WorldWideScience

Sample records for aeroengines surface damage

  1. Luster Polish Strengthening Treatment for Raceway Surface of Aeroengine Bearings

    Institute of Scientific and Technical Information of China (English)

    DENG Si-er; TENG Hong-fei; MA Fu-jian; HAO Jian-jun; CHEN Tao

    2007-01-01

    A new surface strengthening technology, luster polish strengthening treatnent, was proposed to treat the raceway surface of aeroengine bearings (9Cr18Mo) with the centrifugal strengthening machine exclusively designed for luster polish strengthening treatment. The experimental results showed that luster polish strengthening treatment produced a compressive residual stress layer with a depth of over 80 μm below the surface of the bearing raceway, and thus effectively removed the metamorphic layer in the raceway surface. After luster polish strengthening treatment, the average surface hardness of the aeroengine bearing raceway was increased from 61.02 HRC to 63.01 HRC, the surface roughness was reduced from 0.06 μm to 0.03 μm, and the contact fatigue life of the aeroengine bearings was improved by about 90%, with the dispersion of fatigue life being reduced remarkably.Theoretical calculation result agrees with that obtained by experiment.

  2. Foreign Object Damage to Fan Rotor Blades of Aeroengine Part Ⅰ: Experimental Study of Bird Impact

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The conditions of experiment for bird impact to blades have been improved. The experiment of bird impact to the fan rotor blades of an aeroengine is carried out. Through analyzing the transient state response of blades impacted by bird and the change of blade profile before and after the impact, the anti-bird impact performance of blades in the first fan rotor is verified. The basis of anti-foreign object damage design for the fan rotor blades of an aeroengine is provided.

  3. Vibration reliability analysis for aeroengine compressor blade based on support vector machine response surface method

    Institute of Scientific and Technical Information of China (English)

    GAO Hai-feng; BAI Guang-chen

    2015-01-01

    To ameliorate reliability analysis efficiency for aeroengine components, such as compressor blade, support vector machine response surface method (SRSM) is proposed. SRSM integrates the advantages of support vector machine (SVM) and traditional response surface method (RSM), and utilizes experimental samples to construct a suitable response surface function (RSF) to replace the complicated and abstract finite element model. Moreover, the randomness of material parameters, structural dimension and operating condition are considered during extracting data so that the response surface function is more agreeable to the practical model. The results indicate that based on the same experimental data, SRSM has come closer than RSM reliability to approximating Monte Carlo method (MCM); while SRSM (17.296 s) needs far less running time than MCM (10958 s) and RSM (9840 s). Therefore, under the same simulation conditions, SRSM has the largest analysis efficiency, and can be considered a feasible and valid method to analyze structural reliability.

  4. Foreign Object Damage to Fan Rotor Blades of Aeroengine Part Ⅱ: Numerical Simulation of Bird Impact

    Institute of Scientific and Technical Information of China (English)

    Guan Yupu; Zhao Zhenhua; Chen Wei; Gao Deping

    2008-01-01

    Bird impact is one of the most dangerous threats to flight safety. The consequences of bird impact can be severe and, therefore, the aircraft components have to be certified for a proven level of bird impact resistance before being put into service. The fan rotor blades of aeroengine are the components being easily impacted by birds. It is necessary to ensure that the fan rotor blades should have adequate resistance against the bird impact, to reduce the flying accidents caused by bird impacts. Using the contacting-impacting algorithm, the numerical simulation is carried out to simulate bird impact. A three-blade computational model is set up for the fan rotor blade having shrouds. The transient response curves of the points corresponding to measured points in experiments, displacements and equivalent stresses on the blades are obtained during the simulation. From the comparison of the transient response curves obtained from numerical simulation with that obtained from experiments, it can be found that the variations in measured points and the corresponding points of simulation are basically the same. The deforming process, the maximum displacements and the maximum equivalent stresses on blades are analyzed. The numerical simulation verifies and complements the experiment results.

  5. Surface integrity of GH4169 affected by cantilever finish grinding and the application in aero-engine blades

    Institute of Scientific and Technical Information of China (English)

    Li Xun; Ma Shuang; Meng Fanjun

    2015-01-01

    GH4169 is the main material for aero-engine blades and integrated blisks. Because GH4169 has a poor milling performance, the profile precision and surface integrity of blades and integrated blisks are difficult to be met by utilizing the conventional milling process, which directly influence the global performance and reliability of aero-engines. Through grinding experiments on parameters and surface integrity optimization, the helical cantilever grinding process utilizing a 300# CBN RB wheel is presented and applied in finish machining of GH4169 blades. The profile errors of the blade surface are within ±0.01 mm, the roughness is less than 0.4 lm, the residual compressive stresses and the hardening rate are appropriate, there are no phenomena of burr and smearing with the grinding chips, and the leading/trailing edge can be smoothly connected with the suction/pressure surface. All the experimental results indicate that this grinding process is greatly suitable for the profile finish machining of GH4169 blades.

  6. Reliability analysis for aeroengine turbine disc fatigue life with multiple random variables based on distributed collaborative response surface method

    Institute of Scientific and Technical Information of China (English)

    高海峰; 白广忱; 高阳; 鲍天未

    2015-01-01

    The fatigue life of aeroengine turbine disc presents great dispersion due to the randomness of the basic variables, such as applied load, working temperature, geometrical dimensions and material properties. In order to ameliorate reliability analysis efficiency without loss of reliability, the distributed collaborative response surface method (DCRSM) was proposed, and its basic theories were established in this work. Considering the failure dependency among the failure modes, the distributed response surface was constructed to establish the relationship between the failure mode and the relevant random variables. Then, the failure modes were considered as the random variables of system response to obtain the distributed collaborative response surface model based on structure failure criterion. Finally, the given turbine disc structure was employed to illustrate the feasibility and validity of the presented method. Through the comparison of DCRSM, Monte Carlo method (MCM) and the traditional response surface method (RSM), the results show that the computational precision for DCRSM is more consistent with MCM than RSM, while DCRSM needs far less computing time than MCM and RSM under the same simulation conditions. Thus, DCRSM is demonstrated to be a feasible and valid approach for improving the computational efficiency of reliability analysis for aeroengine turbine disc fatigue life with multiple random variables, and has great potential value for the complicated mechanical structure with multi-component and multi-failure mode.

  7. Surface integrity of GH4169 affected by cantilever finish grinding and the application in aero-engine blades

    Directory of Open Access Journals (Sweden)

    Li Xun

    2015-10-01

    Full Text Available GH4169 is the main material for aero-engine blades and integrated blisks. Because GH4169 has a poor milling performance, the profile precision and surface integrity of blades and integrated blisks are difficult to be met by utilizing the conventional milling process, which directly influence the global performance and reliability of aero-engines. Through grinding experiments on parameters and surface integrity optimization, the helical cantilever grinding process utilizing a 300# CBN RB wheel is presented and applied in finish machining of GH4169 blades. The profile errors of the blade surface are within ±0.01 mm, the roughness is less than 0.4 μm, the residual compressive stresses and the hardening rate are appropriate, there are no phenomena of burr and smearing with the grinding chips, and the leading/trailing edge can be smoothly connected with the suction/pressure surface. All the experimental results indicate that this grinding process is greatly suitable for the profile finish machining of GH4169 blades.

  8. Surface contamination initiated laser damage

    International Nuclear Information System (INIS)

    We are engaged in a comprehensive effort to understand and model the initiation and growth of laser damage initiated by surface contaminants. This includes, for example, the initial absorption by the contaminant, heating and plasma generation, pressure and thermal loading of the transparent substrate, and subsequent shockwave propagation, ''splashing'' of molten material and possible spallation, optical propagation and scattering, and treatment of material fracture. The integration use of large radiation hydrodynamics codes, optical propagation codes and material strength codes enables a comprehensive view of the damage process The following picture of surface contaminant initiated laser damage is emerging from our simulations. On the entrance optical surface, small particles can ablate nearly completely. In this case, only relatively weak shockwaves are launched into the substrate, but some particulate material may be left on the surface to act as a diffraction mask and cause further absorption. Diffraction by wavelength scale scattering centers can lead to significant intensity modulation. Larger particles will not be completely vaporized. The shockwave generated in this case 1642is larger and can lead to spallation of contaminant material which then may be deposited in the substrate. A gaseous atmosphere can lead to radiation trapping with concomitant increases in temperature and pressure near the surface. In addition, supersonic ionization waves in air may be generated which greatly extend the plasma plume spatially and temporally. Contaminants on the exit optical surface behave differently. They tend to heat and pop off completely in which case significant damage may not occur. Since plasma formed at the interface of the optic and absorbing particle is confined, much stronger pressures are generated in this case. Imaging of contaminants resulting in ''writing'' a diffraction pattern on the exit surface due to contamination on the entrance surface has been

  9. Directivity of a simplified aeroengine

    OpenAIRE

    Mattei, Pierre-Olivier

    2006-01-01

    International audience; This paper presents theoretical and numerical results on the high frequency directivity of an aeroengine under flight conditions. In this paper, two different theories, based on a Kirchhoff approximation for semi-infinite cylinders, are combined to obtain the far field sound pressure radiated into the whole surrounding space. Although the geometric description of the engine is simplified - in particular, the annular exhaust is not taken into account - it includes some ...

  10. Development in Geared Turbofan Aeroengine

    Science.gov (United States)

    Mohd Tobi, A. L.; Ismail, A. E.

    2016-05-01

    This paper looks into the implementation of epicyclic gear system to the aeroengine in order to increase the efficiency of the engine. The improvement made is in the direction of improving fuel consumption, reduction in pollutant gasses and perceived noise. Introduction of epicyclic gear system is capable to achieve bypass ratio of up to 15:1 with the benefits of weight and noise reduction. Radical new aircraft designs and engine installation are being studied to overcome some of the challenges associated with the future geared turbofan and open-rotor engine.

  11. 航空发动机机匣损伤容限评估及剩余寿命预测%Determination of damage tolerance and remaining life for aeroengine crankcase

    Institute of Scientific and Technical Information of China (English)

    秦丽晔; 吴素君; 赵海涛; 刘颖

    2011-01-01

    In order to ensure the safety of aircraft,fracture assessment for an aeroengine crankcase was carried out.Based on finite element method,a model for the local crankcase fitting seat was established and the geometry factor Y for different crack lengths was obtained.Using the procedure of BS7910,crankcase damage tolerance was calculated and verified by test,the critical allowable crack length is 84.8 mm and the remaining strength decreases with the increase of crack length.The allowable crack dimension and residual strength of weld are smaller than that of parent metal.The test results are in good agreement with the calculated results when crack is small.The remaining life of crankcase was also calculated using Paris formula.%使用有限元的方法,建立了某航空发动机机匣安装座处局部模型,计算得到了不同尺寸裂纹的应力强度因子的形状因子Y.基于BS7910评定方法,利用失效评估图(FAD,Failure Assessment Diagram)确定了机匣安装座结构在工作应力下的可接受裂纹尺寸为84.8 mm,结构的剩余强度随裂纹尺寸的增加而显著降低,焊缝较母材具有更低的损伤容限和剩余强度.使用缩小宽度模拟验证件模拟工作状态载荷进行了验证试验,当裂纹尺寸与试样宽度比值较小时,与模拟验证件的评估结果基本吻合.根据Paris公式,构件在工作应力下的剩余寿命为74238周次.

  12. Reliability analysis of aero-engine blades considering nonlinear strength degeneration

    Institute of Scientific and Technical Information of China (English)

    Lin Jiewei; Zhang Junhong; Yang Shuo; Bi Fengrong

    2013-01-01

    To comprehensively consider the effects of strength degeneration and failure correlation,an improved stress-strength interference (SSI) model is proposed to analyze the reliability of aeroengine blades with the fatigue failure mode.Two types of TC4 alloy experiments are conducted for the study on the damage accumulation law.All the parameters in the nonlinear damage model are obtained by the tension-compression fatigue tests,and the accuracy of the nonlinear damage model is verified by the damage tests.The strength degeneration model is put forward on the basis of the Chaboche nonlinear damage theory and the Griffith fracture criterion,and determined by measuring the fatigue toughness during the tests.From the comparison of two kinds of degeneration models based on the Miner's linear law and the nonlinear damage model respectively,the nonlinear model has a significant advantage on prediction accuracy especially in the later period of life.A time-dependent SSI reliability model is established.By computing the stress distribution using the finite element (FE) technique,the reliability of a single blade during the whole service life is obtained.Considering the failure correlation of components,a modified reliability model of aero-engine blades with common cause failure (CCF) is presented.It shows a closer and more reasonable process with the actual working condition.The improved reliability model is illustrated to be applied to aero-engine blades well,and the approach purposed in this paper is suitable for any actual machinery component of aero-engine rotor systems.

  13. Efficient and environmentally friendly aero-engine

    Energy Technology Data Exchange (ETDEWEB)

    Pellischek, G. [MTU, Engine Industry (Country unknown/Code not available)

    1998-03-01

    The Thematic Network on the `Efficient and Environmentally Friendly Aero-engine` integrates the various research projects of the European aero-engine industry conducted under the European Commission Fourth Framework Programme in order to emphasize the targeted character of the research work, to encourage mutual exchange of information between related research areas and to improve the strategic co-ordination at a European level. By introducing specific clusters on Turbomachinery Design Tools, Advanced Materials and Low Emission Combustor Technologies the majority of essential engine projects will be covered and thus enable a broadly based cross-flow of information between newly emerging projects from the latest call for proposals and those already active following the launch of the current Framework Programme. Research projects on engine noise will be included in the aircraft noise cluster `X-Noise`, which will maintain informal links with the aero-engine TRA (Targeted Research Action). The relation with the AERONET-TRA and more fundamental climate research will be maintained via the cluster on the Low Emission Combustor Technologies. Strategic cluster and TRA meetings of all parties concerned will serve as the mechanism for information exchange inside the engine family and also with the European Commission and, where appropriate, the public. The aero-engine TRA will be co-ordinated by MTU, who currently hold the chair of the Engine Industry Management Group (EIMG) with strong support from a steering committee incorporating the other EIMG representatives. (author)

  14. Aero-Engine Condition Monitoring Based on Support Vector Machine

    Science.gov (United States)

    Zhang, Chunxiao; Wang, Nan

    The maintenance and management of civil aero-engine require advanced monitor approaches to estimate aero-engine performance and health in order to increase life of aero-engine and reduce maintenance costs. In this paper, we adopted support vector machine (SVM) regression approach to monitor an aero-engine health and condition by building monitoring models of main aero-engine performance parameters(EGT, N1, N2 and FF). The accuracy of nonlinear baseline models of performance parameters is tested and the maximum relative error does not exceed ±0.3%, which meets the engineering requirements. The results show that SVM nonlinear regression is an effective method in aero-engine monitoring.

  15. [Remote passive sensing of aeroengine exhausts using FTIR system].

    Science.gov (United States)

    Xia, Qing; Zuo, Hong-Fu; Li, Shao-Cheng; Wen, Zhen-Hua; Li, Yao-Hua

    2009-03-01

    The traditional method of measuring the aeroengine exhausts is intrusive gas sampling analysis techniques. The disadvantages of the techniques include complex system, difficult operation, high costs and potential danger because of back-pressure effects. The non-intrusive methods have the potential to overcome these problems. So the remote FTIR passive sensing is applied to monitor aeroengine exhausts and determine the concentration of the exhausts gases of aeroengines. The principle of FTIR remote passive sensing is discussed. The model algorithm for the calibration of FTIR system, the radiance power distribution and gas concentration are introduced. TENSOR27 FTIR-system was used to measure the spectra of infrared radiation emitted by the hot gases of exhausts in a test rig. The emission spectra of exhausts were obtained under different thrusts. By analyzing the spectra, the concentrations of CO2, CO and NO concentration were calculated under 4 thrusts. Researches on the determination of concentration of the exhausts gases of aeroengines by using the remote FTIR sensing are still in early stage in the domestic aeronautics field. The results of the spectra and concentration in the aeroengine test are published for the first time. It is shown that the remote FTIR passive sensing techniques have a great future in monitoring the hot gas of the aeroengines exhausts.

  16. Recent trends in superalloys research for critical aero-engine components

    Energy Technology Data Exchange (ETDEWEB)

    Remy, Luc [Mine ParisTech, CNRS UMR 7633, 91 - Evry (France). Centre des Materiaux; Guedou, Jean-Yves [Snecma Safran Group, Moissy-Cramayel (France). Materials and Processes Dept.

    2010-07-01

    This paper is a brief survey of common research activity on superalloys for aero-engines between Snecma and Mines ParisTech Centre des Materiaux during recent years. First in disks applications, the development of new powder metallurgy superalloys is shown. Then grain boundary engineering is investigated in a wrought superalloy. Secondly, design oriented research on single crystals blades is shown: a damage model for low cycle fatigue is used for life prediction when cracks initiated at casting pores. The methodology developed for assessing coating life is illustrated for thermal barrier coating deposited on AMI single crystal superalloy. (orig.)

  17. Bacterial Cell Surface Damage Due to Centrifugal Compaction

    NARCIS (Netherlands)

    Peterson, Brandon W.; Sharma, Prashant K.; van der Mei, Henny C.; Busscher, Henk J.

    2012-01-01

    Centrifugal damage has been known to alter bacterial cell surface properties and interior structures, including DNA. Very few studies exist on bacterial damage caused by centrifugation because of the difficulty in relating centrifugation speed and container geometry to the damage caused. Here, we pr

  18. Prediction Method for the Surface Damage in Splined Couplings

    OpenAIRE

    Cuffaro, Vincenzo

    2013-01-01

    The primary purpose of my PhD thesis was to develop design criteria and to verify procedures about fretting wear, that are applicable to crowned spline couplings of a power transmission system of the aeroengines. Fretting is a very complex phenomenon being influenced by many factors, the most important being the presence or absence of lubrication, the load distribution (contact pressure) and the sliding between the bodies. Therefore, the study of fretting needs a deep knowledge of these three...

  19. Exogenous glycosaminoglycans coat damaged bladder surfaces in experimentally damaged mouse bladder

    Directory of Open Access Journals (Sweden)

    Hurst Robert E

    2005-03-01

    Full Text Available Abstract Background Interstital cystitis is often treated with exogenous glycosaminoglycans such as heparin, chondroitin sulphate (Uracyst, hyaluronate (Cystistat or the semi-synthetic pentosan polysulphate (Elmiron. The mechanism of action is presumed to be due to a coating of the bladder surface to replace the normally present chondroitin sulphate and heparan sulphate lost as a result of the disease. This study used fluorescent labelled chondroitin sulphate to track the distribution of glycosaminoglycans administered intravesically to mouse bladder that had been damaged on the surface. Methods The surfaces of mouse bladders were damaged by 3 mechanisms – trypsin, 10 mM HCl, and protamine sulphate. Texas Red-labeled chondroitin sulphate was instilled into the bladders of animals with damaged bladders and controls instilled only with saline. Bladders were harvested, frozen, and sectioned for examination by fluorescence. Results The normal mouse bladder bound a very thin layer of the labelled chondroitin sulphate on the luminal surface. Trypsin- and HCl-damaged bladders bound the labelled chondroitin sulphate extensively on the surface with little penetration into the bladder muscle. Protamine produced less overt damage, and much less labelling was seen, presumably due to loss of the label as it complexed with the protamine intercalated into the bladder surface. Conclusion Glycosaminoglycan administered intravesically does bind to damaged bladder. Given that the changes seen following bladder damage resemble those seen naturally in interstitial cystitis, the mechanisms proposed for the action of these agents is consistent with a coating of damaged bladder.

