminar separation under isothermal conditions. Flow visualization was by in-line holographic technique. Boundary layer stabilization, including elimination of laminar separation, was observed to take place on surface heating. Conversely, boundary layer destabilization was observed on surface cooling. These findings are consistent with the theoretical predictions of Wazzan et al. (1970).

Damage caused by a nanosecond UV laser on a heated copper surface

Energy Technology Data Exchange (ETDEWEB)

Henč-Bartolić, V., E-mail: visnja.henc@fer.hr [University of Zagreb, Faculty of Electrical Engineering and Computing, Unska 3, 10000 Zagreb (Croatia); Bončina, T. [University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor (Slovenia); Jakovljević, S., E-mail: suzana.jakovljevic@fsb.hr [University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Ivana Lučića 5, 10002 Zagreb (Croatia); Panjan, P. [Jožef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Zupanič, F. [University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor (Slovenia)

2016-08-15

Highlights: • A Cu-plate was exposed to nanosecond UV laser with max. energy 1.1 J/cm{sup 2}. • Surface topography was studied on the cold and heated copper plate. • At room temperature, a crater formed, the melt was ejected from it. • Capillary waves formed in the vicinity of the crater at 360 °C. - Abstract: This work studied the effect of thin copper plate temperature on its surface morphology after irradiation using a pulsed nanosecond UV laser. The surface characteristics were investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, focused ion beam and stylus profilometry. When a target was at room temperature, a crater and the radial flow of molten Cu from the crater was observed. When the thin target was warm (about 360 °C ± 20 °C), a crater was smaller, and quasi-semicircular waves with the periodicity of around 3 μm appeared in its vicinity. The origin of the waves is Marangoni effect, causing thermocapillary waves, which in same occasions had a structure of final states of chaos in Rayleigh–Bénard convection.

A New Experimental Approach to Evaluate Plasma-induced Damage in Microcantilever

Directory of Open Access Journals (Sweden)

Yuki Nishimori

2013-09-01

Full Text Available Plasma  etching,  during  micro-fabrication  processing  is  indispensable  for  fabricating  MEMS  structures.  During  the plasma  processes,  two  major matters,  charged  ions  and  vacuum–ultraviolet  (VUV  irradiation  damage,  take  charge  of reliability  degradation.  The  charged  ions  induce  unwanted  sidewall  etching,  generally  called  as  “notching”,  which causes  degradation  in  brittle  strength.  Furthermore,  the  VUV  irradiation  gives  rise  to  crystal  defects  on  the  etching surface.  To overcome  the  problem,  neutral  beam  etching  (NBE,  which  use  neutral  particles  without  the  VUV irradiation,  has  been  developed.  In  order  to  evaluate  the  effect  of  the  NBE  quantitatively,  we  measured  the  resonance property of a micro-cantilever before and after NBE treatment. The thickness of damage layer (δ times the imaginary part  of  the  complex Young's  modulus  (Eds  were  then  compared,  which  is  a  parameter  of  surface  damage.  Although plasma processes  make the initial surface of cantilevers damaged during their fabrication, the removal of that damage by NBE was confirmed as the reduction in δEds. NBE will realize a damage-free surface for microstructures.

Damage assessment using advanced non-intrusive inspection methods: integration of space, UAV, GPR, and field spectroscopy

Science.gov (United States)

Themistocleous, Kyriacos; Neocleous, Kyriacos; Pilakoutas, Kypros; Hadjimitsis, Diofantos G.