  20. Multidisciplinary Design Optimization on Conceptual Design of Aero-engine

    Science.gov (United States)

    Zhang, Xiao-bo; Wang, Zhan-xue; Zhou, Li; Liu, Zeng-wen

    2016-06-01

    In order to obtain better integrated performance of aero-engine during the conceptual design stage, multiple disciplines such as aerodynamics, structure, weight, and aircraft mission are required. Unfortunately, the couplings between these disciplines make it difficult to model or solve by conventional method. MDO (Multidisciplinary Design Optimization) methodology which can well deal with couplings of disciplines is considered to solve this coupled problem. Approximation method, optimization method, coordination method, and modeling method for MDO framework are deeply analyzed. For obtaining the more efficient MDO framework, an improved CSSO (Concurrent Subspace Optimization) strategy which is based on DOE (Design Of Experiment) and RSM (Response Surface Model) methods is proposed in this paper; and an improved DE (Differential Evolution) algorithm is recommended to solve the system-level and discipline-level optimization problems in MDO framework. The improved CSSO strategy and DE algorithm are evaluated by utilizing the numerical test problem. The result shows that the efficiency of improved methods proposed by this paper is significantly increased. The coupled problem of VCE (Variable Cycle Engine) conceptual design is solved by utilizing improved CSSO strategy, and the design parameter given by improved CSSO strategy is better than the original one. The integrated performance of VCE is significantly improved.

  1. A Rapid Method to Achieve Aero-Engine Blade Form Detection

    Directory of Open Access Journals (Sweden)

    Bin Sun

    2015-06-01

    Full Text Available This paper proposes a rapid method to detect aero-engine blade form, according to the characteristics of an aero-engine blade surface. This method first deduces an inclination error model in free-form surface measurements based on the non-contact laser triangulation principle. Then a four-coordinate measuring system was independently developed, a special fixture was designed according to the blade shape features, and a fast measurement of the blade features path was planned. Finally, by using the inclination error model for correction of acquired data, the measurement error that was caused by tilt form is compensated. As a result the measurement accuracy of the Laser Displacement Sensor was less than 10 μm. After the experimental verification, this method makes full use of optical non-contact measurement fast speed, high precision and wide measuring range of features. Using a standard gauge block as a measurement reference, the coordinate system conversion data is simple and practical. It not only improves the measurement accuracy of the blade surface, but also its measurement efficiency. Therefore, this method increases the value of the measurement of complex surfaces.

  2. Mining-induced surface damage and the study of countermeasures

    International Nuclear Information System (INIS)

    Coal constitutes China's major energy resource. The majority of the coal is produced from underground mining operations. Surface subsidence may amount to 80% of the thickness of the seam mined, while the subsided volume is around 60% of the mined volume underground. An area of 20 hectares of land will be affected with each 1 million tons of coal mined, thereby causing severe surface damage. Following a description of the characteristics of surface damages due to underground mining disturbance, this paper elaborates on the damage prediction method, standards applied for evaluating the damages experienced by surface buildings, land reclamation methods in subsided area, measures for reinforcing and protecting buildings in mining-affected areas, and performance of antideformation buildings

  3. Generic methods for aero-engine exhaust emission prediction

    NARCIS (Netherlands)

    Shakariyants, S.A.

    2008-01-01

    In the thesis, generic methods have been developed for aero-engine combustor performance, combustion chemistry, as well as airplane aerodynamics, airplane and engine performance. These methods specifically aim to support diverse emission prediction studies coupled with airplane and engine simulation

  4. Influence of Damage Evolution on the Failure Surface of Concrete

    Institute of Scientific and Technical Information of China (English)

    LUO Xin; WEI Jun

    2006-01-01

    The damage which represents the alternation of internal state of material was introduced to concrete strength theory according to the theory of mechanics of continuous medium and the failure criterion of deteriorated concrete was discussions. In the tests, ultrasonic velocity is used to establish the damage variable and to establish the damage-coupled failure criterion of concrete under freeze-thaw. The results show that the failure surface is gradually shrinking with the increase of freeze-thaw times. Furthermore, by the comparison between the theoretical data and the testing data from the literature, the rationality of strength theory proposed in the paper acquire confirmation. The damagecoupled failure criterion presented here can indicate the influence of damage evolution on the failure surface of concrete.

  5. Transfer element method with application to acoustic design of aeroengine nacelle

    Directory of Open Access Journals (Sweden)

    Wang Xiaoyu

    2015-04-01

    Full Text Available In the present survey, various methods for the acoustic design of aeroengine nacelle are first briefly introduced along with the comments on their advantages and disadvantages for practical application, and then detailed analysis and discussion focus on a kind of new method which is called “transfer element method” (TEM with emphasis on its application in the following three problems: turbomachinery noise generations, sound transmission in ducts and radiation from the inlet and outlet of ducts, as well as the interaction between them. In the theoretical frame of the TEM, the solution of acoustic field in an infinite duct with stator sound source or liner is extended to that in a finite domain with all knows and unknowns on the interface plane, and the relevant acoustic field is solved by setting up matching equation. In addition, based on combining the TEM with the boundary element method (BEM by establishing the pressure and its derivative continuum conditions on the inlet and outlet surface, the sound radiation from the inlet and outlet of ducts can also be investigated. Finally, the effects of various interactions between the sound source and acoustic treatment have been discussed in this survey. The numerical examples indicate that it is quite important to consider the effect of such interactions on sound attenuation during the acoustic design of aeroengine nacelle.

  6. Research on Time-Synchronization-Based Test and Control System of Aeroengine

    Institute of Scientific and Technical Information of China (English)

    WU Wen-jie; QIN Dong-xing; DONG Wei

    2004-01-01

    This paper presents a method of NTP-based time synchronization and a strategy of master-slave server structured time synchronization to ensure the test and control system of aeroengine to be time-synchronized. Based on time synchronization, the hierarchy and the integration of the measurement and control system of aeroengine are investigated. In result, our method is successfully applied for multiple front-end tests in a simulative altitude test facility of aeroengine.

  7. Application of Interval Multi-attribute Decision-Making Method to Aeroengine Performance Ranking

    Institute of Scientific and Technical Information of China (English)

    Zhang Haijun; Zuo Hongfu; Liang Jian

    2006-01-01

    In view of the uncertainty of the monitored performance parameters of aeroengines, the fluctuating scope of the monitored informarion during a period is taken as interval numbers, and the interval multi-attribute decision-making method is employed to predict the performance of aeroengine. The synthetic weights of interval numbers are obtained by calculating deviation degree and possibility degree. As an example of application, 5 performance parameters monitored on 10 CF6 aeroengines of China Eastern Airlines Co.,Ltd are adopted as decision attributes to verify the algorithm. The obtained synthetic ranking result shows the effectiveness and rationality of the proposed method in reflecting the performance status of aeroengins.

  8. Damage to underground coal mines caused by surface blasting

    International Nuclear Information System (INIS)

    An investigation of the potential damage to underground coal workings as a result of surface blasting at an opencast coal mine is described. Seismometers were installed in a worked out area of an underground mine, in the eastern Transvaal region of South Africa, and the vibration caused by nearby surface blasting recorded. These measurements were used to derive peak particle velocities. These velocities were correlated with observed damage underground in order to establish the allowable combination of the two blasting parameters of charge mass per relay, and blast-to-gage point distance. An upper limit of 110mm/sec peak particle velocity was found to be sufficient to ensure that the damage to the particular workings under consideration was minimal. It was further found that a cube-root scaling law provided a better fit to the field data than the common square-root law. 11 refs., 6 figs., 5 tabs

  9. Characterization of the damage produced on different materials surfaces

    International Nuclear Information System (INIS)

    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

  10. NDE of Damage in Aircraft Flight Control Surfaces

    Science.gov (United States)

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

    2007-03-01

    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.

  11. Surface modification of intraocular lenses to reduce corneal endothelial damage.

    Science.gov (United States)

    Knight, P M; Link, W J

    1979-04-01

    Two methods of surface modification of PMMA, permanent and temporary, were investigated for use on intraocular lenses to reduce corneal endothelial damage due to corneal-IOL touch. Monomer grafting using gamma irradiation was found to produce permanently hydrophilic surfaces. Temporary surface modifications developed and tested were peelable and dissolvable coatings. Test samples were touched to freshly excised rabbit corneas to evaluate the effectiveness of the various surface modifications in reducing endothelial cell damage. This touch testing was performed using static testing in which the test sample was touched to the cornea without movement and dynamic testing in which there was relative movement between the cornea and the test sample. While unmodified PMMA did significant cell damage in both static and dynamic tests perpamently modified (hydrophilic grafted) surfaces were found to perform well in the static, but not in the dynamic tests. Dissolvable coatings performed well in both tests, even with very thin coatings. There was little differentiation between the various water-soluble coatings tested. Due to its characteristics and rate of dissolution, polyvinyl alcohol appears to be an optimum material for coating IOLs. A series of in vitro and in vivo tests performed to assess its safety indicate that PVA is nontoxic and safe in animal eyes. PMID:479004

  12. High-Temperature Oxide Regrowth on Mechanically-Damaged Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL; Lowe, Tracie M [ORNL

    2008-01-01

    Here we report the effects of mechanical damage from a sharp stylus on the regrowth of oxide layers on a Ni-based superalloy known as Pyromet 80A . It was found that the oxide that reformed on the damaged portion of a pre-oxidized surface differed from that which formed on undamaged areas after the equal exposures to elevated temperature in air. These findings have broad implications for modeling the processes of material degradation in applications such as exhaust valves in internal combustion engines because they imply that static oxidation data for candidate materials may not adequately reflect their reaction to operating environments that involve both mechanical contact and oxidation.

  13. Diamond Processing by Focused Ion Beam - Surface Damage and Recovery

    CERN Document Server

    Bayn, Igal; Cytermann, Catherine; Meyler, Boris; Richter, Vladimir; Salzman, Joseph; Kalish, Rafi

    2011-01-01

    The Nitrogen Vacancy color center (NV-) in diamond is of great interest for novel photonic applications. Diamond nano-photonic structures are often implemented using Focused-Ion-Beam (FIB) processing, leaving a damaged surface which has a detrimental effect on the color center luminescence. The FIB processing effect on single crystal diamond surfaces and their photonic properties is studied by Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and photoluminescence (PL). Exposing the processed surface to hydrogen plasma, followed by chemical etching, drastically decreases implanted Ga concentration, resulting in a recovery of the NV- photo-emission and in a significant increase of the NV-/NV0 ratio.

  14. Slip compensation at fault damage zones along earthquake surface ruptures

    Science.gov (United States)

    Choi, J.; Kim, Y.

    2013-12-01

    Surface ruptures associated with earthquake faulting commonly comprise a number of segments, and the discontinuities form tip and linking damage zones, which are deformed regions consisting of secondary features. Stress transferring or releasing, when seismic waves pass through the discontinuities, could produce different slip features depending on rupture propagation or termination. Thus, slip patterns at fault damage zones can be one of the key factors to understand fault kinematics, fault evolution and, hence, earthquake hazard. In some previous studies (e.g. Peacock and Sanderson, 1991; Kim and Sanderson, 2005), slip distribution along faults to understand the connectivity or maturity of segmented faults system have commonly been analyzed based on only the main slip components (dip-slip or strike-slip). Secondary slip components, however, are sometimes dominant at fault damage zones, such as linkage and tip zones. In this study, therefore, we examine slip changes between both main and secondary slip components along unilaterally propagated coseismic strike-slip ruptures. Horizontal and vertical components of slip and the slip compensation patterns at tip and linking damage zones are various from slip deficit (decrease in both slip components) through slip compensation (increase of vertical slip with horizontal slip decrease) to slip neutral. Front and back tip zones, which are classified depending on main propagation direction of earthquake ruptures, show different slip patterns; slip compensation is observed at the frontal tip whilst slip deficit occurs at the back tip zone. Average values of the two slip components and their compensative patterns at linking damage zones are closely related with the ratio of length to width (L/W) of linkage geometry; the horizontal slip is proportional to the ratio of L/W, whilst the vertical slip shows little dependence on the value L/W. When the L/W is greater than ~2, average values of two slip components are almost similar

  15. Growth Characteristics and Mechanism of Surface and Bulk Damage in KDP and DKDP Crystals

    Institute of Scientific and Technical Information of China (English)

    HU Guo-Hang; ZHAO Yuan-An; SUN Shao-Tao; LI Da-Wei; LIU Xiao-Feng; SUN Xun; SHAO Jian-Da; FAN Zheng-Xiu

    2009-01-01

    By testing the number increase and size growth of surf ace and bulk laser induced damage in KDP and DKDP crystals,we observe different growth characteristics of surface and bulk damage under multiple 355 nm laser irradiations.The size of the surface damage grows exponentially,but that of the bulk damage does not grow.In contrast,the bulk damage number increases,but that of surface damage does not increase significantly.We attribute the differences to the different formation of the damage initiators and the different damage testing volumes.

  16. A response surface methodology based damage identification technique

    International Nuclear Information System (INIS)

    Response surface methodology (RSM) is a combination of statistical and mathematical techniques to represent the relationship between the inputs and outputs of a physical system by explicit functions. This methodology has been widely employed in many applications such as design optimization, response prediction and model validation. But so far the literature related to its application in structural damage identification (SDI) is scarce. Therefore this study attempts to present a systematic SDI procedure comprising four sequential steps of feature selection, parameter screening, primary response surface (RS) modeling and updating, and reference-state RS modeling with SDI realization using the factorial design (FD) and the central composite design (CCD). The last two steps imply the implementation of inverse problems by model updating in which the RS models substitute the FE models. The proposed method was verified against a numerical beam, a tested reinforced concrete (RC) frame and an experimental full-scale bridge with the modal frequency being the output responses. It was found that the proposed RSM-based method performs well in predicting the damage of both numerical and experimental structures having single and multiple damage scenarios. The screening capacity of the FD can provide quantitative estimation of the significance levels of updating parameters. Meanwhile, the second-order polynomial model established by the CCD provides adequate accuracy in expressing the dynamic behavior of a physical system

  17. Damage Effects Identified By Scatter Evaluation Of Supersmooth Surfaces

    Science.gov (United States)

    Stowell, W. K.

    1984-10-01

    The surface quality of optics used in an extremely sensitive laser instrument, such as a Ring Laser Gyro (RLG), is critical. This has led to the development of a Variable Angle Scatterometer at the Air Force Wright Aeronautical Laboratories at Wright-Patterson Air Force Base, which can detect low level light scatter from the high quality optics used in RLG's, without first overcoating with metals. With this instrument we have been able to identify damage effects that occur during the typical processing and handling of optics which cause wide variation in subsequent measurements depending on when, in the process, one takes data. These measurements indicate that techniques such as a Total Integrated Scatter (TIS) may be inadequate for standards on extremely low scatter optics because of the lack of sensitivity of the method on such surfaces. The general term for optical surfaces better than the lowest level of the scratch-dig standards has become "supersmooth", and is seen in technical literature as well as in advertising. A performance number, such as Bidirectional Radiation Distribution Function (BRDF), which can be measured from the uncoated optical surface by equipment such as the Variable Angle Scatterometer (VAS) is proposed as a method of generating better optical surface specifications. Data show that surfaces of average BRDF values near 10 parts per billion per steriadian (0.010 PPM/Sr) for 0-(301 = 0.5, are now possible and measurable.

  18. [Passive detection of aeroengine exhaust based on Fourier transform infrared system].

    Science.gov (United States)

    Li, Shao-cheng; Zuo, Hong-fu; Xia, Qing

    2008-10-01

    Since the composition and concentration of aeroengine exhaust can reflect the combustion efficiency, they can provide the basis for condition based maintenance, and also the basis for the analysis of environment pollution caused by aeroengine exhaust. So the importance of aeroengine exhaust detection is evident. Up to now, the measurement of aeroengine exhaust is based on sampling analysis which is not convenient and can't meet the detection requirements when an aeroplane is flying-off or flying in the sky. Hence, new methods of exhaust detection must be studied. The passive measurement technology based on Fourier transform infrared spectroscopy (FTIR) was applied to the measurement of aeroengine exhaust in the present paper. At first, the principle of passive measurement based on FTIR was introduced in detail. On this basis, a model algorithm for gas concentration calculation was deduced based on the principle of infrared transmission. Then the feasibility of aeroengine exhaust measurement based on passive FTIR was analyzed, and the passive measurement method of aeroengine exhaust based on FTIR was given. In the end, an experiment of aeroengine exhaust passive measurement was carried out by a FTIR with the type of Tensor 27 produced by BRUKER. Good quality spectra of the exhaust and the background were measured. Based on the model algo rithm of passive measurement, the absorbance spectra of CO and NO were obtained respectively, and the concentrations of CO and NO were figured out. To check up the veracity of this method, a comparison was made with another apparatus. There were only little differences between the results of the two experiments, showing that the passive measurement technology based on FTIR could meet the requirements of aeroengine exhaust detection.

  19. 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.

  20. Probing and repairing damaged surfaces with nanoparticle-containing microcapsules

    Science.gov (United States)

    Kratz, Katrina; Narasimhan, Amrit; Tangirala, Ravisubhash; Moon, Sungcheal; Revanur, Ravindra; Kundu, Santanu; Kim, Hyun Suk; Crosby, Alfred J.; Russell, Thomas P.; Emrick, Todd; Kolmakov, German; Balazs, Anna C.

    2012-02-01

    Nanoparticles have useful properties, but it is often important that they only start working after they are placed in a desired location. The encapsulation of nanoparticles allows their function to be preserved until they are released at a specific time or location, and this has been exploited in the development of self-healing materials and in applications such as drug delivery. Encapsulation has also been used to stabilize and control the release of substances, including flavours, fragrances and pesticides. We recently proposed a new technique for the repair of surfaces called `repair-and-go'. In this approach, a flexible microcapsule filled with a solution of nanoparticles rolls across a surface that has been damaged, stopping to repair any defects it encounters by releasing nanoparticles into them, then moving on to the next defect. Here, we experimentally demonstrate the repair-and-go approach using droplets of oil that are stabilized with a polymer surfactant and contain CdSe nanoparticles. We show that these microcapsules can find the cracks on a surface and selectively deliver the nanoparticle contents into the crack, before moving on to find the next crack. Although the microcapsules are too large to enter the cracks, their flexible walls allow them to probe and adhere temporarily to the interior of the cracks. The release of nanoparticles is made possible by the thin microcapsule wall (comparable to the diameter of the nanoparticles) and by the favourable (hydrophobic-hydrophobic) interactions between the nanoparticle and the cracked surface.

  1. A QUANTITATIVE DISCRETE ELEMENT MODEL TO INVESTIGATE SUB-SURFACE DAMAGE DUE TO SURFACE POLISHING

    OpenAIRE

    André, Damien; Iordanoff, Ivan; Charles, Jean-Luc; NÉAUPORT, Jérôme

    2012-01-01

    This work is a continuation of a previous study that investigated sub-surface damage in silica glass due to surface polishing. In this previous study, discrete element models have shown qualitatively good agreement with experiments. The presented work propose a model allowing quantitative results by focusing on the continuous part of the problem. Special attemption was given to the discrete element model of silica glass considered as perfectly isotropic, elastic and brittle. To validate this ...

  2. Aero-Engine Fault Diagnosis Using Improved Local Discriminant Bases and Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Jianwei Cui

    2014-01-01

    Full Text Available This paper presents an effective approach for aero-engine fault diagnosis with focus on rub-impact, through combination of improved local discriminant bases (LDB with support vector machine (SVM. The improved LDB algorithm, using both the normalized energy difference and the relative entropy as quantification measures, is applied to choose the optimal set of orthogonal subspaces for wavelet packet transform- (WPT- based signal decomposition. Then two optimal sets of orthogonal subspaces have been obtained and the energy features extracted from those subspaces appearing in both sets will be selected as input to a SVM classifier to diagnose aero-engine faults. Experiment studies conducted on an aero-engine rub-impact test system have verified the effectiveness of the proposed approach for classifying working conditions of aero-engines.