2014-08-01

The predominant approach for conducting road condition surveys and analyses is still largely based on extensive field observations. However, visual assessment alone cannot identify the actual extent and severity of damage. New non-invasive and cost-effective non-destructive (NDT) remote sensing technologies can be used to monitor road pavements across their life cycle, including remotely sensed aerial and satellite visual and thermal image (AI) data, Unmanned Aerial Vehicles (UAVs), Spectroscopy and Ground Penetrating Radar (GRP). These non-contact techniques can be used to obtain surface and sub-surface information about damage in road pavements, including the crack depth, and in-depth structural failure. Thus, a smart and cost-effective methodology is required that integrates several of these non-destructive/ no-contact techniques for the damage assessment and monitoring at different levels. This paper presents an overview of how an integration of the above technologies can be used to conduct detailed road condition surveys. The proposed approach can also be used to predict the future needs for road maintenance; this information is proven to be valuable to a strategic decision making tools that optimizes maintenance based on resources and environmental issues.

Application of RMS for damage detection by guided elastic waves

Energy Technology Data Exchange (ETDEWEB)

Radzienski, M; Dolinski, L; Krawczuk, M [Gdansk University of Technology, Faculty of Electrical and Control Engineering, Narutowicza 11/12, 80-952 Gdansk (Poland); Zak, A; Ostachowicz, W, E-mail: Maciej.Radzienski@gmail.com [Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-952 Gdansk (Poland)

2011-07-19

This paper presents certain results of an experimental study related with a damage detection in structural elements based on deviations in guided elastic wave propagation patterns. In order to excite guided elastic waves within specimens tested piezoelectric transducers have been applied. As excitation signals 5 sine cycles modulated by Hanning window have been used. Propagation of guided elastic waves has been monitored by a scanning Doppler laser vibrometer. The time signals recorded during measurement have been utilised to calculate the values of RMS. It has turned out that the values of RMS differed significantly in damaged areas from the values calculated for the healthy ones. In this way it has become possible to pinpoint precisely the locations of damage over the entire measured surface. All experimental investigations have been carried out for thin aluminium or composite plates. Damage has been simulated by a small additional mass attached on the plate surface or by a narrow notch cut. It has been shown that proposed method allows one to localise damage of various shapes and sizes within structural elements over the whole area under investigation.

Application of RMS for damage detection by guided elastic waves

Science.gov (United States)

Radzieński, M.; Doliński, Ł.; Krawczuk, M.; dot Zak, A.; Ostachowicz, W.

2011-07-01

This paper presents certain results of an experimental study related with a damage detection in structural elements based on deviations in guided elastic wave propagation patterns. In order to excite guided elastic waves within specimens tested piezoelectric transducers have been applied. As excitation signals 5 sine cycles modulated by Hanning window have been used. Propagation of guided elastic waves has been monitored by a scanning Doppler laser vibrometer. The time signals recorded during measurement have been utilised to calculate the values of RMS. It has turned out that the values of RMS differed significantly in damaged areas from the values calculated for the healthy ones. In this way it has become possible to pinpoint precisely the locations of damage over the entire measured surface. All experimental investigations have been carried out for thin aluminium or composite plates. Damage has been simulated by a small additional mass attached on the plate surface or by a narrow notch cut. It has been shown that proposed method allows one to localise damage of various shapes and sizes within structural elements over the whole area under investigation.

Low cycle fatigue: high cycle fatigue damage accumulation in a 304L austenitic stainless steel

International Nuclear Information System (INIS)

Lehericy, Y.

2007-05-01

The aim of this study was to evaluate the consequences of a Low Cycle Fatigue pre-damage on the subsequent fatigue limit of a 304L stainless steel. The effects of hardening and severe roughness (grinding) have also been investigated. In a first set of tests, the evolution of the surface damage induced by the different LCF pre-cycling was characterized. This has permitted to identify mechanisms and kinetics of damage in the plastic domain for different surface conditions. Then, pre-damaged samples were tested in the High Cycle Fatigue domain in order to establish the fatigue limits associated with each level of pre-damage. Results evidence that, in the case of polished samples, an important number of cycles is required to initiate surface cracks ant then to affect the fatigue limit of the material but, in the case of ground samples, a few number of cycles is sufficient to initiate cracks and to critically decrease the fatigue limit. The fatigue limit of pre-damaged samples can be estimated using the stress intensity factor threshold. Moreover, this detrimental effect of severe surface conditions is enhanced when fatigue tests are performed under a positive mean stress (author)

The DNA damage response during mitosis

International Nuclear Information System (INIS)

Heijink, Anne Margriet; Krajewska, Małgorzata; Vugt, Marcel A.T.M. van

2013-01-01

Cells are equipped with a cell-intrinsic signaling network called the DNA damage response (DDR). This signaling network recognizes DNA lesions and initiates various downstream pathways to coordinate a cell cycle arrest with the repair of the damaged DNA. Alternatively, the DDR can mediate clearance of affected cells that are beyond repair through apoptosis or senescence. The DDR can be activated in response to DNA damage throughout the cell cycle, although the extent of DDR signaling is different in each cell cycle phase. Especially in response to DNA double strand breaks, only a very marginal response was observed during mitosis. Early on it was recognized that cells which are irradiated during mitosis continued division without repairing broken chromosomes. Although these initial observations indicated diminished DNA repair and lack of an acute DNA damage-induced cell cycle arrest, insight into the mechanistic re-wiring of DDR signaling during mitosis was only recently provided. Different mechanisms appear to be at play to inactivate specific signaling axes of the DDR network in mitosis. Importantly, mitotic cells not simply inactivate the entire DDR, but appear to mark their DNA damage for repair after mitotic exit. Since the treatment of cancer frequently involves agents that induce DNA damage as well as agents that block mitotic progression, it is clinically relevant to obtain a better understanding of how cancer cells deal with DNA damage during interphase versus mitosis. In this review, the molecular details concerning DDR signaling during mitosis as well as the consequences of encountering DNA damage during mitosis for cellular fate are discussed

The DNA damage response during mitosis

Energy Technology Data Exchange (ETDEWEB)

Heijink, Anne Margriet; Krajewska, Małgorzata; Vugt, Marcel A.T.M. van, E-mail: m.vugt@umcg.nl

2013-10-15

Cells are equipped with a cell-intrinsic signaling network called the DNA damage response (DDR). This signaling network recognizes DNA lesions and initiates various downstream pathways to coordinate a cell cycle arrest with the repair of the damaged DNA. Alternatively, the DDR can mediate clearance of affected cells that are beyond repair through apoptosis or senescence. The DDR can be activated in response to DNA damage throughout the cell cycle, although the extent of DDR signaling is different in each cell cycle phase. Especially in response to DNA double strand breaks, only a very marginal response was observed during mitosis. Early on it was recognized that cells which are irradiated during mitosis continued division without repairing broken chromosomes. Although these initial observations indicated diminished DNA repair and lack of an acute DNA damage-induced cell cycle arrest, insight into the mechanistic re-wiring of DDR signaling during mitosis was only recently provided. Different mechanisms appear to be at play to inactivate specific signaling axes of the DDR network in mitosis. Importantly, mitotic cells not simply inactivate the entire DDR, but appear to mark their DNA damage for repair after mitotic exit. Since the treatment of cancer frequently involves agents that induce DNA damage as well as agents that block mitotic progression, it is clinically relevant to obtain a better understanding of how cancer cells deal with DNA damage during interphase versus mitosis. In this review, the molecular details concerning DDR signaling during mitosis as well as the consequences of encountering DNA damage during mitosis for cellular fate are discussed.