  3. Corin/Dorin: A WDM-Enabled Platform for Aero-Engine Control Systems

    OpenAIRE

    Xia, Ming; Moslehi, Behzad; Mukherjee, Biswanath; Behbahani, Alireza; Millar, Richard

    2008-01-01

    The Full Authority Digital Electronic Control (FADEC) centralized architecture has become the norm in aero-engine control systems. With a centralized system, changes are costly and complex [1]. The goal of this work is to develop the architectural design concept for a distributed supporting network called Coarse WDM Optical Ring Network (CORIN) appropriate for aero-engine performance monitoring. A CORIN features high bandwidth, reliability, modularity, scalability, flexibility, an...

  4. Fault Diagnosis of Demountable Disk-Drum Aero-Engine Rotor Using Customized Multiwavelet Method

    OpenAIRE

    Jinglong Chen; Yu Wang; Zhengjia He; Xiaodong Wang

    2015-01-01

    The demountable disk-drum aero-engine rotor is an important piece of equipment that greatly impacts the safe operation of aircraft. However, assembly looseness or crack fault has led to several unscheduled breakdowns and serious accidents. Thus, condition monitoring and fault diagnosis technique are required for identifying abnormal conditions. Customized ensemble multiwavelet method for aero-engine rotor condition identification, using measured vibration data, is developed in this paper. Fir...

  5. Wear and Fatigue of Railway Track Caused by Contamination, Sanding and Surface Damage

    OpenAIRE

    R.S. Dwyer-Joyce; Lewis, R; Gao, N.; Grieve, D.G.

    2003-01-01

    The wheel rail contact operates in an arduous environment. Damage to the surface of either component is possible during manufacture, installation, or operation. The question arises as to how tolerant is the railway wheel or section of track to surface indentation or damage. In this work a twin disc simulation has been used to relate the level of surface damage (as well as the way it is generated) to the fatigue life of the surfaces. A related problem is the presen...

  6. Super plastic forming technology applied to aeroengine and space equipment

    Science.gov (United States)

    Mandai, Katsumi

    1992-03-01

    Titanium alloys, especially Ti-6Al-4V, are widely used for the aeroengine and space equipment because of their high strength ratio and excellent resistance to heat and corrosion. But this material is difficult to manufacture by conventional plastic forming technology. It has been reported that Ti-6Al-4V shows extensive ductility (superplasticity), more than 1000 percent under the condition of both low straining rate and high temperature ranges. Superplastic forming technology applying this characteristic is widely known as one of the most cost-effective methods to save material. At the plant, gas argon blowing equipment for the superplastic forming technology has been developed and 'V2500 nose fairing' and 'fuel tank of the H-II rocket second stage reaction control system' have been manufactured. This paper describes the superplastic forming equipment and the two products above.

  7. 75 FR 45160 - SKF Aeroengine Falconer a Subsidiary of AB SKF Including On-Site Leased Workers From Manpower...

    Science.gov (United States)

    2010-08-02

    ..., Falconer, New York. The notice was published in the Federal Register on March 12, 2010 (75 FR 11924). At... Employment and Training Administration SKF Aeroengine Falconer a Subsidiary of AB SKF Including On-Site... February 4, 2010, applicable to workers of SKF Aeroengine Falconer, a subsidiary of AB SKF, including...

  8. Investigation Of Breakdown Induced Surface Damage On 805 Mhz Pillbox Cavity Interior Surfaces

    CERN Document Server

    Jana, M R; Leonova, M; Moretti, A; Tollestrup, A; Yonehara, K; Freemire, B; Torun, Y; Bowring, D; Flanagan, G

    2014-01-01

    The MuCool Test Area (MTA) at Fermilab is a facility to develop the technology required for ionization cooling for a future Muon Collider and/or Neutrino Factory. As part of this research program, we have tested two 805 MHz vacuum RF cavities in a multi-Tesla magnetic field to study the effects of the static magnetic field on the cavity operation. This study gives useful information on field emitters in the cavity, dark current, surface conditioning, breakdown mechanisms and material properties of the cavity. All these factors determine the maximum accelerating gradient in the cavity. This paper discusses the image processing technique for quantitative estimation of spark damage spot distribution on cavity interior surfaces. The distribution is compared with the electric field distribution predicted by a computer code calculation. The local spark density is proportional to probability of surface breakdown and shows a power law dependence on the maximum electric field (E). This E dependence is consistent with ...

  9. Fault Diagnosis of Demountable Disk-Drum Aero-Engine Rotor Using Customized Multiwavelet Method.

    Science.gov (United States)

    Chen, Jinglong; Wang, Yu; He, Zhengjia; Wang, Xiaodong

    2015-01-01

    The demountable disk-drum aero-engine rotor is an important piece of equipment that greatly impacts the safe operation of aircraft. However, assembly looseness or crack fault has led to several unscheduled breakdowns and serious accidents. Thus, condition monitoring and fault diagnosis technique are required for identifying abnormal conditions. Customized ensemble multiwavelet method for aero-engine rotor condition identification, using measured vibration data, is developed in this paper. First, customized multiwavelet basis function with strong adaptivity is constructed via symmetric multiwavelet lifting scheme. Then vibration signal is processed by customized ensemble multiwavelet transform. Next, normalized information entropy of multiwavelet decomposition coefficients is computed to directly reflect and evaluate the condition. The proposed approach is first applied to fault detection of an experimental aero-engine rotor. Finally, the proposed approach is used in an engineering application, where it successfully identified the crack fault of a demountable disk-drum aero-engine rotor. The results show that the proposed method possesses excellent performance in fault detection of aero-engine rotor. Moreover, the robustness of the multiwavelet method against noise is also tested and verified by simulation and field experiments. PMID:26512668

  10. Fault Diagnosis of Demountable Disk-Drum Aero-Engine Rotor Using Customized Multiwavelet Method

    Directory of Open Access Journals (Sweden)

    Jinglong Chen

    2015-10-01

    Full Text Available The demountable disk-drum aero-engine rotor is an important piece of equipment that greatly impacts the safe operation of aircraft. However, assembly looseness or crack fault has led to several unscheduled breakdowns and serious accidents. Thus, condition monitoring and fault diagnosis technique are required for identifying abnormal conditions. Customized ensemble multiwavelet method for aero-engine rotor condition identification, using measured vibration data, is developed in this paper. First, customized multiwavelet basis function with strong adaptivity is constructed via symmetric multiwavelet lifting scheme. Then vibration signal is processed by customized ensemble multiwavelet transform. Next, normalized information entropy of multiwavelet decomposition coefficients is computed to directly reflect and evaluate the condition. The proposed approach is first applied to fault detection of an experimental aero-engine rotor. Finally, the proposed approach is used in an engineering application, where it successfully identified the crack fault of a demountable disk-drum aero-engine rotor. The results show that the proposed method possesses excellent performance in fault detection of aero-engine rotor. Moreover, the robustness of the multiwavelet method against noise is also tested and verified by simulation and field experiments.

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

    International Nuclear Information System (INIS)

    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

  12. Reconstruction of near-surface tornado wind fields from forest damage

    OpenAIRE

    Beck, Veronika; Dotzek, Nikolai

    2010-01-01

    Tornado intensity is usually inferred from the damage produced. To foster postevent tornado intensity assessments, the authors present a model to reconstruct near-surface wind fields from forest damage patterns. By comparing the structure of observed and simulated damage patterns, essential parameters to describe a tornado near-surface wind field are derived, such as the ratio Gmax between circular and translational velocity, and the deflection angle a between peak wind and pressure gradient....

  13. Investigation of Surface Damage in Forming of High Strength and Galvanized Steel Sheets

    Institute of Scientific and Technical Information of China (English)

    Zhongqi Yu; Yingke Hou; Haomin Jiang; Xinping Chen; Weigang Zhang

    2009-01-01

    Powdering/exfoliating of coatings and scratching are the main forms of surface damage in the forming of galvanized steels and high strength steels (HSS), which result in increased die maintenance cost and scrap rate.In this study, a special rectangular box was developed to investigate the behavior and characteristics of surface damage in sheet metal forming (SMF) processes.U-channel forming tests were conducted to study the effect of tool hardness on surface damage in the forming of high strength steels and galvanized steels (hot-dip galvanized and galvannealed steels).Experimental results indicate that sheet deformation mode influences the severity of surface damage in SMF and surface damage occurs easily at the regions where sheet specimen deforms under the action of compressive stress.Die corner is the position where surface damage initiates.For HSS sheet, surface damage is of major interest due to high forming pressure.The HSS and hot-dip galvanized steels show improved ability of damage-resistance with increased hardness of the forming tool.However, for galvannealed steel it is not the forming tool with the highest hardness value that performs best.

  14. A Virtual Assembly System for Aero-engines Based on VR

    Institute of Scientific and Technical Information of China (English)

    GAO Ying; GUO Yun-peng; SHAO Ya-nan; XU Zhi-guo

    2008-01-01

    In this paper, a synthesized technique is explored through design of a virtual experiment system for main aeroengine based on VR, which attempts to integrate some VR techniques, such as 3D stereo simulation and modeling, 3D scene management and human-computer virtual assembly based on data glove and collision detection. The geometry modeling and instantiation technique, virtual hand modeling and data glove interaction technique are discussed chiefly. Finally, taking aim at assembling and dismantling experiment system of a certain aero-engine, interface technology is expounded also.

  15. Surface roughness and removal rate in magnetorheological finishing of a subsurface damage free surface

    Institute of Scientific and Technical Information of China (English)

    CHENG Haobo; WANG Yingwei; FENG Zhijing; CHENG Kai

    2005-01-01

    Based on computer-controlled optical surfacing, a new technique called magnetorheological finishing (MRF), is presented. The new technique combines the features of conventional loose abrasive machining with a wheel shaped polishing tool. The tool incorporates a host of features and has unprecedented fabricating versatility. The pre-polishing and fine polishing processes can be performed only by adjusting different parameters. The material removal function is studied theoretically and the results of simulation present a Gaussian distribution feature. Based on the established theoretical model, material removal rate experiments involving a parabolic mirror are designed and carried out to determine the effect of controllable parameters on size of the gap between the workpiece and the polishing wheel,rotating speed of the polishing wheel, concentration of volume fraction of non-magnetic particles and polishing time. Further experiments are carried out on the surface microstructure of the workpiece, the final surface roughness with an initial value of 10.98 nm reaches 1.22 nm root mean square (RMS) after 20 min of polishing. The subsurface damage experiment and the atomic force microscopy (AFM)measurement on the polished surface can also verify the feasibility of the MRF technique.

  16. Laser-induced damage initiated on the surface of particle contamination fused silica at 1064nm

    Energy Technology Data Exchange (ETDEWEB)

    Michlitsch, K.J.

    1998-06-01

    An experimental study was undertaken to quantify the effects of contamination particles on the damage threshold of laser-illuminated fused silica optics and set cleanliness requirements for optics on the beam line of the National Ignition Facility at Lawrence Livermore National Laboratory. Circular contamination particles were sputter-deposited onto fused silica windows which were then illuminated repetitively using a 1064nm laser. A variety of contaminants were tested including metals, oxides, and organics. Tests were conducted with particles on the input and output surfaces of the window, and the morphological features of the damage were very reproducible. A plasma often ignited at the contamination particle; its intensity was dependent upon the mass of the contaminant. Input surface damage was characteristically more severe than output surface damage. The size of the damaged area scaled with the size of the particle. On a few occasions, catastrophic damage (cracking or ablation of the substrate) initiated on the output surface due to contamination particles on either the input or output surface. From damage growth plots, predictions can be made about the severity of damage expected from contamination particles of known size and material.

  17. INVESTIGATION OF BREAKDOWN INDUCED SURFACE DAMAGE ON 805 MHZ PILLBOX CAVITY INTERIOR SURFACES

    Energy Technology Data Exchange (ETDEWEB)

    Jana, M. R.; Chung, M.; Leonova, M.; Moretti, A.; Tollestrup, A.; Yonehara, K.; Freemire, B.; Torun, Y.; Bowring, D.; Flanagan, G.

    2013-09-25

    The MuCool Test Area (MTA) at Fermilab is a facility to develop the technology required for ionization cooling for a future Muon Collider and/or Neutrino Factory. As part of this research program, we have tested two 805 MHz vacuum RF cavities in a multi-Tesla magnetic field to study the effects of the static magnetic field on the cavity operation. This study gives useful information on field emitters in the cavity, dark current, surface conditioning, breakdown mechanisms and material properties of the cavity. All these factors determine the maximum accelerating gradient in the cavity. This paper discusses the image processing technique for quantitative estimation of spark damage spot distribution on cavity interior surfaces. The distribution is compared with the electric field distribution predicted by a computer code calculation. The local spark density is proportional to probability of surface breakdown and shows a power law dependence on the maximum electric field (E). This E dependence is consistent with the dark current calculated from the Fowler-Nordheim equation.

  18. 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.

  19. Recognition and practice on remanufacturing engineering management of military aero-engines

    Institute of Scientific and Technical Information of China (English)

    Xiang Qiao

    2014-01-01

    The technologies of design, manufacture and MRO (maintenance, repair and overhaul) tor the mili- tary aero-engines, particularly for the fighters, are much more difficult to be mastered than those for any other aero-engines. They have been monopolized by only a few countries and the core technologies have never been transferred due to high risk, high investment, high barrier and high cost. Therefore, our country has long relied on mapping and copying the others' engines to satisfy the domestic demand due to not having our own indepen- dent technologies for the design and manufacture of military aero-engines. However, through over 20 years of unremitting effort, the independent MRO has been achieved for all the Chinese fighter engines, covering in- R&D (research and development) and in-service engines; and the MRO technologies, capabilities, quality, cost-efficiency have reached or exceeded those of original manufacturers. It has grown out of nothing, and then from weak to strong. In particular, dozens of projects concerning the R&D and engineering application of re- manufacturing have obtained the independent intellectual property rights and are playing an irreplaceable role in achieving leaping improvement of independent MRO for Chinese military aero-engines.

  20. RESEARCH AND DEVELOPMENT OF HIGH TEMPERATURE STRUCTURAL MATERIALS FOR AERO-ENGINE APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    G.Q. Zhang

    2005-01-01

    The status of research, development of superalloys and materials processing & fabrication technologies for aero-engine applications in China Aviation Industry, with an emphasis on recent achievements at BIAM including directionally solidified and single crystal superalloys for blade and vane applications, wrought superalloys for aero-engine disks and rings, and powder metallurgy (PM) superalloys for high performance disk applications were described. It was also reviewed the development of new class of high temperature structural materials, such as structural intermetallics, and advanced material processing technologies including rapid solidification,spray forming and so on. The trends of research and development of the above mentioned superalloys and processing technologies are outlined. Cast, wrought and PM superalloys are the workhorse materials for the hot section of current aero-engines. New high temperature materials and advanced processing technologies have been and will be the subject of study. It is speculated that high performance, high purity and low cost superalloys and technologies will play key roles in aero-engines.

  1. Laser annealing of plasma-damaged silicon surface

    Energy Technology Data Exchange (ETDEWEB)

    Sameshima, T., E-mail: tsamesim@cc.tuat.ac.jp [Tokyo University of Agriculture and Technology, Tokyo, 184-8588 (Japan); Hasumi, M. [Tokyo University of Agriculture and Technology, Tokyo, 184-8588 (Japan); Mizuno, T. [Kanagawa University, Kanagawa, 259-1293 (Japan)

    2015-05-01

    Highlights: • Ar plasma irradiation caused serious damage at SiO{sub 2}/Si interfaces. • The light induced minority carrier effective lifetime (τ{sub eff}) was decreased to 1.7 × 10{sup −5} s by Ar plasma irradiation. • The density of charge injection type interface traps at 9.1 × 10{sup 11} cm{sup −2} eV{sup −1} was formed. • 940-nm laser irradiation at 3.7 × 10{sup 4} W/cm{sup 2} for 4 × 10{sup −3} s cured the interface. • It increased τ{sub eff} to 1.7 × 10{sup −3} s and decreased D{sub it} to 2.1 × 10{sup 10} cm{sup −2} eV{sup −1}. - Abstract: 13.56 MHz capacitance coupled Ar plasma irradiation at 50 W for 120 s caused serious damage at SiO{sub 2}/Si interfaces for n-type 500-μm-thick silicon substrates. The 635-nm-light induced minority carrier effective lifetime (τ{sub eff}) was decreased from 1.7 × 10{sup −3} (initial) to 1.0 × 10{sup −5} s by Ar plasma irradiation. Moreover, the capacitance response at 1 MHz alternative voltage as a function of the bias voltage (C–V) was changed to hysteresis characteristic associated with the density of charge injection type interface traps at the mid gap (D{sub it}) at 9.1 × 10{sup 11} cm{sup −2} eV{sup −1}. Subsequent 940-nm laser annealing at 3.7 × 10{sup 4} W/cm{sup 2} for 4.0 × 10{sup −3} s markedly increased τ{sub eff} to 1.7 × 10{sup −3} s and decreased D{sub it} to 2.1 × 10{sup 10} cm{sup −2} eV{sup −1}. The hysteresis phenomenon was reduced in C–V characteristics. Laser annealing effectively decreased the density of plasma induced carrier recombination and trap states. However, laser annealing with a high power intensity of 4.0 × 10{sup 4} W/cm{sup 2} seriously caused a thermal damage associated with a low τ{sub eff} and a high D{sub it} with no hysteresis characteristic.

  2. Modeling study on the surface morphology evolution during removing the optics surface/subsurface damage using atmospheric pressure plasma processing

    Science.gov (United States)

    Xin, Qiang; Su, Xing; Wang, Bo

    2016-09-01

    Plasma processing has been widely reported as an effective tool in relieving or removing surface/subsurface damage induced by previous mechanical machining process. However, the surface morphology evolution during removing the damage using plasma processing is rarely reported. In this research, this procedure is studied based on experiments and robust numerical models developed on the basis of Level Set Method (LSM). Even if some unique properties of plasma etching are observed, such as particle redistribution, the dominant role of isotropic etching of plasma processing is verified based on experiments and 2D LSM simulations. With 2D LSM models, the damage removal process under various damage characteristics is explored in detail. Corresponding peak-to-valley roughness evolution is investigated as well. Study on morphology evolution is also conducted through the comparison between experiments and 3D LSM computations. The modeling results and experiments show good agreement with each other. The trends of simulated roughness evolution agree with the experiments as well. It is revealed that the plasma processing may end up with a planar surface depending on the damage characteristics. The planarization procedure can be divided into four parts: crack opening and pit formation; pit coalescing and shallow pits subsumed by deep ones; morphology duplicate etching; and finally a planar and damage free surface.

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

    International Nuclear Information System (INIS)

    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)

  4. Surface Characteristics and Damage Distributions of Diamond Wire Sawn Wafers for Silicon Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Sopori, Bhushan; Devayajanam, Srinivas; Basnyat, Prakash

    2016-06-12

    This paper describes surface characteristics, in terms of its morphology, roughness and near-surface damage of Si wafers cut by diamond wire sawing (DWS) of Si ingots under different cutting conditions. Diamond wire sawn Si wafers exhibit nearly-periodic surface features of different spatial wavelengths, which correspond to kinematics of various movements during wafering, such as ingot feed, wire reciprocation, and wire snap. The surface damage occurs in the form of frozen-in dislocations, phase changes, and microcracks. The in-depth damage was determined by conventional methods such as TEM, SEM and angle-polishing/defect-etching. However, because these methods only provide local information, we have also applied a new technique that determines average damage depth over a large area. This technique uses sequential measurement of the minority carrier lifetime after etching thin layers from the surfaces. The lateral spatial damage variations, which seem to be mainly related to wire reciprocation process, were observed by photoluminescence and minority carrier lifetime mapping. Our results show a strong correlation of damage depth on the diamond grit size and wire usage.