Study on the estimation of safety margin of piping system against seismic loading. 1st report, damage observations of the straight pipes subjected to cyclic load amplitudes of various levels

International Nuclear Information System (INIS)

Nakamura, Izumi; Otani, Akihito; Shiratori, Masaki

2010-01-01

Fatigue failure accompanied by ratchet deformation is well known as one of the failure modes of pressurized pipes under high-level cyclic load. In this research, the process of failure of such pipes was investigated based on the experimental result in which a straight pipe failed by repeatedly increasing cyclic input displacement amplitude in stages. The strain behavior, moment-deflection relationship, and observed damage were compared with the stress level used in the seismic design of the piping system. As a result, no significant damage was observed and the moment-deflection relationship remained almost linear within the primary stress limit of 3S m , although the strain showed elastic-plastic behavior at some measurement points. In the experiment, damage was observed at the applied load levels of approximately 5S m of the primary stress, and 0.15 and more of the fatigue damage index, i.e., the usage factor based on the design. The test results showed that there is a certain time margin before failure occurs to actual piping systems, compared with its designed stress limitation. (author)

Damage accumulation and annealing in 6H-SiC irradiated with Si+

International Nuclear Information System (INIS)

Jiang, W.; Weber, W.J.; Thevuthasan, S.; McCready, D.E.

1998-01-01

Damage accumulation and annealing in 6H-silicon carbide (α-SiC) single crystals have been studied in situ using 2.0 MeV He + RBS in a left angle 0001 right angle -axial channeling geometry (RBS/C). The damage was induced by 550 keV Si + ion implantation (30 off normal) at a temperature of -110 C, and the damage recovery was investigated by subsequent isochronal annealing (20 min) over the temperature range from -110 C to 900 C. At ion fluences below 7.5 x 10 13 Si + /cm 2 (0.04 dpa in the damage peak), only point defects appear to be created. Furthermore, the defects on the Si sublattice can be completely recovered by thermal annealing at room temperature (RT), and recovery of defects on the C sublattice is suggested. At higher fluences, amorphization occurs; however, partial damage recovery at RT is still observed, even at a fluence of 6.6 x 10 14 Si + /cm 2 (0.35 dpa in the damage peak) where a buried amorphous layer is produced. At an ion fluence of 6.0 x 10 15 Si + /cm 2 (-90 C), an amorphous layer is created from the surface to a depth of 0.6 μm. Because of recovery processes at the buried crystalline-amorphous interface, the apparent thickness of this amorphous layer decreases slightly (<10%) with increasing temperature over the range from -90 C to 600 C. (orig.)

An investigation of laser processing of silica surfaces

International Nuclear Information System (INIS)

Weber, A.J.; Stewart, A.F.; Exarhos, G.J.; Stowell, W.K.

1988-01-01

An initial set of experiments has been conducted to determine the practicality of laser processing of optical substrates. In contrast to earlier work, a high average power CO 2 laser was used to flood load the entire surface of each test sample. Fused silica substrates were laser polished on both surfaces at power densities ranging from 150 to 350 W/cm 2 . During each test sequence sample surface temperatures were recorded using a thermal imaging system. Extensive pre- and post-test characterization revealed that surface roughness and scattering of bare silica surfaces were reduced while internal stress increased. Laser damage thresholds were found to increase only for certain conditions. Changes in the microstructure were observed. These preliminary experiments demonstrate that laser processing can dramatically improve the optical properties of fused silica substrates

Effects of ultrasonic instrumentation on enamel surfaces with various defects.

Science.gov (United States)

Kim, S-Y; Kang, M-K; Kang, S-M; Kim, H-E

2018-05-01

The aim of this study was to analyse the enamel damage caused by ultrasonic scaling of teeth with various enamel conditions that are difficult to identify by visual inspection, such as enamel cracks, early caries and resin restorations. In total, 120 tooth surfaces were divided into 4 experimental groups using a quantitative light-induced fluorescence-digital system: sound enamel group, enamel cracks group, early caries group and resin restoration group. A skilled dental hygienist performed ultrasonic scaling under a standardized set of conditions: a ≤ 15° angle between the scaler tip and tooth surface and 40-80 g of lateral pressure at the rate of 12 times/10 s. Following scaling, the depth of enamel damage was measured using a surface profilometer and observed using scanning electron microscopy (SEM). The damage depth was the greatest in the enamel cracks group (37.63 ± 34.42 μm), followed by the early caries group (26.81 ± 8.67 μm), resin restoration group (19.63 ± 6.73 μm) and the sound enamel group (17.00 ± 5.66 μm). The damage depth was significantly deeper in the enamel cracks and early caries groups than in the sound enamel group (P enamel loss in the enamel cracks, early caries and resin restoration groups. The results of this study suggest that ultrasonic scaling can cause further damage to teeth with enamel cracks, early caries and resin restorations. Therefore, accurate identification of tooth conditions and calculus before the initiation of ultrasonic scaling is necessary to minimize damage. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Microscopic observation of pattern attack by aggressive ions on finished surface of aluminium alloy sacrificial anode

International Nuclear Information System (INIS)

Zaifol Samsu; Muhammad Daud; Siti Radiah Mohd Kamarudin; Nur Ubaidah Saidin; Azali Muhammad; Mohd Shaari Ripin; Rusni Rejab; Mohd Shariff Sattar

2010-01-01

This paper presents the results of a microscopic observation on submerged finished surface of aluminium alloy sacrificial anode. Experimental tests were carried out on polished surface aluminium anode exposed to seawater containing aggressive ions in order to observe of pattern corrosion attack on corroding surface of anode. Results have shown, at least under the present testing condition, that surface of sacrificial anode were attack by an aggressive ion such as chloride along grain boundaries. In addition, results of microanalysis showed that the corrosion products on surface of aluminium alloy have Al, Zn and O element for all sample and within the pit was consists of Al, Zn, O and Cl element. (author)

Propagation of Reactions in Thermally-damaged PBX-9501

Energy Technology Data Exchange (ETDEWEB)

Tringe, J W; Glascoe, E A; Kercher, J R; Willey, T M; Springer, H K; Greenwood, D W; Molitoris, J D; Smilowitz, L; Henson, B F; Maienschein, J L

2010-03-05

A thermally-initiated explosion in PBX-9501 (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) is observed in situ by flash x-ray imaging, and modeled with the LLNL multi-physics arbitrary-Lagrangian-Eulerian code ALE3D. The containment vessel deformation provides a useful estimate of the reaction pressure at the time of the explosion, which we calculate to be in the range 0.8-1.4 GPa. Closely-coupled ALE3D simulations of these experiments, utilizing the multi-phase convective burn model, provide detailed predictions of the reacted mass fraction and deflagration front acceleration. During the preinitiation heating phase of these experiments, the solid HMX portion of the PBX-9501 undergoes a {beta}-phase to {delta}-phase transition which damages the explosive and induces porosity. The multi-phase convective burn model results demonstrate that damaged particle size and pressure are critical for predicting reaction speed and violence. In the model, energetic parameters are taken from LLNL's thermochemical-kinetics code Cheetah and burn rate parameters from Son et al. (2000). Model predictions of an accelerating deflagration front are in qualitative agreement with the experimental images assuming a mode particle diameter in the range 300-400 {micro}m. There is uncertainty in the initial porosity caused by thermal damage of PBX-9501 and, thus, the effective surface area for burning. To better understand these structures, we employ x-ray computed tomography (XRCT) to examine the microstructure of PBX-9501 before and after thermal damage. Although lack of contrast between grains and binder prevents the determination of full grain size distribution in this material, there are many domains visible in thermally damaged PBX-9501 with diameters in the 300-400 {micro}m range.

Damage-induced nonassociated inelastic flow in rock salt

International Nuclear Information System (INIS)

Chan, K.S.; Bodner, S.R.; Brodsky, N.S.; Fossum, A.F.; Munson, D.E.