  5. Exogenous glycosaminoglycans coat damaged bladder surfaces in experimentally damaged mouse bladder

    OpenAIRE

    Hurst Robert E; Coffman Jean; Kyker Kimberly D

    2005-01-01

    Abstract Background Interstital cystitis is often treated with exogenous glycosaminoglycans such as heparin, chondroitin sulphate (Uracyst), hyaluronate (Cystistat) or the semi-synthetic pentosan polysulphate (Elmiron). The mechanism of action is presumed to be due to a coating of the bladder surface to replace the normally present chondroitin sulphate and heparan sulphate lost as a result of the disease. This study used fluorescent labelled chondroitin sulphate to track the distribution of g...

  6. Damage surfaces of cooper, niobium and titanium under micrometeorites impact

    Institute of Scientific and Technical Information of China (English)

    Nikitushkina; O.; N.

    2005-01-01

    Structure of near-crater regions of copper, niobium and titanium samples exposed in the outer space was studied. Flat Cu, Nb, Ti specimens 1 cm× 1 cm and 1 mm thickness were placed on the out-side surface of "MIR" space orbit station and exposed during 1.5 year. The samples than was studied by scanning electron microscopy with X-ray analysis.……

  7. Damage surfaces of cooper, niobium and titanium under micrometeorites impact

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ Structure of near-crater regions of copper, niobium and titanium samples exposed in the outer space was studied. Flat Cu, Nb, Ti specimens 1 cm× 1 cm and 1 mm thickness were placed on the out-side surface of "MIR" space orbit station and exposed during 1.5 year. The samples than was studied by scanning electron microscopy with X-ray analysis.

  8. Luminescence Investigation of SiO2 Surfaces Damaged by 0.35 mm Laser Illumination

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, M.; Battersby, C.L.; Demos, S.G.

    1999-12-15

    Following initiation at absorbing surface flaws, UV laser-induced damage to polished fused-silica surfaces continues to grow upon subsequent illumination. In this study photoluminescence spectroscopy was used to detect the formation of a modified, absorbing layer of silica that could be responsible for the continued growth of the damage site. For damage sites created with pulsed 355 nm illumination, three characteristic photoluminescence peaks are detected within the damage sites when excited with a 351 nm CW beam. Two of the peaks are likely due to the well-known E' and NBOHC defects associated with oxygen vacancies and broken Si-0 bonds, respectively. The third, and dominant, peak at 560 nm has not been clearly identified, but is likely associated with a change in stoichiometry of the silica. The relative intensities of the peaks are non-uniform across individual damage sites. The photoluminescence data is being combined with insights from various optical and electron microscopies to develop an understanding of laser-induced damage sites. The objective is to develop strategies to slow or stop the growth of the damage sites.

  9. Superhydrophobic antireflective silica films: fractal surfaces and laser-induced damage thresholds

    Science.gov (United States)

    Xu, Yao; Wu, Dong; Sun, Yu Han; Huang, Zu Xing; Jiang, Xiao Dong; Wei, Xiao Feng; Li, Zhi Hong; Zhong Dong, Bao; Wu, Zhong Hua

    2005-02-01

    Several superhydrophobic antireflective silica films have been prepared by a solgel method that uses hexamethyl-disilizane (HMDS) as a modifier. In a high-power laser, laser-induced damage thresholds (LIDTs) of 23-30 J/cm2 were obtained at 1064-nm wavelength with 1-ns pulse duration. By atomic-force microscopy and optical microscopy, the fractal surfaces of films were studied, and multifractal spectra (MFSs) were calculated both before and after laser damage. The two-sided effect of HMDS on particle growth determined the surface fractal of a particle and the multifractal structure of a film's surface. The bigger Deltaa was, both before and after laser damage, the lower the LIDT was. The effect of methyl groups should be included in the determination of the MFS of the LIDT.

  10. Relationship between subsurface damage and surface roughness of ground optical materials

    Institute of Scientific and Technical Information of China (English)

    LI Sheng-yi; WANG Zhuo; WU Yu-lie

    2007-01-01

    A theoretical model of relationship between subsurface damage and surface roughness was established to realize rapid and non-destructive measurement of subsurface damage of ground optical materials. Postulated condition of the model was that subsurface damage depth and peak-to-valley surface roughness are equal to depth of radial and lateral cracks in brittle surface induced by small-radius (radius≤200 μm) spherical indenter, respectively. And contribution of elastic stress field to the radial cracks propagation was also considered in the loading cycle. Subsurface damage depth of ground BK7 glasses was measured by magnetorheological finishing spot technique to validate theoretical ratio of subsurface damage to surface roughness. The results show that the ratio is directly proportional to load of abrasive grains and hardness of optical materials, while inversely proportional to granularity of abrasive grains and fracture toughness of optical materials. Moreover, the influence of the load and fracture toughness on the ratio is more significant than the granularity and hardness, respectively. The measured ratios of 80 grit and 120 grit fixed abrasive grinding of BK7 glasses are 5.8 and 5.4, respectively.

  11. Analytical Redundancy Design for Aeroengine Sensor Fault Diagnostics Based on SROS-ELM

    Directory of Open Access Journals (Sweden)

    Jun Zhou

    2016-01-01

    Full Text Available Analytical redundancy technique is of great importance to guarantee the reliability and safety of aircraft engine system. In this paper, a machine learning based aeroengine sensor analytical redundancy technique is developed and verified through hardware-in-the-loop (HIL simulation. The modified online sequential extreme learning machine, selective updating regularized online sequential extreme learning machine (SROS-ELM, is employed to train the model online and estimate sensor measurements. It selectively updates the output weights of neural networks according to the prediction accuracy and the norm of output weight vector, tackles the problems of singularity and ill-posedness by regularization, and adopts a dual activation function in the hidden nodes combing neural and wavelet theory to enhance prediction capability. The experimental results verify the good generalization performance of SROS-ELM and show that the developed analytical redundancy technique for aeroengine sensor fault diagnosis based on SROS-ELM is effective and feasible.

  12. COMPUTATION OF THE VIBRATION OF A WHOLE AERO-ENGINE MODEL WITH NONLINEAR BEARINGS

    OpenAIRE

    Hai Minh Pham

    2010-01-01

    Aero-engine assemblies are complex structures typically involving two or three nested rotors mounted within a flexible casing via squeeze-film damper (SFD) bearings. The deployment of SFDs into such structures is highly cost-effective but requires careful calculation since they can be highly nonlinear in their performance, particularly if they are unsupported (i.e. without a retainer spring). The direct study of whole-engine models with nonlinear bearings has been severely limited by the fa...

  13. Analytical Redundancy Design for Aeroengine Sensor Fault Diagnostics Based on SROS-ELM

    OpenAIRE

    Jun Zhou; Yuan Liu; Tianhong Zhang

    2016-01-01

    Analytical redundancy technique is of great importance to guarantee the reliability and safety of aircraft engine system. In this paper, a machine learning based aeroengine sensor analytical redundancy technique is developed and verified through hardware-in-the-loop (HIL) simulation. The modified online sequential extreme learning machine, selective updating regularized online sequential extreme learning machine (SROS-ELM), is employed to train the model online and estimate sensor measurement...

  14. 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.

  15. Laser damage of HR, AR-coatings, monolayers and bare surfaces at 1064 nm

    Science.gov (United States)

    Garnov, S. V.; Klimentov, S. M.; Said, A. A.; Soileau, M. J.

    1993-01-01

    Laser induced damage thresholds and morphologies were investigated in a variety of uncoated and coated surfaces, including monolayers and multi-layers of different chemical compositions. Both antireflective (AR) and highly reflective (HR) were tested. Testing was done at 1064 nm with 25 picosecond and 8 nanosecond YAG/Nd laser single pulses. Spot diameter in the experiments varied from 0.09 to 0.22 mm. The laser damage measurement procedure consisted of 1-on-1 (single laser pulse in the selected site) and N-on-1 experiments including repeated irradiation by pulses of the same fluence and subsequently raised from pulse to pulse fluence until damage occurred. The highest picosecond damage thresholds of commercially available coatings averaged 12 - 14 J/sq cm, 50 percent less than thresholds obtained in bare fused silica. Some coatings and bare surfaces revealed a palpable preconditioning effect (an increase in threshold of 1.2 to 1.8 times). Picosecond and nanosecond data were compared to draw conclusions about pulse width dependence. An attempt was made to classify damage morphologies according to the type of coating, class of irradiating, and damage level.

  16. Mode shape description of an aero-engine casing structure using Zernike moment descriptors

    Institute of Scientific and Technical Information of China (English)

    LIU Ying-chao; ZANG Chao-ping

    2011-01-01

    Vibration mode shape description of an aero-engine casing structure using Zernike moment descriptor (ZMD) was introduced in this paper. The mode shapes of the aero-engine casing structure can be decomposed as a linear combination of a series of Zernike polynomials, with the feature of each Zernike polynomial reflecting a part of characteristic of mode shapes, based on Zernike moment transformation. Meanwhile, the reconstruction of mode shapes with ZMD was explored and its ability to filtering the noise contaminated in the mode shapes was studied. Simulation of the aero-engine casing structure indicated the advantage of this method to depict the mode shapes of a symmetric structure. Results demonstrate that the Zernike moment description of the mode shapes can effectively describe the double modes in the symmetric structure and also has the ability to remove or significantly reduce the influence of noise in the mode shapes. Such feature shows great practical value for further research on the correlation, model updating and model validation of the symmetric structure's finite element model.

  17. Recognition and practice on remanufacturing engineering management of military aero-engines

    Institute of Scientific and Technical Information of China (English)

    Xiang Qiao

    2014-01-01

    The technologies of design,manufacture and MRO (maintenance,repair and overhaul) for the mili-tary aero-engines,particularly for the fighters,are much more difficult to be mastered than those for any other aero-engines. They have been monopolized by only a few countries and the core technologies have never been transferred due to high risk,high investment,high barrier and high cost. Therefore,our country has long relied on mapping and copying the others’engines to satisfy the domestic demand due to not having our own indepen-dent technologies for the design and manufacture of military aero-engines. However,through over 20 years of unremitting effort,the independent MRO has been achieved for all the Chinese fighter engines,covering in-R&D (research and development) and in-service engines;and the MRO technologies,capabilities,quality, cost-efficiency have reached or exceeded those of original manufacturers. It has grown out of nothing,and then from weak to strong. In particular,dozens of projects concerning the R&D and engineering application of re-manufacturing have obtained the independent intellectual property rights and are playing an irreplaceable role in achieving leaping improvement of independent MRO for Chinese military aero-engines.

  18. The Brief Introduction of Different Laser Diagnostics Methods Used in Aeroengine Combustion Research

    Directory of Open Access Journals (Sweden)

    Fei Xing

    2016-01-01

    Full Text Available Combustion test diagnosis has always been one of the most important technologies for the development of aerospace engineering. The traditional methods of measurement have been unable to meet the requirements of accurate capture of the flow field in the development process of the aeroengine combustor. Therefore, the development of high-precision measurement and diagnostic techniques to meet the needs of the aeroengine combustor design is imperative. Laser diagnostics techniques developed quickly in the past several years. They are used to measure the parameters of the combustion flow field such as velocity, temperature, and components concentration with high space and time resolution and brought no disturbance. Planar laser-induced fluorescence, coherent anti-Stokes Raman scattering, tunable diode laser absorption spectroscopy, and Raman scattering were introduced systemically in this paper. After analysis of their own advantages and disadvantages, the authors considered validated Raman scattering system and Tunable Diode Laser Absorption Tomography are more suitable for research activities on aeroengine combustion systems.

  19. Oxygen plasma damage to blanket and patterned ultralow-κ surfaces

    International Nuclear Information System (INIS)

    Oxygen plasma damage to blanket and patterned ultralow-κ (ULK) dielectric surfaces was investigated by examining the effect of plasma species and dielectric materials. Blanket ULK films and patterned structures were treated by O2 plasma in a remote plasma chamber where the ions and radicals from the plasma source can be separately controlled to study their respective roles in the damage process. The plasma damage was characterized by angle resolved x-ray photoelectron spectroscopy, x-ray reflectivity, and Fourier transform infrared spectroscopy. Studies of the angle dependence of oxygen plasma damage to blanket ULK films indicated that damage by ions was anisotropic while that by radicals was isotropic. Ions were found to play an important role in assisting carbon depletion by oxygen radicals on the blanket film surface. More plasma damage was observed with increasing porosity in ultralow-κ films. Probable reaction paths were proposed by analyzing the reaction by-products. Plasma damage to the sidewall of low-κ trenches was examined by electron energy loss (EELS) analysis. The depletion depth of carbon was found to be related to the penetration of radical species into the porous dielectric and the distribution at the sidewall and trench bottom was affected by the trench pattern geometry, i.e., the aspect ratio, which can be correlated with the electron potential distribution and subsequent trajectory of ions. Vapor silylation was applied for dielectric recovery of trench structure and the result was examined by EELS. The trimethylchlorosilane was found to be effective for recovery of the sidewall carbon loss. The recovery was better for loss induced by radical O2 than by hybrid O2 and the difference was attributed to the surface densification by ions limiting the mass transport of vapor chemicals.

  20. 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.

  1. HF-based etching processes for improving laser damage resistance of fused silica optical surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Suratwala, T I; Miller, P E; Bude, J D; Steele, R A; Shen, N; Monticelli, M V; Feit, M D; Laurence, T A; Norton, M A; Carr, C W; Wong, L L

    2010-02-23

    The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF or NH{sub 4}F:HF at various ratios and concentrations) under different process conditions (e.g., agitation frequencies, etch times, rinse conditions, and environmental cleanliness). Subsequently, the laser damage resistance (at 351 or 355 nm) of the treated surface was measured. The laser damage resistance was found to be strongly process dependent and scaled inversely with scratch width. The etching process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation. The redeposit precursor was reduced (and hence the damage threshold was increased) by: (1) increasing the SiF{sub 6}{sup 2-} solubility through reduction in the NH4F concentration and impurity cation impurities, and (2) improving the mass transport of reaction product (SiF{sub 6}{sup 2-}) (using high frequency ultrasonic agitation and excessive spray rinsing) away from the etched surface. A 2D finite element crack-etching and rinsing mass transport model (incorporating diffusion and advection) was used to predict reaction product concentration. The predictions are consistent with the experimentally observed process trends. The laser damage thresholds also increased with etched amount (up to {approx}30 {micro}m), which has been attributed to: (1) etching through lateral cracks where there is poor acid penetration, and (2) increasing the crack opening resulting in increased mass transport rates. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for 30 {micro}m wide scratches increased from 7 to 41 J/cm{sup 2}, and the statistical

  2. Surface damage characteristics of CFC and tungsten with repetitive ELM-like pulsed plasma irradiation

    Science.gov (United States)

    Kikuchi, Y.; Nishijima, D.; Nakatsuka, M.; Ando, K.; Higashi, T.; Ueno, Y.; Ishihara, M.; Shoda, K.; Nagata, M.; Kawai, T.; Ueda, Y.; Fukumoto, N.; Doerner, R. P.

    2011-08-01

    Surface damage of carbon fiber composite (CFC) and tungsten (W) due to repetitive ELM-like pulsed plasma irradiation has been investigated by using a magnetized coaxial plasma gun. CX2002U CFC and stress-relieved W samples were exposed to repetitive pulsed deuterium plasmas with duration of ˜0.5 ms, incident ion energy of ˜30 eV, and surface absorbed energy density of ˜0.3-0.7 MJ/m2. Bright spots on a CFC surface during pulsed plasma exposures were clearly observed with a high-speed camera, indicating a local surface heating. No melting of a W surface was observed under a single plasma pulse exposure at energy density of ˜0.7 MJ/m2, although cracks were formed. Cracking of the W surface grew with repetitive pulsed plasma exposures. Subsequently, the surface melted due to localized heat absorption.

  3. In situ ultrasonic surface wave assesment of fatigue damage accumulation in AL 6061

    International Nuclear Information System (INIS)

    This work investigated in situ characterization of room temperature fatigue damage in Al6061 material using an ultrasonic surface wave technique. The goal of the work was to show that an in situ surface wave technique would provide valuable information concerning fatigue damage initiation and accumulated process in Al6061 material of aircraft application. Two kinds of plate specimen were made for this study. The specimens were at least 160 mm in length to accommodate the ultrasonic surface wave transducer with 2 or 4 MHz frequency, while the specimen is held in the grips of MTS hydraulic fatigue test machine. Once the transducer were in place, ultrasonic data was recorded by both digital ultrasonic flaw detecter(USD10) and computer before the fatigue tests were started. The fatigue tests were then started and the specimen were cycled to the desired number of cycles and finally to the fracture of specimen. The ultrasonic data were recorded for two kinds of applied stress level with the some stress ratio(R=0.01). It was found clearly that the velocity and attenuation of ultrasonic surface wave were changed due to the number of fatigue cycle as well as the change of applied stress levels. From the results, the applicability of in situ ultrasonic surface wave technique to evaluate successive change of fatigue damage of Al6061 was discussed in more details.

  4. DNA damage response to different surface chemistry of silver nanoparticles in mammalian cells

    International Nuclear Information System (INIS)

    Silver nanoparticles (Ag NPs) have recently received much attention for their possible applications in biotechnology and life sciences. Ag NPs are of interest to defense and engineering programs for new material applications as well as for commercial purposes as an antimicrobial. However, little is known about the genotoxicity of Ag NPs following exposure to mammalian cells. This study was undertaken to examine the DNA damage response to polysaccharide surface functionalized (coated) and non-functionalized (uncoated) Ag NPs in two types of mammalian cells; mouse embryonic stem (mES) cells and mouse embryonic fibroblasts (MEF). Both types of Ag NPs up-regulated the cell cycle checkpoint protein p53 and DNA damage repair proteins Rad51 and phosphorylated-H2AX expression. Furthermore both of them induced cell death as measured by the annexin V protein expression and MTT assay. Our observations also suggested that the different surface chemistry of Ag NPs induce different DNA damage response: coated Ag NPs exhibited more severe damage than uncoated Ag NPs. The results suggest that polysaccharide coated particles are more individually distributed while agglomeration of the uncoated particles limits the surface area availability and access to membrane bound organelles

  5. Localized CO2 laser treatment and post-heating process to reduce the growth coefficient of fused silica surface damage

    Institute of Scientific and Technical Information of China (English)

    Shizhen Xu; Xiaotao Zu; Xiaodong Yuan

    2011-01-01

    The lifetime of optical components in high-fluence ultraviolet (UV) laser applications is typically limited by laser-initiated damage and its subsequent growth. Using 10.6-μm CO2 laser pulses, we successfully mitigate 355-nm laser induced damage sites on fused silica surface with dimensions less than 200 μm.The damage threshold increases and the damage growth mitigates. However, the growth coefficients of new damage on the CO2 laser processed area are higher than those of the original sample. The damage grows with crack propagation for residual stress after CO2 laser irradiation. Furthermore, post-heating is beneficial to the release of residual stress and slows down the damage growth.%@@ The lifetime of optical components in high-fluence ultraviolet (UV) laser applications is typically limited by laser-initiated damage and its subsequent growth.Using 10.6-μm CO2 laser pulses, we successfully mitigate 355-nm laser induced damage sites on fused silica surface with dimensions less than 200 μm.The damage threshold increases and the damage growth mitigates.However, the growth coefficients of new damage on the CO2 laser processed area are higher than those of the original sample.The damage grows with crack propagation for residual stress after CO2 laser irradiation.Furthermore, post-heating is beneficial to the release of residual stress and slows down the damage growth.