1993-01-01

The multi-mechanism deformation coupled fracture model recently developed by CHAN, et al. (1992), for describing time-dependent, pressure-sensitive inelastic flow and damage evolution in crystalline solids was evaluated against triaxial creep experiments on rock salt. Guided by experimental observations, the kinetic equation and the flow law for damage-induced inelastic flow in the model were modified to account for the development of damage and inelastic dilatation in the transient creep regime. The revised model was then utilized to obtain the creep response and damage evolution in rock salt as a function of confining pressure and stress difference. Comparison between model calculation and experiment revealed that damage-induced inelastic flow is nonassociated, dilatational, and contributes significantly to the macroscopic strain rate observed in rock salt deformed at low confining pressures. The inelastic strain rate and volumetric strain due to damage decrease with increasing confining pressures, and all are suppressed at sufficiently high confining pressures

Wear and damage of articular cartilage with friction against orthopedic implant materials.

Science.gov (United States)

Oungoulian, Sevan R; Durney, Krista M; Jones, Brian K; Ahmad, Christopher S; Hung, Clark T; Ateshian, Gerard A

2015-07-16

The objective of this study was to measure the wear response of immature bovine articular cartilage tested against glass or alloys used in hemiarthroplasties. Two cobalt chromium alloys and a stainless steel alloy were selected for these investigations. The surface roughness of one of the cobalt chromium alloys was also varied within the range considered acceptable by regulatory agencies. Cartilage disks were tested in a configuration that promoted loss of interstitial fluid pressurization to accelerate conditions believed to occur in hemiarthroplasties. Results showed that considerably more damage occurred in cartilage samples tested against stainless steel (10 nm roughness) and low carbon cobalt chromium alloy (27 nm roughness) compared to glass (10 nm) and smoother low or high carbon cobalt chromium (10 nm). The two materials producing the greatest damage also exhibited higher equilibrium friction coefficients. Cartilage damage occurred primarily in the form of delamination at the interface between the superficial tangential zone and the transitional middle zone, with much less evidence of abrasive wear at the articular surface. These results suggest that cartilage damage from frictional loading occurs as a result of subsurface fatigue failure leading to the delamination. Surface chemistry and surface roughness of implant materials can have a significant influence on tissue damage, even when using materials and roughness values that satisfy regulatory requirements. Copyright © 2015 Elsevier Ltd. All rights reserved.

Wear and Damage of Articular Cartilage with Friction Against Orthopaedic Implant Materials

Science.gov (United States)

Oungoulian, Sevan R.; Durney, Krista M.; Jones, Brian K.; Ahmad, Christopher S.; Hung, Clark T.; Ateshian, Gerard A.

2015-01-01

The objective of this study was to measure the wear response of immature bovine articular cartilage tested against glass or alloys used in hemiarthroplasties. Two cobalt chromium alloys and a stainless steel alloy were selected for these investigations. The surface roughness of one of the cobalt chromium alloys was also varied within the range considered acceptable by regulatory agencies. Cartilage disks were tested in a configuration that promoted loss of interstitial fluid pressurization to accelerate conditions believed to occur in hemiarthroplasties. Results showed that considerably more damage occurred in cartilage samples tested against stainless steel (10 nm roughness) and low carbon cobalt chromium alloy (27 nm roughness) compared to glass (10 nm) and smoother low or high carbon cobalt chromium (10 nm). The two materials producing the greatest damage also exhibited higher equilibrium friction coefficients. Cartilage damage occurred primarily in the form of delamination at the interface between the superficial tangential zone and the transitional middle zone, with much less evidence of abrasive wear at the articular surface. These results suggest that cartilage damage from frictional loading occurs as a result of subsurface fatigue failure leading to the delamination. Surface chemistry and surface roughness of implant materials can have a significant influence on tissue damage, even when using materials and roughness values that satisfy regulatory requirements. PMID:25912663

3D cellular automata finite element (CAFE) modelling and experimental observation of damage in quasi-brittle nuclear materials: Indentation of a SiC-SiC-fibre ceramic matrix composite

International Nuclear Information System (INIS)

Saucedo Mora, Luis; Mostafavi, Mahmoud; Marrow, T. James; Khoshkhou, Danial; Connolly, Brian; Reinhard, Christina; Atwood, Robert; Zhao, Shuang