  6. Surface and subsurface damage detection in cement-based materials using electrical resistance tomography

    Science.gov (United States)

    Ruan, T.; Poursaee, A.

    2016-04-01

    Cement-based materials are widely used in infrastructure facilities. However, often the degradation of structures leads to the failures earlier than designed service life. Thus, non-destructive testing techniques are urgently needed to evaluate the health information of the structures. In this paper, the implementation of Electrical Resistance Tomography (ERT) was investigated. This low cost, radiation free and easy to perform modality is based on measuring the electrical properties of the material under test and using that to evaluate the existence of defects in that material. It uses a set of boundary potentials and injected current to reconstruct the conductivity distribution. An automatic measurement system was developed and surface damages as well as subsurface damages on mortar specimens were investigated. The reconstructed images were capable to show the presence and the location of the damages.

  7. Low-damage surface smoothing of laser crystallized polycrystalline silicon using gas cluster ion beam

    International Nuclear Information System (INIS)

    Surface smoothing of laser crystallized polycrystalline silicon (poly-Si) films using gas cluster ion beam (GCIB) technology has been studied. It is found that both SF6-GCIB and O2-GCIB decrease the height of hillocks and reduce the surface roughness of the irradiated films. The mean surface roughness value of poly-Si films was reduced from 10.8 nm to 2.8 nm by SF6-GCIB irradiation at 80o. Ultraviolet reflectance measurement reveals that GCIB irradiation causes damage near-surface of the poly-Si films. Formation of the damage, however, can be suppressed by using GCIB irradiation at high incident angle. Effect of GCIB irradiation in a metal-insulator-semiconductor (MIS) capacitor has also been investigated. The capacitance-voltage curves of MIS capacitor with SF6-GCIB irradiation are distorted. On the contrary, the distortion is reduced by O2-GCIB irradiation at 80, which suggests that electrical-activated damage of the films can be decreased by using O2-GCIB irradiation

  8. Low-damage surface smoothing of laser crystallized polycrystalline silicon using gas cluster ion beam

    Science.gov (United States)

    Tokioka, H.; Yamarin, H.; Fujino, T.; Inoue, M.; Seki, T.; Matsuo, J.

    2007-04-01

    Surface smoothing of laser crystallized polycrystalline silicon (poly-Si) films using gas cluster ion beam (GCIB) technology has been studied. It is found that both SF6-GCIB and O2-GCIB decrease the height of hillocks and reduce the surface roughness of the irradiated films. The mean surface roughness value of poly-Si films was reduced from 10.8 nm to 2.8 nm by SF6-GCIB irradiation at 80°. Ultraviolet reflectance measurement reveals that GCIB irradiation causes damage near-surface of the poly-Si films. Formation of the damage, however, can be suppressed by using GCIB irradiation at high incident angle. Effect of GCIB irradiation in a metal-insulator-semiconductor (MIS) capacitor has also been investigated. The capacitance-voltage curves of MIS capacitor with SF6-GCIB irradiation are distorted. On the contrary, the distortion is reduced by O2-GCIB irradiation at 80, which suggests that electrical-activated damage of the films can be decreased by using O2-GCIB irradiation.

  9. Effects of cyclic stress and temperature on oxidation damage of a nickel-based superalloy

    International Nuclear Information System (INIS)

    Highlights: → FIB shows the formation of surface oxide scales and internal micro-voids. → Oxidation damage at 800 deg. C is much more severe than that at 700 deg. C and 750 deg. C. → Cyclic stress enhances the extent of oxidation damage at 750 deg. C and above. → Enrichment of Cr and Ti, as well as lower Ni and Co levels, in the surface oxides. → Penetration of oxygen into the material and internal oxidation are evidenced. - Abstract: Oxidation damage, combined with fatigue, is a concern for nickel-based superalloys utilised as disc rotors in high pressure compressor and turbine of aero-engines. A study has been carried out for a nickel-based alloy RR1000, which includes cyclic experiments at selected temperatures (700-800 deg. C) and microscopy examination using focused ion beam (FIB). The results suggest that the major mechanism of oxidation damage consists of the formation of surface oxide scales and internal micro-voids and oxide particles beneath the oxide scales, which become more severe with the increase of temperature. Applying a cyclic stress does not change the nature of oxidation damage but tends to enhance the extent of oxidation damage for temperatures at 750 deg. C and 800 deg. C. The influence of cyclic stress on oxidation damage appears to be insignificant at 700 deg. C, indicating a combined effect of cyclic stress and temperature. Further energy-dispersive X-ray spectrometry (EDXS) analyses show the enrichment of Cr and Ti, together with lower Ni and Co levels, in the surface oxide scales, suggesting the formation of brittle Cr2O3, TiO2, NiO and Co3O4 oxides on the specimen surface. Penetration of oxygen into the material and associated internal oxidation, which leads to further material embrittlement and associated failure, are evidenced from both secondary ion imaging and EDXS analyses.

  10. Evaluation of the surface damage to stainless steel caused by a micro-jet in seawater

    Science.gov (United States)

    Chong, Sang-Ok; Kim, Seong-Jong; Jeong, Jae-Yong

    2016-01-01

    As high-speed machines have been developed in marine and offshore industry cavitation damage due to the high speed of rotation of a fluid has been gradually increasing. The damage on the material's surface is a combination of electrochemical corrosion due to the passivity of the films being destroyed by Cl- and cavitation erosion due to the collapse of cavity bubbles. Hence, in this paper, the damage mechanisms for electrochemical corrosion and physical pressure for 415 stainless-steel cavities were evaluated in seawater solutions. The experiments included a galvanostatic experiment in a cavitation environment and a cavitation test with an ultrasonic amplitude of 30 µm at various times. The complex damage behaviors were compared and analyzed by scanning electron microscope (SEM) and 3D microscopy after completion of the experiment. As a result of the galvanostatic experiment under a cavitation condition in seawater, damage under a cavitation condition owing to the water cavitation peening effect was relatively less compared to that under a static condition.

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

    International Nuclear Information System (INIS)

    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. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  12. 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

  13. Surface damage through grazing incidence ions investigated by scanning tunneling microscopy

    International Nuclear Information System (INIS)

    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

  14. Model parameters estimation of aero-engine based on hybrid optimization algorithm%Model parameters estimation of aero-engine based on hybrid optimization algorithm

    Institute of Scientific and Technical Information of China (English)

    LI Qiu-hong; LI Ye-bo; JIANG Dian-wen

    2011-01-01

    A hybrid optimization algorithm for the time-domain identification of multivariable,state space model for aero-engine was presented in this paper.The optimization procedure runs particle swarm optimization(PSO) and least squares optimization(LSO) "in series".PSO starts from an initial population and searches for the optimum solution by updating generations.However,it can sometimes run into a suboptimal solution.Then LSO can start from the suboptimal solution of PSO,and get an optimum solution by conjugate gradient algorithm.The algorithm is suitable for the high-order multivariable system which has many parameters to be estimated in wide ranges.Hybrid optimization algorithm is applied to estimate the parameters of a 4-input 4-output state variable model(SVM) for aero-engine.The simulation results demonstrate the effectiveness of the proposed algorithm.

  15. Bilirubin influence on oxidative lung damage and surfactant surface tension properties

    OpenAIRE

    Dani C.; Martelli E.; Tronchin M.; Buonocore G.; Longini M.; Di Filippo A; Giossi M.; Rubaltelli F.F.

    2004-01-01

    To study the hypothesis that hyperbilirubinemia might reduce in vivo oxidative lung damage while also diminishing lung surfactant surface tension properties during acute lung injury, we performed a randomized study in a rabbit model of acute lung injury. Twenty rabbits were randomized to receive bilirubin or saline intravenously. Acute lung injury was induced by lung lavages with saline. Lung tissue oxidation was evaluated by measuring total hydroperoxide (TH), advanced oxidation protein prod...

  16. Electron trapping and detrapping in ion-beam-damaged diamond surfaces

    International Nuclear Information System (INIS)

    Ion-beam-damaged diamond surfaces subjected to electron irradiation are observed to develop a pronounced negative surface charge. In this study, this effect is shown to be associated with the capture of electrons into traps created by the ion irradiation process. The trapped charge increases with ion dose and incident electron current, and decreases with increasing sample temperature and laser illumination as the traps are depleted of charge. An activation energy for detrapping of about 1.5 eV is deduced from the temperature dependence of the charging

  17. An integration system for investment casting mould design of aeroengine turbine blade

    Institute of Scientific and Technical Information of China (English)

    Jiang Ruisong; Zhang Dinghua; Wang Wenhu; Shi Huajie

    2008-01-01

    An integration system was developed to satisfy the need of information integration in the process of designing,investment casting and monitoring aero-engine's turbo blade.The general architecture is detailed presented in this paper.The system mainly comprises of product master model,design information management,anti-deformation design of mould cavity,intelligence mould design and blade testing.The developed system can manage mould design and blade test data flow,optimize mould design process and achieve the goal of integration design.

  18. A feasibility study of a 3-D finite element solution scheme for aeroengine duct acoustics

    Science.gov (United States)

    Abrahamson, A. L.

    1980-01-01

    The advantage from development of a 3-D model of aeroengine duct acoustics is the ability to analyze axial and circumferential liner segmentation simultaneously. The feasibility of a 3-D duct acoustics model was investigated using Galerkin or least squares element formulations combined with Gaussian elimination, successive over-relaxation, or conjugate gradient solution algorithms on conventional scalar computers and on a vector machine. A least squares element formulation combined with a conjugate gradient solver on a CDC Star vector computer initially appeared to have great promise, but severe difficulties were encountered with matrix ill-conditioning. These difficulties in conditioning rendered this technique impractical for realistic problems.

  19. An analysis of the generation of subharmonics in aeroengine ducts and methods of their prevention

    Science.gov (United States)

    Vaidya, P. G.; Wang, K. S.

    1976-01-01

    When the fans of aero-engine ducts go supersonic they often produce radiation at the subharmonics of blade passage frequency known as Multiple Pure Tones. It has been shown that the conventional explanation that these MPTs are created by the shock waves is inadequate. An alternative mechanism based on the concept of 'strong interaction' between the harmonics during resonance is proposed. Expression for the governing equation for such an interaction is derived. The results show an improved agreement with observed data. The analysis has also led to several practical suggestions for the suppression of noise.

  20. Laser-induced damage of fused silica at 355 and 1065 nm initiated at aluminum contamination particles on the surface

    Energy Technology Data Exchange (ETDEWEB)

    Genin, F.Y.; Michlitsch, K.; Furr, J.; Kozlowski, M.R.; Krulevitch, P.

    1997-01-01

    1-{mu}m thick circular dots, 10-250 {mu}m dia, were deposited onto 1.14 cm thick fused silica windows by sputtering Al through a mask. Al shavings were also deposited on the windows to investigate effects of particle-substrate adhesion. The silica windows were then illuminated repetitively using a 3-ns, 355 nm and an 8.6-ns, 1064 nm laser. The tests were conducted at near normal incidence with particles on input and output surfaces of the windows. During the first shot, a plasma ignited at the metal particle and damage initiated on the fused silica surface. The morphology of the damage at the metal dots were reproducible but different for input and output surface contamination. For input surface contamination, minor damage occurred where the particle was located; such damage ceased to grow with the removal of contaminant material. More serious damage (pits and cracks) was initiated on the output surface (especially at 355 nm) and grew to catastrophic proportions after few shots. Output surface contaminants were usually ejected on the initial shot, leaving a wave pattern on the surface. No further damage occurred with subsequent shots unless a shot (usually the first shot) cracked the surface; such behavior was mostly observed at 355 nm and occasionally for large shavings at 1064 nm. The size of the damaged area scaled with the size of the particle (except when catastrophic damage occurred). Onset of catastrophic damage on output surface occurred only when particles exceeded a critical size. Damage behavior of the sputtered dots was found to be qualitatively similar to that of the shavings. The artificial contamination technique accelerated the study by allowing better control of the test conditions.

  1. Laser-induced damage of fused silica at 355 and 1065 nm initiated at aluminum contamination particles on the surface

    International Nuclear Information System (INIS)

    1-μm thick circular dots, 10-250 μm dia, were deposited onto 1.14 cm thick fused silica windows by sputtering Al through a mask. Al shavings were also deposited on the windows to investigate effects of particle-substrate adhesion. The silica windows were then illuminated repetitively using a 3-ns, 355 nm and an 8.6-ns, 1064 nm laser. The tests were conducted at near normal incidence with particles on input and output surfaces of the windows. During the first shot, a plasma ignited at the metal particle and damage initiated on the fused silica surface. The morphology of the damage at the metal dots were reproducible but different for input and output surface contamination. For input surface contamination, minor damage occurred where the particle was located; such damage ceased to grow with the removal of contaminant material. More serious damage (pits and cracks) was initiated on the output surface (especially at 355 nm) and grew to catastrophic proportions after few shots. Output surface contaminants were usually ejected on the initial shot, leaving a wave pattern on the surface. No further damage occurred with subsequent shots unless a shot (usually the first shot) cracked the surface; such behavior was mostly observed at 355 nm and occasionally for large shavings at 1064 nm. The size of the damaged area scaled with the size of the particle (except when catastrophic damage occurred). Onset of catastrophic damage on output surface occurred only when particles exceeded a critical size. Damage behavior of the sputtered dots was found to be qualitatively similar to that of the shavings. The artificial contamination technique accelerated the study by allowing better control of the test conditions

  2. CO/sub 2/-laser polishing of fused silica surfaces for increased laser damage resistance at 1. 06. mu. m

    Energy Technology Data Exchange (ETDEWEB)

    Temple, P.A.; Milam, D.; Lowdermilk, W.H.

    1980-04-03

    Bare fused silica surfaces were prepared by subjecting the mechanically polished surface to a rastered cw CO/sub 2/ laser beam. Analysis shows that this processing causes: (a) removal of a uniform layer of fused silica; and (b) a probable re-fusing or healing of existing subsurface fractures. The fused silica removal rate is found to be a function of the laser intensity and scan rate. These surfaces are seen to have very low scatter and to be very smooth. In addition, they have exhibited entrance surface damage thresholds at 1.06 ..mu..m, and 1 nsec, which are substantially above those seen on the mechanically polished surface. When damage does occur, it tends to be at a few isolated points rather than the general uniform damage seen on the mechanicaly polished part. In addition to the damage results, we will discuss an observational technique used for viewing these surfaces which employs dark-field illumination.

  3. CO2-laser polishing of fused silica surfaces for increased laser damage resistance at 1.06 μm

    International Nuclear Information System (INIS)

    Bare fused silica surfaces were prepared by subjecting the mechanically polished surface to a rastered cw CO2 laser beam. Analysis shows that this processing causes: (a) removal of a uniform layer of fused silica; and (b) a probable re-fusing or healing of existing subsurface fractures. The fused silica removal rate is found to be a function of the laser intensity and scan rate. These surfaces are seen to have very low scatter and to be very smooth. In addition, they have exhibited entrance surface damage thresholds at 1.06 μm, and 1 nsec, which are substantially above those seen on the mechanically polished surface. When damage does occur, it tends to be at a few isolated points rather than the general uniform damage seen on the mechanicaly polished part. In addition to the damage results, we will discuss an observational technique used for viewing these surfaces which employs dark-field illumination

  4. Femtosecond laser surface ablation of transparent solids: understanding the bulk filamentation damage

    Science.gov (United States)

    Kudryashov, Sergey I.; Joglekar, A.; Mourou, G.; Ionin, A. A.; Zvorykin, V. D.; Hunt, A. J.

    2007-06-01

    Direct SEM examination reveals a complex nanoscale structure of deep narrow central channels within shallow wide external craters produced by single-shot high-intensity femtosecond laser radiation on Corning 0211 glass and sapphire surfaces. These internal narrow channels are not expected from ordinary surface melt spallation and expulsion processes characteristic of the external surface nanocraters, but exhibit nearly the same appearance threshold. Surprisingly, the nanochannel radiuses rapidly saturate versus incident laser intensity indicating bulk rather than surface character of laser energy deposition, in contrast to the external craters extending versus laser intensity in a regular manner. These facts may be explained by channeling of electromagnetic radiation by near-surface ablative filamentary propagation of intense femtosecond laser pulses in the highly electronically excited dielectrics, by spherical aberrations in the surface layer, or deep drilling of the samples by short-wavelength Bremsstrahlung radiation of relatively hot surface electron-hole or electron-ion plasma. The double structure of ablated surface nano-features is consistent with similar structures observed for bulk damage features fabricated by femtosecond laser pulses at supercritical laser powers, but much lower laser intensities.

  5. Laser damage initiation and growth of antireflection coated S-FAP crystal surfaces prepared by pitch lap and magnetorheological finishing

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, C J; Menapace, J A; Schaffers, K I; Bibeau, C; Thomas, M D; Griffin, A J

    2005-10-31

    Antireflection (AR) coatings typically damage at the interface between the substrate and coating. Therefore the substrate finishing technology can have an impact on the laser resistance of the coating. For this study, AR coatings were deposited on Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] crystals that received a final polish by both conventional pitch lap finishing as well as magnetorheological finishing (MRF). SEM images of the damage morphology reveals laser damage originates at scratches and at substrate coating interfacial absorbing defects. Previous damage stability tests on multilayer mirror coatings and bare surfaces revealed damage growth can occur at fluences below the initiation fluence. The results from this study suggest the opposite trend for AR coatings. Investigation of unstable HR and uncoated surface damage morphologies reveals significant radial cracking that is not apparent with AR damage due to AR delamination from the coated surface with few apparent cracks at the damage boundary. Damage stability tests show that coated Yb:S-FAP crystals can operate at 1057 nm at fluences around 20 J/cm{sup 2} at 10 ns; almost twice the initiation damage threshold.

  6. Surface damage of metallic implants due to mechanical loading and chemical reactions

    Science.gov (United States)

    Ryu, Jaejoong

    The present study investigates interfacial damage mechanism of modular implants due to synergetic action of mechanical contact loading and corrosion. Modular implants are manufactured such that surfaces have a characteristic degree of roughness determined by tool tip size and motion of tool path or feeding speed. The central hypothesis for this work is that during contact loading of metallic implants, mechanisms of damage and dissolution are determined by contact loads, plastic deformation, residual stresses and environmental conditions at the nanoscale surface asperities; while during subsequent rest periods, mechanism of metallic dissolution is determined by the environmental conditions and residual stress field induced due to long range elastic interactions of the plastically deformed asperities. First part of the thesis is focused on investigating the mechanisms underlying surface roughness evolution due to stress-assisted dissolution during the rest period. The latter part is focused on investigating material removal mechanisms during single asperity contact of implant surfaces. Experimental study was performed to elucidate the roughness evolution mechanism by combined effect of multi-asperity contact and environmental corrosion. Cobalt-chromium-molybdenum specimen was subjected to either contact loading alone or alternating contact loading and exposure to reactive environment. Roughness of the specimen surface was monitored by optical profilometry and Fast Fourier Transform (FFT) calculation was used to characterize the evolving behavior of roughness modes. Finite element analysis (FEA) was employed to identify influences of surface morphological configurations and contact pressures on the residual stress development. Analytical model of multi-asperity contact has been developed for prediction of residual stress field for different roughness configurations during varying magnitude of contact loads based on elastic inclusion theory. Experimental results

  7. 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

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

    Science.gov (United States)

    Carr; Jeffrey W.

    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.

  9. The Chaotic Prediction for Aero-Engine Performance Parameters Based on Nonlinear PLS Regression

    Directory of Open Access Journals (Sweden)

    Chunxiao Zhang

    2012-01-01

    Full Text Available The prediction of the aero-engine performance parameters is very important for aero-engine condition monitoring and fault diagnosis. In this paper, the chaotic phase space of engine exhaust temperature (EGT time series which come from actual air-borne ACARS data is reconstructed through selecting some suitable nearby points. The partial least square (PLS based on the cubic spline function or the kernel function transformation is adopted to obtain chaotic predictive function of EGT series. The experiment results indicate that the proposed PLS chaotic prediction algorithm based on biweight kernel function transformation has significant advantage in overcoming multicollinearity of the independent variables and solve the stability of regression model. Our predictive NMSE is 16.5 percent less than that of the traditional linear least squares (OLS method and 10.38 percent less than that of the linear PLS approach. At the same time, the forecast error is less than that of nonlinear PLS algorithm through bootstrap test screening.

  10. Vibration Analysis of Aeroengine Blisk Structure Based on a Prestressed CMS Super-Element Method

    Directory of Open Access Journals (Sweden)

    Zhijun Li

    2016-01-01

    Full Text Available For vibration analysis of aeroengine blisk structure, a prestressed component modal synthesis (CMS super-element method is put forward with the fixed interface prestressing and free interface super-element approach. Based on this method, natural vibration characteristics of blisk structure are calculated at different modal truncation numbers. Comparing with the accurate result of global method, the selection principle of modal truncation number is obtained which affects the accuracy of prestressed CMS super-element method. Vibration response of two-stage blisk structure is calculated by this method, and the effects of different blade aspect ratios have been discussed on vibration characteristics. The results show that prestressed CMS super-element method is in the high accuracy and efficiency on blisk vibration analysis. Resonant frequencies in vibration response are nearly the same between the first-stage blisk and the second-stage blisk, and they are both approximately located in the range 588 Hz–599 Hz. The maximum displacement and dynamic stress are at blade tip and root of the first-stage blisk, respectively. Blade aspect ratio is a key factor of blisk vibration; the effects of blade aspect ratio on natural frequencies are different in the conditions of fixed width and fixed length. This research provides the theoretical basis for dynamic design of aeroengine compressor rotor system.

  11. Volcanic ash ingestion by a large gas turbine aeroengine: fan-particle interaction

    Science.gov (United States)

    Vogel, Andreas; Clarkson, Rory; Durant, Adam; Cassiani, Massimo; Stohl, Andreas

    2016-04-01

    Airborne particles from explosive volcanic eruptions are a major safety threat for aviation operations. The fine fraction of the emitted particles (atmosphere for days, or even weeks, and can affect commercial air traffic routes. Over the past century, there have been a considerable number of aircraft encounters with drifting volcanic ash clouds. Particles ingested into the engine cause erosion of upstream surfaces of compressor fan blades and rotor-path components, and can also cause contamination or blockage of electrical systems and the fuel system such as fuel nozzles and air bleed filters. Ash particles that enter the hot-section of the engine (combustor and turbine stages; temperature between 1400-1800°C) are rapidly heated above the glass transition temperature (about 650-1000°C) and become soft (or form a melt) and can stick as re-solidified deposits on nozzle guide vanes. The glass deposits change the internal aerodynamic airflow in the engine and can affect the cooling capability of the different components by clogging the cooling inlets/outlets, which can lead to a loss of power or flame-out. The nature of volcanic ash ingestion is primarily influenced by the fan at the front of the engine which produces the thrust that drives the aircraft. The ingested air is split between the core (compressor/combustor/turbine) and bypass (thrust) at a ratio of typically between, 1:5-10 on modern engines. Consequently, the ash particles are fractionated between the core and bypass by the geometry and dynamics of the fan blades. This study uses computational fluid dynamics (CFD) simulations of particle-laden airflows into a turbofan engine under different atmospheric and engine operation conditions. The main aim was to investigate the possible centrifugal effect of the fan blades as a function of particle size, and to relate this to the core intake concentration. We generated a generic 3D axial high-bypass turbofan engine using realistic dimensions of the turbofan

  12. Simultaneous Identification of Moving Vehicles and Bridge Damages Considering Road Rough Surface

    Directory of Open Access Journals (Sweden)

    Qingxia Zhang

    2013-01-01

    Full Text Available A method for the simultaneous identification of moving vehicles and the damages of the supporting structure from measured responses is presented. A two-axle vehicle model with two degrees of freedom (DOF is adopted. The extent of the damage and the vehicle parameters were chosen as the optimisation variables, which allow ill conditioning to be avoided and decrease the number of sensors required. The identification is performed by minimising the distance between the measured responses and the computed responses to given optimisation variables. The virtual distortion method (VDM was used, such that the response of the damaged structure can be computed from comparison with the intact structure subjected to the same vehicle excitation and to the response-coupled virtual distortions. These are related to the optimisation variables by the system impulse response matrix and are expressed by a linear system, which allowed both types of optimisation variables to be treated in a unified way. The numerical cost is reduced by using a moving influence matrix. The adjoint variable method is used for fast sensitivity analysis. A three-span bridge numerical example is presented, where the identification was verified with 5% root mean square (RMS measurement, and model, error whilst also considering the surface roughness of the road.

  13. Assessing Expected Fractional Damage of Above-ground Buildings from Air-to-surface Weapons based on Indirect Fire Concept

    OpenAIRE

    Jong Yil Park

    2010-01-01

    For the expected fractional damage of building targets from air-to-surface weapons, the US has used the JMEM/AS method, which is based on the direct-fire concept. However, the damage redistribution assumption in the direct-fire concept could induce serious errors in damage estimation of building targets. In this paper, a method for the expected fractional damage of building targets is proposed based on the indirect-fire concept. From the proposed model, it is shown that the joint munitions ef...

  14. Surface damage and structure evolution of recrystallized tungsten exposed to ELM-like transient loads

    Science.gov (United States)

    Yuan, Y.; Du, J.; Wirtz, M.; Luo, G.-N.; Lu, G.-H.; Liu, W.

    2016-03-01

    Surface damage and structure evolution of the full tungsten ITER divertor under transient heat loads is a key concern for component lifetime and plasma operations. Recrystallization caused by transients and steady-state heat loads can lead to degradation of the material properties and is therefore one of the most serious issues for tungsten armor. In order to investigate the thermal response of the recrystallized tungsten under edge localized mode-like transient thermal loads, fully recrystallized tungsten samples with different average grain sizes are exposed to cyclic thermal shocks in the electron beam facility JUDITH 1. The results indicate that not only does the microstructure change due to recrystallization, but that the surface residual stress induced by mechanical polishing strongly influences the surface cracking behavior. The stress-free surface prepared by electro-polishing is shown to be more resistant to cracking than the mechanically polished one. The resulting surface roughness depends largely on the loading conditions instead of the recrystallized-grain size. As the base temperature increases from room temperature to 400 °C, surface roughening mainly due to the shear bands in each grain becomes more pronounced, and sub-grains (up to 3 μm) are simultaneously formed in the sub-surface. The directions of the shear bands exhibit strong grain-orientation dependence, and they are generally aligned with the traces of {1 1 2} twin habit planes. The results suggest that twinning deformation and dynamic recrystallization represent the predominant mechanism for surface roughening and related microstructure evolution.

  15. Bragg-case limited projection topography study of surface damage in diamond-crystal plates

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Y; Krasnicki, S; Macrander, A T; Chu, Y S; Maj, J [Advanced Photon Source, Argonne National Laboratory, Argonne (United States)

    2005-05-21

    To characterize diamond monochromators for synchrotron radiation beamlines, images for a region 25 {mu}m below the surface were obtained. Topographical images of a Bragg-diffracted beam having a scattering angle (twice the Bragg angle) of 90 deg. were obtained from asymmetric reflections with a CCD area detector. A 25 {mu}m incident slit was used to section the sample topographically. Patchwork images for the full surface area, but limited in depth to the slit size, were assembled from microbeam images. The small extinction depths provided by the asymmetric reflection geometry, namely, 2.8 {mu}m and 3.5 {mu}m for ideal diamond crystals set for the (224) and (044) reflections, respectively, permitted data analyses for a region near the surface. The diamonds were synthetic type Ib (yellowish due to nitrogen impurities). They were in the shape of plates sized 6 x 5 mm and were 0.5 mm thick. Measurements were made using monochromatic bending magnet radiation at the Advanced Photon Source at 12.04 keV and 13.90 keV. Data obtained before and after chemical etching demonstrate that damage visible as contrast from saw grooves is largely removed by etching. Dislocation etch pits were observed after etching for the (111) surface but not for the (100) surface.

  16. Electron trapping and de-trapping in ion-beam-damaged diamond surfaces

    International Nuclear Information System (INIS)

    Full text: Ion beam damaged diamond surfaces subjected to electron irradiation are observed to develop a pronounced negative surface charge, the origin of which has remained a mystery. We show that this effect is associated with the capture of electrons into traps created by the ion irradiation process. The trapped charge increases with ion dose and incident electron current, and decreases with increasing sample temperature and laser illumination as the traps are depleted of charge. An activation energy for detrapping of about 1 5 eV is deduced from the temperature dependence of the charging. These results have important implications for the use of diamond in electron multipliers and cold cathode devices. Copyright (2005) Australian Institute of Physics

  17. 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.

  18. Transparency and damage tolerance of patternable omniphobic lubricated surfaces based on inverse colloidal monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, N; Belisle, RA; Hatton, B; Wong, TS; Aizenberg, J

    2013-07-31

    A transparent coating that repels a wide variety of liquids, prevents staining, is capable of self-repair and is robust towards mechanical damage can have a broad technological impact, from solar cell coatings to self-cleaning optical devices. Here we employ colloidal templating to design transparent, nanoporous surface structures. A lubricant can be firmly locked into the structures and, owing to its fluidic nature, forms a defect-free, self-healing interface that eliminates the pinning of a second liquid applied to its surface, leading to efficient liquid repellency, prevention of adsorption of liquid-borne contaminants, and reduction of ice adhesion strength. We further show how this method can be applied to locally pattern the repellent character of the substrate, thus opening opportunities to spatially confine any simple or complex fluids. The coating is highly defect-tolerant due to its interconnected, honeycomb wall structure, and repellency prevails after the application of strong shear forces and mechanical damage. The regularity of the coating allows us to understand and predict the stability or failure of repellency as a function of lubricant layer thickness and defect distribution based on a simple geometric model.

  19. 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.

  20. High-resolution 3-D imaging of surface damage sites in fused silica with Optical Coherence Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Guss, G; Bass, I; Hackel, R; Mailhiot, C; Demos, S G

    2007-10-30

    In this work, we present the first successful demonstration of a non-contact technique to precisely measure the 3D spatial characteristics of laser induced surface damage sites in fused silica for large aperture laser systems by employing Optical Coherence Tomography (OCT). What makes OCT particularly interesting in the characterization of optical materials for large aperture laser systems is that its axial resolution can be maintained with working distances greater than 5 cm, whether viewing through air or through the bulk of thick optics. Specifically, when mitigating surface damage sites against further growth by CO{sub 2} laser evaporation of the damage, it is important to know the depth of subsurface cracks below the damage site. These cracks are typically obscured by the damage rubble when imaged from above the surface. The results to date clearly demonstrate that OCT is a unique and valuable tool for characterizing damage sites before and after the mitigation process. We also demonstrated its utility as an in-situ diagnostic to guide and optimize our process when mitigating surface damage sites on large, high-value optics.

  1. Qualification of Indigenously Developed Special Coatings for Aero-Engine Components

    Directory of Open Access Journals (Sweden)

    V. Sambasiva Rao

    1999-10-01

    Full Text Available The demand for higher performance and reliability of aero-engiaes necessitates its components to worksatisfactorily under severe operating conditions. The durability of various components in these environmentis often enhanced by applying suitable coatings. The development of new materials/processing methods andalso various coatings to protect the components have been driven by the ever-increasing severity of theaero-engine internal environment. While the selection of a coating is dictated by the operating conditionsand the nature of the environment and also on the substrate, the durability of the coating depends uponthe mode of degradation of the coating and substrate in service.Though certification of an aero-engine after developmt obviously includes: validation of the componentsand its coatings, indigenous substitution of an already-qualified component system requires a re-orientationof the qualification methodology. This paper describes an approach for qualification of indigenously developedspecial coatings processes for application on aero-engine components. This approach has been adoptedsuccesshlly in validating several indigenous coatingslpmcesses, viz, aluminium-silicon diffusion coating appliedby pack cementation for oxidationhot comsion resistance, cobalt-chromium carbide coating by electrodepositionfor wear resistance, chromium carbide-nickel chromium coating applied by detonation gun and yttria-stabilisedzirconia thermal barrier coating applied by plasma spray.The approaih consists of a series of validation tests configured to assess the coating-substrate system.The rationale in evolving the qualification tests based on the type of coating, coating process, operating conditionsfor the components, probable failure modes and coating-base metal interaction, are described. In addition,comparison of the test results obtained on the test specimens coated with indigenously developed coatingsand imported coatings is also enumerated to show

  2. Methoxychlor and estradiol induce oxidative stress DNA damage in the mouse ovarian surface epithelium.

    Science.gov (United States)

    Symonds, Daniel A; Merchenthaler, Istvan; Flaws, Jodi A

    2008-09-01

    Estrogenic compounds such as 17beta-estradiol (E(2)) and methoxychlor (MXC) induce oxidative stress damage in breast cells and mouse ovarian follicles, respectively. However, little is known about whether estrogenic compounds cause oxidative stress in the ovarian surface epithelium (OSE). Thus, this work tested the hypothesis that E(2) and MXC cause oxidative stress in the OSE. To test this hypothesis, we employed an improved mouse tissue culture assay in which OSE cells were treated with hydrogen peroxide (H2O2; positive control), MXC, or E(2) +/- the anti-oxidant vitamin E, or progesterone. The cells then were subjected to a novel direct immunofluorescent assay in which cells in the microtiter plate were reacted with antibodies that detect oxidative damage to DNA (8-hydroxy-2'-deoxyguanosine). The signal was identified with a tyramide Alexa Fluor fluorescent probe and quantified by microfluorimetry. Correction for cellularity was carried out for each well with a fluorescent DNA dye system (CyQuant) at a different wavelength. After 24 h, the mean Alexa Fluor CyQuant ratio was 11.3 +/- 0.9 for controls, 132 +/- 15 for H2O2 treated positive control cells (p < or = 0.01 from control), 105 +/- 6.6 for E(2) treated cells (p < or = 0.01 from control), and 64 +/- 5.1 for MXC-treated cells (p < or = 0.01 from control). After 72 h, the mean ratio was 121 +/- 10.6 for controls, 391 +/- 23 for H2O2 treated cells (p < or = 0.01 from control), 200 +/- 15 for E(2) treated cells (p < or = 0.03), and 228 +/- 21 for MXC-treated cells (p < or = 0.01). Further, vitamin E, but not progesterone, protected OSE cells from E(2)- and MXC-induced oxidative damage. This study demonstrates the feasibility of direct immunofluorescent quantitation of DNA adducts in cell cultures without DNA extraction. Moreover, these data indicate that E(2) and MXC produce oxidative DNA damage in the OSE, and that this damage is prevented by the anti-oxidant vitamin E.

  3. The Electrochemical Machining Analysis of Aeroengine Blade Based on Isogeometric Method

    Directory of Open Access Journals (Sweden)

    Neng Wan

    2015-02-01

    Full Text Available Electrochemical machining is an important method for the blade in aeroengine. Analysis of electric field in machining gap is the basis of cathode design. For solving the low precision problem for sensitive boundary which is caused by traditional numerical analysis method, this paper proposed a method of promoting the analysis precision by using the isogeometric analysis. The NURBS basis functions are used to replace the Lagrange basis function for establishing the solving equations of the electrochemical machining gap. The problem of the noninterpolation feature belonging to the NURBS basis functions, which could bring the error for imposing Dirichlet boundary condition, is settled. At last, the superiority, including precision and the rate of convergence, of the isogeometric analysis is proved by the comparison test.

  4. Superplasticity in Aeroengine Titanium Alloy VT-9 and its Modified Compositions

    Directory of Open Access Journals (Sweden)

    Abhijit Dutta

    1986-04-01

    Full Text Available The alloy (Ti-6.5AL-3.3 Mo-1.6Zr-O.3Si is a Soviet composition designated VT-9. Excellent superplastic characteristics found by us in this alloy prompted us to explore the possibility of use of Si-free VT-9 in sheet form for superplastic forming. An optimum thermomechanical processing produced a microstructure that resulted in an elongation of 1700 per cent at a fairly high deformation rate (2 X 10-3 set-1. Thus, the same aeroengine alloy (VT-9 can be used for superplastically formed airframe parts in the Si-free condition. The present study also shows that for making the forming process commercially viable, deformation temperature could be lowered by temporarily alloying with hydrogen in a particular concentration range (0.1 to 0.2 wt per cent.

  5. Numerical Study of a Fuel Centrifugal Pump with Variable Impeller Width for Aero-engines

    Science.gov (United States)

    Wang, Bin; Guan, Huasheng; Ye, Zhifeng

    2015-12-01

    As typical pump with large flow rate and high reliability, centrifugal pumps in fuel system of aero-engines mostly regulate flow rate by flow bypass, which leads to low efficiency and large fuel temperature rise especially at low flow rate. An innovative fuel centrifugal pump with variable impeller width is a more effective way to regulate flow rate than flow bypass. To find external characteristics of the centrifugal pump with variable impeller width proposed in this paper, flow domain within the pump is simulated numerically and some primary performance parameters and their correlation are analyzed. Results show that flow rate of the pump can be regulated by variable impeller width and that efficiency for this scheme is higher than that for flow bypass. The higher outlet static pressure the pump runs at, the wider range of flow rates can be obtained with stronger nonlinear relationship between flow rate and impeller width.

  6. Unified Multi-speed analysis (UMA) for the condition monitoring of aero-engines

    Science.gov (United States)

    Nembhard, Adrian D.; Sinha, Jyoti K.

    2015-12-01

    For rotating machinery in which speeds and dynamics constantly change, performing vibration-based condition monitoring can be challenging. Thus, an effort is made here to develop a Unified Multi-speed fault diagnosis technique that can exploit useful vibration information available at various speeds from a rotating machine in a single analysis. Commonly applied indicators are computed from data collected from a rig at different speeds for a baseline case and different faults. Four separate analyses are performed: single speed at a single bearing, integrated features from multiple speeds at a single bearing, single speed for integrated features from multiple bearings and the proposed Unified Multi-speed analysis. The Unified Multi-speed approach produces the most conspicuous separation and isolation among the conditions tested. Observations made here suggest integration of more dynamic features available at different speeds improves the learning process of the tool which could prove useful for aero-engine condition monitoring.

  7. 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.