2015-01-01

Cellular automata integrated with finite elements (CAFE) have been used to develop a method to account for the effect of microstructure on quasi-brittle damage development. The microstructure is simulated explicitly by subdividing a finite element into smaller cells. A heterogeneous structure is created from key cells (seeds) using defined characteristics; the influence of the initial finite element mesh is effectively removed during the development of the microstructure. Graded microstructures, textures, particle anisotropy and multiple phases can be readily simulated, such as those in composites and porous materials. A mesh-free framework has been developed to compute the damage development through the microstructure, using cellular automata. With this method, we can study the development of discontinuous cracking and damage coalescence, and its sensitivity to microstructure. Experiments have been carried out to observe the three-dimensional development of damage, using high-resolution synchrotron X-ray computed tomography and digital volume correlation to observe Hertzian indentation of a SiC-SiC fibre composite, quantifying damage by measurement of the displacement fields within the material. The results demonstrate the applicability of the modelling strategy to damage development, and show how model input data may be obtained from small specimen tests, which could be performed at elevated temperatures with irradiated materials. (authors)

Dislocation dynamics modelling of radiation damage in thin films

International Nuclear Information System (INIS)

Ferroni, Francesco; Tarleton, Edmund; Fitzgerald, Steven

2014-01-01

Transmission electron microscopy is a key tool for the extraction of information on radiation damage, the understanding of which is critical for materials development for nuclear fusion and fission reactors. Dislocations in TEM samples are subject to strong image forces, owing to the nanometric sample thicknesses, which may introduce artifacts in the damage analysis. Using dislocation dynamics, we elucidate the roles played by dislocation–surface interactions, dislocation–dislocation interactions and self-interactions due to climb for loop types observed in TEM. Comparisons with analytic solutions for a dislocation loop and an edge dislocation in a half-space are included, and the relationship between glide force and loop tilt examined. The parameters for convergence of the zero-traction boundary conditions are obtained, after which the evolution of dislocation structures in a thin film is studied. It is found that three main length scales govern the physical processes: the image force is governed by the distance of the loop from the surface and scales with the film thickness; the glide force is governed by the image stress as well as the loop–loop interaction stress which is in turn governed by the loop spacing L∼1/√ρ, where ρ is the loop density; finally, the climb force depends on the loop size. The three forces compete and their relative magnitudes define the evolution pathway of the dislocation structure. (paper)

Multi Resolution In-Situ Testing and Multiscale Simulation for Creep Fatigue Damage Analysis of Alloy 617

Energy Technology Data Exchange (ETDEWEB)

Liu, Yongming [Arizona State Univ., Tempe, AZ (United States). School for Engineering of Matter, Transport and Energy; Oskay, Caglar [Vanderbilt Univ., Nashville, TN (United States). Dept. of Civil and Environmental Engineering

2017-04-30

This report outlines the research activities that were carried out for the integrated experimental and simulation investigation of creep-fatigue damage mechanism and life prediction of Nickel-based alloy, Inconel 617 at high temperatures (950° and 850°). First, a novel experimental design using a hybrid control technique is proposed. The newly developed experimental technique can generate different combinations of creep and fatigue damage by changing the experimental design parameters. Next, detailed imaging analysis and statistical data analysis are performed to quantify the failure mechanisms of the creep fatigue of alloy 617 at high temperatures. It is observed that the creep damage is directly associated with the internal voids at the grain boundaries and the fatigue damage is directly related to the surface cracking. It is also observed that the classical time fraction approach does not has a good correlation with the experimental observed damage features. An effective time fraction parameter is seen to have an excellent correlation with the material microstructural damage. Thus, a new empirical damage interaction diagram is proposed based on the experimental observations. Following this, a macro level viscoplastic model coupled with damage is developed to simulate the stress/strain response under creep fatigue loadings. A damage rate function based on the hysteresis energy and creep energy is proposed to capture the softening behavior of the material and a good correlation with life prediction and material hysteresis behavior is observed. The simulation work is extended to include the microstructural heterogeneity. A crystal plasticity finite element model considering isothermal and large deformation conditions at the microstructural scale has been developed for fatigue, creep-fatigue as well as creep deformation and rupture at high temperature. The model considers collective dislocation glide and climb of the grains and progressive damage accumulation of

The observed sensitivity of the global hydrological cycle to changes in surface temperature

International Nuclear Information System (INIS)

Arkin, Phillip A; Janowiak, John; Smith, Thomas M; Sapiano, Mathew R P

2010-01-01

Climate models project large changes in global surface temperature in coming decades that are expected to be accompanied by significant changes in the global hydrological cycle. Validation of model simulations is essential to support their use in decision making, but observing the elements of the hydrological cycle is challenging, and model-independent global data sets exist only for precipitation. We compute the sensitivity of the global hydrological cycle to changes in surface temperature using available global precipitation data sets and compare the results against the sensitivities derived from model simulations of 20th century climate. The implications of the results for the global climate observing system are discussed.

How well will the Surface Water and Ocean Topography (SWOT) mission observe global reservoirs?

Science.gov (United States)

Solander, Kurt C.; Reager, John T.; Famiglietti, James S.

2016-03-01

Accurate observations of global reservoir storage are critical to understand the availability of managed water resources. By enabling estimates of surface water area and height for reservoir sizes exceeding 250 m2 at a maximum repeat orbit of up to 21 days, the NASA Surface Water and Ocean Topography (SWOT) satellite mission (anticipated launch date 2020) is expected to greatly improve upon existing reservoir monitoring capabilities. It is thus essential that spatial and temporal measurement uncertainty for water bodies is known a priori to maximize the utility of SWOT observations as the data are acquired. In this study, we evaluate SWOT reservoir observations using a three-pronged approach that assesses temporal aliasing, errors due to specific reservoir spatial properties, and SWOT performance over actual reservoirs using a combination of in situ and simulated reservoir observations from the SWOTsim instrument simulator. Results indicate temporal errors to be less than 5% for the smallest reservoir sizes (100 km2). Surface area and height errors were found to be minimal (area SWOT, this study will be have important implications for future applications of SWOT reservoir measurements in global monitoring systems and models.

Evaluation of Oceanic Surface Observation for Reproducing the Upper Ocean Structure in ECHAM5/MPI-OM

Science.gov (United States)

Luo, Hao; Zheng, Fei; Zhu, Jiang

2017-12-01

Better constraints of initial conditions from data assimilation are necessary for climate simulations and predictions, and they are particularly important for the ocean due to its long climate memory; as such, ocean data assimilation (ODA) is regarded as an effective tool for seasonal to decadal predictions. In this work, an ODA system is established for a coupled climate model (ECHAM5/MPI-OM), which can assimilate all available oceanic observations using an ensemble optimal interpolation approach. To validate and isolate the performance of different surface observations in reproducing air-sea climate variations in the model, a set of observing system simulation experiments (OSSEs) was performed over 150 model years. Generally, assimilating sea surface temperature, sea surface salinity, and sea surface height (SSH) can reasonably reproduce the climate variability and vertical structure of the upper ocean, and assimilating SSH achieves the best results compared to the true states. For the El Niño-Southern Oscillation (ENSO), assimilating different surface observations captures true aspects of ENSO well, but assimilating SSH can further enhance the accuracy of ENSO-related feedback processes in the coupled model, leading to a more reasonable ENSO evolution and air-sea interaction over the tropical Pacific. For ocean heat content, there are still limitations in reproducing the long time-scale variability in the North Atlantic, even if SSH has been taken into consideration. These results demonstrate the effectiveness of assimilating surface observations in capturing the interannual signal and, to some extent, the decadal signal but still highlight the necessity of assimilating profile data to reproduce specific decadal variability.