  8. Advanced Engineering Methods for Assessing Welding Distortion in Aero-Engine Assemblies

    Science.gov (United States)

    Jackson, Kathryn; Darlington, Roger

    2011-12-01

    Welding remains an attractive fabrication method for aero-engine assemblies, offering high production rates and reduced total cost, particularly for large complex assemblies. However, distortion generated during the welding process continues to provide a major challenge in terms of the control of geometric tolerances and residual stress. The welding distortion is influenced by the sequence and position of joints, the clamping configuration and the design of the assembly. For large complex assemblies the range of these options may be large. Hence the use of numerical simulation at an early stage of the product development process is valuable to enable a wide range of these factors to be explored with the aim of minimising welding distortions before production commences, and thereby reducing the product development time. In this paper, a new technique for simulation of welding distortions based on a shrinkage analysis is evaluated for an aero-engine assembly. The shrinkage simulations were built and solved using the ESI Group software Weld Planner. The rapid simulation speed enabled a wide range of welding plans to be explored, leading to recommendations for the fabrication process. The sensitivity of the model to mesh size and material properties is reported. The results of the shrinkage analysis were found to be similar to those of a transient analysis generated using ESI Group software SysWeld. The solution times were found to be significantly lower for the shrinkage analysis than the transient analysis. Hence it has been demonstrated that shrinkage analysis is a valuable tool for exploring the fabrication process of a welded assembly at an early stage of the product development process.

  9. Advanced Engineering Methods for Assessing Welding Distortion in Aero-Engine Assemblies

    International Nuclear Information System (INIS)

    Welding remains an attractive fabrication method for aero-engine assemblies, offering high production rates and reduced total cost, particularly for large complex assemblies. However, distortion generated during the welding process continues to provide a major challenge in terms of the control of geometric tolerances and residual stress. The welding distortion is influenced by the sequence and position of joints, the clamping configuration and the design of the assembly. For large complex assemblies the range of these options may be large. Hence the use of numerical simulation at an early stage of the product development process is valuable to enable a wide range of these factors to be explored with the aim of minimising welding distortions before production commences, and thereby reducing the product development time. In this paper, a new technique for simulation of welding distortions based on a shrinkage analysis is evaluated for an aero-engine assembly. The shrinkage simulations were built and solved using the ESI Group software Weld Planner. The rapid simulation speed enabled a wide range of welding plans to be explored, leading to recommendations for the fabrication process. The sensitivity of the model to mesh size and material properties is reported. The results of the shrinkage analysis were found to be similar to those of a transient analysis generated using ESI Group software SysWeld. The solution times were found to be significantly lower for the shrinkage analysis than the transient analysis. Hence it has been demonstrated that shrinkage analysis is a valuable tool for exploring the fabrication process of a welded assembly at an early stage of the product development process.

  10. A fiber laser welding of plastics assisted by transparent solid heat sink to prevent the surface thermal damages

    Science.gov (United States)

    Kurosaki, Yasuo; Satoh, Kimitoshi

    This paper deals with an innovative fiber laser welding method for engineering plastics assisted by a solid heat sink transparent to the laser beam for preventing any thermal damage on the surface. The features of this fiber laser welding procedure are (1) to place a solid heat sink transparent to the fiber laser beam in contact with an irradiated plastics to cool the surface during welding process, (2) to use no pigmentation or dye for radiation absorption enhancement, (3) to sustain thermal damage on the surface, and (4) to avoid the emission of harmful gas due to decomposition of plastics.

  11. Assessing Expected Fractional Damage of Above-ground Buildings from Air-to-surface Weapons based on Indirect Fire Concept

    Directory of Open Access Journals (Sweden)

    Jong Yil Park

    2010-08-01

    Full Text Available For the expected fractional damage of building targets from air-to-surface weapons, the US has used the JMEM/AS method, which is based on the direct-fire concept. However, the damage redistribution assumption in the direct-fire concept could induce serious errors in damage estimation of building targets. In this paper, a method for the expected fractional damage of building targets is proposed based on the indirect-fire concept. From the proposed model, it is shown that the joint munitions effectiveness manuals/air-to-surface (JMEM/AS method is not appropriate for building targets, especially for attacks with multiple aiming points. It is recommended that the indirect-fire concept should be adopted for weaponeering even for air-to-surface weapons. fire concept could induce serious errors in damage estimation of building targets. In this paper, a method for the expected fractional damage of building targets is proposed based on the indirect-fire concept. From the proposed model, it is shown that the JMEM/AS method is not appropriate for building targets, especially for attacks with multiple aiming points. It is recommended that the indirect-fire concept should be adopted for weaponeering even for air-to-surface weapons.Defence Science Journal, 2010, 60(5, pp.491-496, DOI:http://dx.doi.org/10.14429/dsj.60.571

  12. 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.

  13. Mussel Coating Protein-Derived Complex Coacervates Mitigate Frictional Surface Damage

    Science.gov (United States)

    2015-01-01

    The role of friction in the functional performance of biomaterial interfaces is widely reckoned to be critical and complicated but poorly understood. To better understand friction forces, we investigated the natural adaptation of the holdfast or byssus of mussels that live in high-energy surf habitats. As the outermost covering of the byssus, the cuticle deserves particular attention for its adaptations to frictional wear under shear. In this study, we coacervated one of three variants of a key cuticular component, mussel foot protein 1, mfp-1 [(1) Mytilus californianus mcfp-1, (2) rmfp-1, and (3) rmfp-1-Dopa], with hyaluronic acid (HA) and investigated the wear protection capabilities of these coacervates to surfaces (mica) during shear. Native mcfp-1/HA coacervates had an intermediate coefficient of friction (μ ∼0.3) but conferred excellent wear protection to mica with no damage from applied loads, F⊥, as high as 300 mN (pressure, P, > 2 MPa). Recombinant rmfp-1/HA coacervates exhibited a comparable coefficient of friction (μ ∼0.3); however, wear protection was significantly inferior (damage at F⊥ > 60 mN) compared with that of native protein coacervates. Wear protection of rmfp-1/HA coacervates increased 5-fold upon addition of the surface adhesive group 3,4-dihydroxyphenylalanine, (Dopa). We propose a Dopa-dependent wear protection mechanism to explain the differences in wear protection between coacervates. Our results reveal a significant untapped potential for coacervates in applications that require adhesion, lubrication, and wear protection. These applications include artificial joints, contact lenses, dental sealants, and hair and skin conditioners. PMID:26618194

  14. 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)

  15. An investigation into the aerospace industry with specific reference to the aero-engine sector and its electronic advancements

    OpenAIRE

    Gale, James William

    2006-01-01

    This investigation initially analyses the general trends seen within the core sectors of the aerospace industry. The external macro environment and the external industry environment are then assessed using the relevant models and processes that have been presented within the literature, with specific reference to the United Kingdom. In order to develop a focused and detailed understanding of an aero-engine manufacturer's internal environment, a case-study Rolls-Royce is incorporated. Recent t...

  16. Wavelet Correlation Feature Scale Entropy and Fuzzy Support Vector Machine Approach for Aeroengine Whole-Body Vibration Fault Diagnosis

    Directory of Open Access Journals (Sweden)

    Cheng-Wei Fei

    2013-01-01

    Full Text Available In order to correctly analyze aeroengine whole-body vibration signals, Wavelet Correlation Feature Scale Entropy (WCFSE and Fuzzy Support Vector Machine (FSVM (WCFSE-FSVM method was proposed by fusing the advantages of the WCFSE method and the FSVM method. The wavelet coefficients were known to be located in high Signal-to-Noise Ratio (S/N or SNR scales and were obtained by the Wavelet Transform Correlation Filter Method (WTCFM. This method was applied to address the whole-body vibration signals. The WCFSE method was derived from the integration of the information entropy theory and WTCFM, and was applied to extract the WCFSE values of the vibration signals. Among the WCFSE values, the WFSE1 and WCFSE2 values on the scale 1 and 2 from the high band of vibration signal were believed to acceptably reflect the vibration feature and were selected to construct the eigenvectors of vibration signals as fault samples to establish the WCFSE-FSVM model. This model was applied to aeroengine whole-body vibration fault diagnosis. Through the diagnoses of four vibration fault modes and the comparison of the analysis results by four methods (SVM, FSVM, WESE-SVM, WCFSE-FSVM, it is shown that the WCFSE-FSVM method is characterized by higher learning ability, higher generalization ability and higher anti-noise ability than other methods in aeroengine whole-vibration fault analysis. Meanwhile, this present study provides a useful insight for the vibration fault diagnosis of complex machinery besides an aeroengine.

  17. Application of image based measurement techniques for the investigation of aeroengine performance on a commercial aircraft in ground operation

    OpenAIRE

    Schröder, Andreas; Geisler, Reinhard; Schanz, Daniel; Agocs, Janos; Pallek, Dieter; Schroll, Michael; Klinner, Joachim; Beversdorff, Manfred; Voges, Melanie; Willert, Christian

    2014-01-01

    The investigation of the flow and sound field upstream and downstream of a full scale aeroengine is aimed at providing important reference data required for reliable modeling and prediction. In this regard a wide variety of contactless and non-invasive laser optical and acoustic measurement techniques have matured in recent years to allow their application on full scale aircraft. Within a measurement campaign involving an Airbus A320 DLR research aircraft inside a sound-attenuating hangar at ...

  18. Aqueous dispersions of oligomer-grafted carbon nanomaterials with controlled surface charge and minimal framework damage

    Science.gov (United States)

    Hu, Sheng; Chen, Shu; Menzel, Robert; Goode, Angela D.; Ryan, Mary P.; Porter, Alexandra E.; Shaffer, Milo S. P.

    2015-01-01

    Functionalised carbon nanomaterials (CNMs), with an undamaged carbon framework and controlled physiochemical properties, are desirable for a wide range of scientific studies and commercial applications. The use of a thermochemical grafting approach provides a versatile means to functionalise both multi-walled carbon nanotubes (MWCNTs) and carbon black (CB) nanoparticles without altering their inherent structure. The functionalisation process was investigated by employing various types of grafting monomers; to improve water solubility, reagents were chosen that introduced ionic character either intrinsically or after further chemical reaction. The degree of grafting for both MWCNTs and CB ranged from 3 to 27 wt%, as established by thermal gravimetric analysis (TGA). Raman spectroscopy confirmed that the structural framework of the MWNTs was unaffected by the thermochemical treatment. The effectiveness of the surface modification was demonstrated by significantly improved dispersibility and stability in water, and further quantified by zeta-potential analysis. The concentration of stable, individualised, grafted MWNTs in water ranged from 30 to 80 µg mL−1, whereas functionalised CB (CB) in water showed improved dispersibility up to ~460 µg mL−1 after centrifugation at 10, 000 g for 15 minutes. The successful preparation of structurally identical but differently functionalised nanoparticles panels, with high water compatibility and minimal framework damage, are useful for controlled experiments. For example, they can be used to explore the relationship between toxicological effects and specific physiochemical properties, such as surface charge and geometry. PMID:25254653

  19. A GM (1, 1 Markov Chain-Based Aeroengine Performance Degradation Forecast Approach Using Exhaust Gas Temperature

    Directory of Open Access Journals (Sweden)

    Ning-bo Zhao

    2014-01-01

    Full Text Available Performance degradation forecast technology for quantitatively assessing degradation states of aeroengine using exhaust gas temperature is an important technology in the aeroengine health management. In this paper, a GM (1, 1 Markov chain-based approach is introduced to forecast exhaust gas temperature by taking the advantages of GM (1, 1 model in time series and the advantages of Markov chain model in dealing with highly nonlinear and stochastic data caused by uncertain factors. In this approach, firstly, the GM (1, 1 model is used to forecast the trend by using limited data samples. Then, Markov chain model is integrated into GM (1, 1 model in order to enhance the forecast performance, which can solve the influence of random fluctuation data on forecasting accuracy and achieving an accurate estimate of the nonlinear forecast. As an example, the historical monitoring data of exhaust gas temperature from CFM56 aeroengine of China Southern is used to verify the forecast performance of the GM (1, 1 Markov chain model. The results show that the GM (1, 1 Markov chain model is able to forecast exhaust gas temperature accurately, which can effectively reflect the random fluctuation characteristics of exhaust gas temperature changes over time.

  20. An investigation of the chemical and physical properties of pristine, electrochromically damaged, and photochromically damaged KTiOPO{sub 4} (KTP) using surface analytical and optical spectroscopic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Quagliano, J.R.; Petrin, R.R.; Trujillo, T.C.; Cockroft, N.J.; Paffett, M.T.; Havrilla, G.; Maggiore, C.J. [Los Alamos National Lab., NM (United States); Jacco, J.C. [Philips Components, Saugerties, NY (United States)

    1994-10-01

    Single-crystal KTiOPO{sub 4} (KTP) is widely used as a nonlinear optical material in optics and lasers, but it can suffer irreversible damage from intense electric and electromagnetic fields; impurities, defects, vacancies, and electron/hole transfers are probably involved. This report shows results of surface and near-surface (bulk) studies using SIMS, Rutherford backscattering, PIXE, channeling, and XRF. The electrochromic damage may occur upon reduction of Ti{sup 4+} to Ti{sup 3+} by trapping electrons passing through the ion channels. Jahn-Teller distortions and Ti{sup 3+} absorption could produce the dark macroscopi damage. The claim that Ag ions could travel through the ion channels, is discounted by the RBS and SIMS data. RBS does suggest Ti ion migration, but this is not likely, according to the KTP structure and lack of Ti ion enhancement in the white residue. The 355 nm radiation could be absorbed into the UV band edge to inititate a photochemical process (gray tracking), which could be the charge transfer from the oxide ligand to Ti{sup 4+} to create Ti{sup 3+}.

  1. Flood Damage Analysis: First Floor Elevation Uncertainty Resulting from LiDAR-Derived Digital Surface Models

    Directory of Open Access Journals (Sweden)

    José María Bodoque

    2016-07-01

    Full Text Available The use of high resolution ground-based light detection and ranging (LiDAR datasets provides spatial density and vertical precision for obtaining highly accurate Digital Surface Models (DSMs. As a result, the reliability of flood damage analysis has improved significantly, owing to the increased accuracy of hydrodynamic models. In addition, considerable error reduction has been achieved in the estimation of first floor elevation, which is a critical parameter for determining structural and content damages in buildings. However, as with any discrete measurement technique, LiDAR data contain object space ambiguities, especially in urban areas where the presence of buildings and the floodplain gives rise to a highly complex landscape that is largely corrected by using ancillary information based on the addition of breaklines to a triangulated irregular network (TIN. The present study provides a methodological approach for assessing uncertainty regarding first floor elevation. This is based on: (i generation an urban TIN from LiDAR data with a density of 0.5 points·m−2, complemented with the river bathymetry obtained from a field survey with a density of 0.3 points·m−2. The TIN was subsequently improved by adding breaklines and was finally transformed to a raster with a spatial resolution of 2 m; (ii implementation of a two-dimensional (2D hydrodynamic model based on the 500-year flood return period. The high resolution DSM obtained in the previous step, facilitated addressing the modelling, since it represented suitable urban features influencing hydraulics (e.g., streets and buildings; and (iii determination of first floor elevation uncertainty within the 500-year flood zone by performing Monte Carlo simulations based on geostatistics and 1997 control elevation points in order to assess error. Deviations in first floor elevation (average: 0.56 m and standard deviation: 0.33 m show that this parameter has to be neatly characterized in order

  2. Surface contamination and electrical damage by focused ion beam: conditions applicable to the extraction of TEM lamellae from nanoelectronic devices

    International Nuclear Information System (INIS)

    Focused ion beams (FIBs) are widely applied during manufacturing and for failure analysis, as a preparation tool for cross sectional scanning electron microscopy or for the extraction of lamellae for (scanning) transmission electron microscopy investigation of nanoelectronic devices. The impact of the ion beam milling on surface contamination is investigated by time-of-flight secondary ion mass spectroscopy, while the electrical surface damage is analyzed by a micro four-point probe. It is shown that the redeposition of milled Ga and Cu reaches levels below sensitivity (5 × 1010 at cm−2) at less than 10 mm from FIB structures while the lateral range of electrical surface damage is an order of magnitude smaller. The major source of the redeposition is the resputtering of sputtered material from the sample that was previously deposited on the SEM column. The 2D distribution of the redeposition is asymmetric and is simulated well based on a simplified model of the column and sample configuration. The electrical surface damage mainly relates to the beam tails. Pt deposits for surface protection require much lower Ga+ ion doses, and therefore have less impact on the wafer surface contamination. However, the range of electrical surface damage is larger for Pt deposits due to increased beam scattering in the low vacuum during the Pt deposition. With these contamination and damage levels and ranges, ‘wafer return’, i.e. continuing the wafer processing after the FIB, can be considered feasible for back-end of line processes with the loss of only the analyzed die or, potentially, also its neighbor. For front-end of line processes the acceptable contamination levels are more stringent and the feasibility of wafer return will be more process specific. (paper)

  3. 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.

  4. MAINTENANCE LEVEL DECISION OF AERO-ENGINE BASED ON VPRS THEORY%基于VPRS理论的航空发动机送修等级决策

    Institute of Scientific and Technical Information of China (English)

    张海军; 左洪福; 梁剑

    2005-01-01

    An aero-engine is a typically repairable and complex system and its maintenance level has a close relationship with the maintenance cost. The inaccurate measurement for the maintenance level of an aero-engine can induce higher overhaul maintenance costs. Variable precision rough set (VPRS) theory is used to determine the maintenance level of an aero-engine. According to the relationship between condition information and performance parameters of aero-engine modules, decision rules are established for reflecting the real condition of an aeroengine when its maintenance level needs to be determined. Finally, the CF6 engine is used as an example to illustrate the method to be effective.%应用变精度粗糙集理论研究了发动机状态信息与单元体性能参数之间的关系,提出了一种基于信息熵属性约简的航空公司发动机维修等级决策方法,从而在维修决策时能够更加客观地反映发动机实际损伤程度.最后以CF6型发动机维修等级决策规则生成为例说明了该决策方法的有效性.

  5. Dynamic response of RC beams strengthened with near surface mounted Carbon-FRP rods subjected to damage

    Science.gov (United States)

    Capozucca, R.; Blasi, M. G.; Corina, V.

    2015-07-01

    Near surface mounted (NSM) technique with fiber reinforced polymer (FRP) is becoming a common method in the strengthening of concrete beams. The availability of NSM FRP technique depends on many factors linked to materials and geometry - dimensions of the rods used, type of FRP material employed, rods’ surface configuration, groove size - and to adhesion between concrete and FRP rods. In this paper detection of damage is investigated measuring the natural frequency values of beam in the case of free-free ends. Damage was due both to reduction of adhesion between concrete and carbon-FRP rectangular and circular rods and cracking of concrete under static bending tests on beams. Comparison between experimental and theoretical frequency values evaluating frequency changes due to damage permits to monitor actual behaviour of RC beams strengthened by NSM CFRP rods.

  6. Damage and deterioration monitoring of artwork by data fusion of 3D surface and hyperspectral measurements

    Science.gov (United States)

    Groves, Roger M.; Caballero, José; Quinzan, Ianisse; Ribes-Gómez, Emilio

    2014-05-01

    This paper describes the processing algorithm methodology and preliminary results from a novel optical-based system for the assessment of chemical and mechanical deterioration of artworks. The FP7 Syddarta Project prototype is composed of two optical channels: 1) a 3D imaging channel which acquires 3D surface data and multiband information in the visible spectral range; 2) an infrared hyperspectral imaging channel in the spectral range 900 to 2500 nm. The processing algorithms developed perform the system calibration, damage detection and chemical deterioration analysis. Both photometric and geometric calibrations have been implemented. The photometric calibration is based on a white reference and intensity map and compensates for variation in light intensities. The geometric calibration is based on planar homographies to determine the interior and exterior orientation of the projector and the two cameras. This is used to map the acquired data of the different sensors into a single reference frame. To acquire 3D data, a set of phase-shifted fringe patterns is projected on the object which are processed by Fourier transform. To identify mechanical deterioration, the acquired 3D cloud of points is meshed and differences in surface normals for a given radius are computed. To analyse the chemical deterioration of the pigments a supervised classification method has been implemented. First of all, spectral data is normalized with the Extended Multiplicative Scatter Correction algorithm. Then, data dimensionality is reduced by applying Principal Component Analysis and classification is done with Support Vector Machine. Results are presented showing the performance of the described algorithms.

  7. Nonlocal sparse model with adaptive structural clustering for feature extraction of aero-engine bearings

    Science.gov (United States)

    Zhang, Han; Chen, Xuefeng; Du, Zhaohui; Li, Xiang; Yan, Ruqiang

    2016-04-01

    Fault information of aero-engine bearings presents two particular phenomena, i.e., waveform distortion and impulsive feature frequency band dispersion, which leads to a challenging problem for current techniques of bearing fault diagnosis. Moreover, although many progresses of sparse representation theory have been made in feature extraction of fault information, the theory also confronts inevitable performance degradation due to the fact that relatively weak fault information has not sufficiently prominent and sparse representations. Therefore, a novel nonlocal sparse model (coined NLSM) and its algorithm framework has been proposed in this paper, which goes beyond simple sparsity by introducing more intrinsic structures of feature information. This work adequately exploits the underlying prior information that feature information exhibits nonlocal self-similarity through clustering similar signal fragments and stacking them together into groups. Within this framework, the prior information is transformed into a regularization term and a sparse optimization problem, which could be solved through block coordinate descent method (BCD), is formulated. Additionally, the adaptive structural clustering sparse dictionary learning technique, which utilizes k-Nearest-Neighbor (kNN) clustering and principal component analysis (PCA) learning, is adopted to further enable sufficient sparsity of feature information. Moreover, the selection rule of regularization parameter and computational complexity are described in detail. The performance of the proposed framework is evaluated through numerical experiment and its superiority with respect to the state-of-the-art method in the field is demonstrated through the vibration signals of experimental rig of aircraft engine bearings.

  8. Remaining useful life prognostics for aeroengine based on superstatistics and information fusion

    Institute of Scientific and Technical Information of China (English)

    Liu Junqiang; Zhang Malan; Zuo Hongfu; Xie Jiwei

    2014-01-01

    Remaining useful life (RUL) prognostics is a fundamental premise to perform condition-based maintenance (CBM) for a system subject to performance degradation. Over the past decades, research has been conducted in RUL prognostics for aeroengine. However, most of the prognostics technologies and methods simply base on single parameter, making it hard to demonstrate the spe-cific characteristics of its degradation. To solve such problems, this paper proposes a novel approach to predict RUL by means of superstatistics and information fusion. The performance degradation evolution of the engine is modeled by fusing multiple monitoring parameters, which manifest non-stationary characteristics while degrading. With the obtained degradation curve, prognostics model can be established by state-space method, and then RUL can be estimated when the time-varying parameters of the model are predicted and updated through Kalman filtering algo-rithm. By this method, the non-stationary degradation of each parameter is represented, and multi-ple monitoring parameters are incorporated, both contributing to the final prognostics. A case study shows that this approach enables satisfactory prediction evolution and achieves a markedly better prognosis of RUL.

  9. Remaining useful life prognostics for aeroengine based on superstatistics and information fusion

    Directory of Open Access Journals (Sweden)

    Liu Junqiang

    2014-10-01

    Full Text Available Remaining useful life (RUL prognostics is a fundamental premise to perform condition-based maintenance (CBM for a system subject to performance degradation. Over the past decades, research has been conducted in RUL prognostics for aeroengine. However, most of the prognostics technologies and methods simply base on single parameter, making it hard to demonstrate the specific characteristics of its degradation. To solve such problems, this paper proposes a novel approach to predict RUL by means of superstatistics and information fusion. The performance degradation evolution of the engine is modeled by fusing multiple monitoring parameters, which manifest non-stationary characteristics while degrading. With the obtained degradation curve, prognostics model can be established by state-space method, and then RUL can be estimated when the time-varying parameters of the model are predicted and updated through Kalman filtering algorithm. By this method, the non-stationary degradation of each parameter is represented, and multiple monitoring parameters are incorporated, both contributing to the final prognostics. A case study shows that this approach enables satisfactory prediction evolution and achieves a markedly better prognosis of RUL.

  10. 3 D FEM analysis of welding residual stress and deformation of aero-engine blisk

    Institute of Scientific and Technical Information of China (English)

    杨建国; 周号; 雷靖; 方洪渊; 张学秋; 曲伸

    2014-01-01

    Aero-engine blisk welded by electron beam welding(EBW)method is a complicated structure.Fixtures were used to control the deformation ofblisk during its manufacturing process.Finite element method was utilized to study the evolution of the welding residual stress and deformation of this structure.In which an attenuation function was applied to the double ellipsoid heat source model based on the characteristic ofEBW,and the effects offixtures on the welding residual stresses and deforamtion were also reserached.The simulation results showed that the temperature contour ofweld cross section vertical to the weld centerline followed a “V”shape.Moreover,large welding residual stress and distortion were found in the interface between blisk and fixtures.The stress concentration was reduced sufficiently in starting and end part ofweldment as the fixtures were removed after welding process,while the removing operation had almost no effects on the welding residual stress in the middle section ofweld bead.

  11. Direct Surge Margin Control for Aeroengines Based on Improved SVR Machine and LQR Method

    Directory of Open Access Journals (Sweden)

    Haibo Zhang

    2013-01-01

    Full Text Available A novel scheme of high stability engine control (HISTEC on the basis of an improved linear quadratic regulator (ILQR, called direct surge margin control, is derived for super-maneuver flights. Direct surge margin control, which is different from conventional control scheme, puts surge margin into the engine closed-loop system and takes surge margin as controlled variable directly. In this way, direct surge margin control can exploit potential performance of engine more effectively with a decrease of engine stability margin which usually happened in super-maneuver flights. For conquering the difficulty that aeroengine surge margin is undetectable, an approach based on improved support vector regression (SVR machine is proposed to construct a surge margin prediction model. The surge margin modeling contains two parts: a baseline model under no inlet distortion states and the calculation for surge margin loss under supermaneuvering flight conditions. The previous one is developed using neural network method, the inputs of which are selected by a weighted feature selection algorithm. Considering the hysteresis between pilot input and angle of attack output, an online scrolling window least square support vector regression (LSSVR method is employed to firstly estimate inlet distortion index and further compute surge margin loss via some empirical look-up tables.

  12. CFD predictions of LBO limits for aero-engine combustors using fuel iterative approximation

    Institute of Scientific and Technical Information of China (English)

    Hu Bin; Huang Yong; Wang Fang; Xie Fa

    2013-01-01

    Lean blow-out (LBO) is critical to operational performance of combustion systems in propulsion and power generation.Current predictive tools for LBO limits are based on decadesold empirical correlations that have limited applicability for modern combustor designs.According to the Lefebvre's model for LBO and classical perfect stirred reactor (PSR) concept,a load parameter (LP) is proposed for LBO analysis of aero-engine combustors in this paper.The parameters contained in load parameter are all estimated from the non-reacting flow field of a combustor that is obtained by numerical simulation.Additionally,based on the load parameter,a method of fuel iterative approximation (FIA) is proposed to predict the LBO limit of the combustor.Compared with experimental data for 19 combustors,it is found that load parameter can represent the actual combustion load of the combustor near LBO and have good relativity with LBO fuel/air ratio (FAR).The LBO FAR obtained by FIA shows good agreement with experimental data,the maximum prediction uncertainty of FIA is about ± 17.5%.Because only the non-reacting flow is simulated,the time cost of the LBO limit prediction using FIA is relatively low (about 6 h for one combustor with computer equipment of CPU 2.66 GHz × 4 and 4 GB memory),showing that FIA is reliable and efficient to be used for practical applications.

  13. Active generalized predictive control of turbine tip clearance for aero-engines

    Institute of Scientific and Technical Information of China (English)

    Peng Kai; Fan Ding; Yang Fan; Fu Qiang; Li Yong

    2013-01-01

    Active control of turbine blade tip clearance continues to be a concern in design and con-trol of gas turbines. Ever increasing demands for improved efficiency and higher operating temper-atures require more stringent tolerances on turbine tip clearance. In this paper, a turbine tip clearance control apparatus and a model of turbine tip clearance are proposed;an implicit active generalized predictive control (GPC), with auto-regressive (AR) error modification and fuzzy adjustment on control horizon, is presented, as well as a quantitative analysis method of robust per-turbation radius of the system. The active clearance control (ACC) of aero-engine turbine tip clear-ance is evaluated in a lapse-rate take-off transient, along with the comparative and quantitative analysis of the stability and robustness of the active tip clearance control system. The results show that the resultant active tip clearance control system with the improved GPC has favorable steady-state and dynamic performance and benefits of increased efficiency, reduced specific fuel consump-tion, and additional service life.

  14. A 5-DOF Model for Aeroengine Spindle Dual-rotor System Analysis

    Institute of Scientific and Technical Information of China (English)

    HU Qinghua; DENG Sier; TENG Hongfei

    2011-01-01

    This paper develops a five degrees of freedom (5-DOF) model for aeroengine spindle dual-rotor system dynamic analysis.In this system, the dual rotors are supported on two angular contact ball bearings and two deep groove ball bearings, one of the latter-mentioned bearings works as the inter-shaft bearing.Driven by respective motors, the dual rotors have different co-rotating speeds.The proposed model mathematically formulates the nonlinear displacements, elastic deflections and contact forces of beatings with consideration of 5-DOF and coupling of dual rotors.The nonlinear equations of motions of dual rotors with 5-DOF are solved using Runge-Kutta-Fehlberg algorithm.In order to investigate the effect of the introduced 5-DOF and nonlinear dynamic bearing model, we compare the proposed model with two models: the 3-DOF model of this system only considering three translational degrees of freedom (Gupta, 1993, rotational freedom is neglected); the 5-DOF model where the deep groove ball bearings are simplified as linear elastic spring (Guskov, 2007).The simulation results verify Gupta's prediction (1993) and show that the rotational freedom of rotors and nonlinear dynamic model of bearings have great effect on the system dynamic simulation.The quantitative results are given as well.

  15. Investigation of surface characteristics evolution and laser damage performance of fused silica during ion-beam sputtering

    Science.gov (United States)

    Xu, Mingjin; Dai, Yifan; Zhou, Lin; Shi, Feng; Wan, Wen; Xie, Xuhui; Sui, Tingting

    2016-08-01

    Surface characteristics have great influence on the optical properties especially the laser radiation resistivity of optics. In this paper, the surface characteristics evolutions of fused silica during ion-beam sputtering and their effects on the laser damage performance were investigated. The results show that roughness change is strongly removal depth dependent and a super-smooth surface (0.25 nm RMS) can be obtained by the ion-induced smoothing effect. The concentration of metal impurities (especially Ce element) in subsurface can be effectively decreased after the removal of polishing re-deposition layer. During ion-beam sputtering process, the plastic scratches can be removed while the brittle cracks can be broadened and passivated without increase in the depth direction. Laser damage threshold of fused silica improved by 36% after ion-beam sputtering treatment. Research results have a guiding significance for ion-beam sputtering process technology of fused silica optics.

  16. Real-time analysis of the surface reaction and the growing process of damages in multiple environment materials and assessment of their surface properties

    International Nuclear Information System (INIS)

    National Research Institute for Metals takes part in the basic parts of this project to conduct a kinetic study on the surface reaction and the growing process of radiation damages in metals and semiconductors caused by ion radiation. In the first stage of this research, an instrument for real-time measurement of the changes in phonon features was developed. Using this, the generation of structural disturbance and the thermal relaxation time were measured for the first. In the second stage, we attempted to develop high-speed analyzing techniques for the surface reaction and the growing process of damages during ion radiation using the instrument developed in the first stage. Phonon correlation length (La) for near GaAs surface was estimated on a basis of the raman spectra obtained by the real-time measurement. Thus, La was found to decrease in inverse proportion to the cube root of radiation amount. (M.N.)

  17. Surface Damage Growth Mitigation on KDP/DKDP Optics Using Single-Crystal Diamond Micro-Machining

    International Nuclear Information System (INIS)

    A process whereby laser-initiated surface damage on KDP/DKDP optics is removed by spot micro-machining using a high-speed drill and a single-crystal diamond bit, is shown to mitigate damage growth for subsequent laser shots. Our tests show that machined dimples on both surfaces of an AR coated doubler (KDP) crystal are stable, for 526nm, ∼ 3.2ns pulses at ∼ 12J/cm2 fluences. Other tests also confirmed that the machined dimples on both surfaces of an AR coated tripler (DKDP) crystal are stable, for 351nm, ∼ 3ns pulses at ∼ 8J/cm2. We have demonstrated successful mitigation of laser-initiated surface damage sites as large as 0.14mm diameter on DKDP, for up to 1000 shots at 351nm, 13J/cm2, ∼ 11ns pulse length, and up to 10 shots at 351nm, 8J/cm2, 3ns. Details of the method are presented, including estimates for the heat generated during micro-machining and a plan to implement this method to treat pre-initiated or retrieved-from-service, large-scale optics for use in high-peak-power laser applications

  18. 航空发动机封严技术的进展%Improvement of Aero-Engine Sealing Technology

    Institute of Scientific and Technical Information of China (English)

    沈虹; 郑天慧; 陈玉洁

    2011-01-01

    封严技术一直是高性能航空发动机研发工作的重要组成部分,先进封严技术是满足发动机耗油率、推重比、污染物排放、耐久性及寿命期成本目标的关键技术。通过减少发动机内部气流的泄漏量,可大大提高发动机的性能和效率。本文针对航空发动机典型封严技术,详细介绍了石墨封严、篦齿封严、刷式封严的结构特点及其技术改进和发展趋势。重点阐述了德国MTU公司开发的新型刷式封严技术,其独特的结构解决了刷式封严掉毛这一技术难题。%Sealing technology has always been a significant part of high-performance aero-engine development. And advanced sealing technology is the key to achieve lower SFC, higher thrust-to-weight ratio, less emission, improved endurance and less life cycle cost. The performance and efficiency of aero-engines can be greatly improved by reducing the leakage of inner flow. Focusing on the typical seal technology used in aero-engines, this paper introduces the features, technology improvement and development tendencies of graphite sealing, labyrinth sealing and brush sealing in details, particularly the new brush sealing technolo-gy developed by MTU, which solved bristle looses by its unique configuration.

  19. RHEED study of irradiation-induced surface damage processes in Si and alpha-Al sub 2 O sub 3

    CERN Document Server

    Muto, S; Tanabé, T

    2002-01-01

    Surface damaging processes of crystalline silicon and alumina (alpha-Al sub 2 O sub 3) by gas ion (H sup + , He sup + , Ar sup + , 0.5-5 keV) irradiation at a moderate temperature range (300-450 K) were examined by reflection high-energy electron diffraction (RHEED). In order to explain the changes in RHEED intensities, a phenomenological kinetic equation was extended to take a dynamical interaction between hydrogen and target atoms into account. Apparent activation energies for simultaneous recovery and the cross-sections for damage production were derived and compared for different implant species by fitting the kinetic equation to the experimental data. The obtained physical parameters showed that the surface damage by inert gas irradiation could be understood simply by the dpa (displacement per atom) rates due to nuclear stopping. In case of H sup + irradiation, on the other hand, electronic stopping and chemical interaction between hydrogen and the matrix atoms significantly affected the damaging rate an...

  20. Energetic laser cleaning of metallic particles and surface damage on silica optics: investigation of the underlying mechanisms

    Science.gov (United States)

    Shen, Nan; Demos, Stavros G.; Negres, Raluca A.; Rubenchik, Alexander M.; Harris, Candace D.; Matthews, Manyalibo J.

    2015-11-01

    Surface particulate contamination on optics can lead to laser-induced damage hence limit the performance of high power laser system. In this work we focus on understanding the fundamental mechanisms that lead to damage initiation by metal contaminants. Using time resolved microscopy and plasma spectroscopy, we studied the dynamic process of ejecting ~30 μm stainless steel particles from the exit surface of fused silica substrate irradiated with 1064 nm, 10 ns and 355 nm, 8 ns laser pulses. Time-resolved plasma emission spectroscopy was used to characterize the energy coupling and temperature rise associated with single, 10-ns pulsed laser ablation of metallic particles bound to transparent substrates. Plasma associated with Fe(I) emission lines originating from steel microspheres was observe to cool from laser energy.

  1. 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

  2. Novel Framework for Reduced Order Modeling of Aero-engine Components

    Science.gov (United States)

    Safi, Ali

    The present study focuses on the popular dynamic reduction methods used in design of complex assemblies (millions of Degrees of Freedom) where numerous iterations are involved to achieve the final design. Aerospace manufacturers such as Rolls Royce and Pratt & Whitney are actively seeking techniques that reduce computational time while maintaining accuracy of the models. This involves modal analysis of components with complex geometries to determine the dynamic behavior due to non-linearity and complicated loading conditions. In such a case the sub-structuring and dynamic reduction techniques prove to be an efficient tool to reduce design cycle time. The components whose designs are finalized can be dynamically reduced to mass and stiffness matrices at the boundary nodes in the assembly. These matrices conserve the dynamics of the component in the assembly, and thus avoid repeated calculations during the analysis runs for design modification of other components. This thesis presents a novel framework in terms of modeling and meshing of any complex structure, in this case an aero-engine casing. In this study the affect of meshing techniques on the run time are highlighted. The modal analysis is carried out using an extremely fine mesh to ensure all minor details in the structure are captured correctly in the Finite Element (FE) model. This is used as the reference model, to compare against the results of the reduced model. The study also shows the conditions/criteria under which dynamic reduction can be implemented effectively, proving the accuracy of Criag-Bampton (C.B.) method and limitations of Static Condensation. The study highlights the longer runtime needed to produce the reduced matrices of components compared to the overall runtime of the complete unreduced model. Although once the components are reduced, the assembly run is significantly. Hence the decision to use Component Mode Synthesis (CMS) is to be taken judiciously considering the number of

  3. Volcanic ash ingestion by a large gas turbine aeroengine: fan-particle interaction

    Science.gov (United States)

    Vogel, Andreas; Clarkson, Rory; Durant, Adam; Cassiani, Massimo; Stohl, Andreas

    2016-04-01

    for aeroengine operation is a fraction of the ambient (observed or forecast) ash quantity.

  4. In situ spectroscopic ellipsometry study of the oxide etching and surface damaging processes on silicon under hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, I.M.; Manso, J.Y.; Guzman, J.R.; Weiner, B.R.; Morell, G.

    2000-07-01

    The authors employed in situ ellipsometry in the monitoring of surface damage to monocrystalline silicon (Si) substrates under hydrogen plasma conditions. These measurements were complemented with spectroscopic ellipsometry and Raman spectroscopy, in order to characterize the surface conditions. It was found that heating the Si substrate to 700 C in the presence of molecular hydrogen produces etching of the native oxide layer, which is typically 10 {angstrom} thick. When the already hot and bare silicon surface is submitted to hydrogen plasma, it deteriorates very fast, becoming rough and full of voids. Modeling of the spectroscopic ellipsometry data was used to obtain a quantitative physical picture of the surface damage, in terms of roughness layer thickness and void fraction. The results indicate that by the time a thin film starts to grow on these silicon surfaces, like in the chemical vapor deposition of diamond, the roughness produced by the hydrogen plasma has already determined to a large extent the rough nature of the film to be grown.

  5. System and method for laser-based, non-evaporative repair of damage sites in the surfaces of fused silica optics

    Energy Technology Data Exchange (ETDEWEB)

    Adams, John J.; Bolourchi, Masoud; Bude, Jeffrey D.; Guss, Gabriel M.; Jarboe, Jeffery A.; Matthews, Manyalibo J.; Nostrand, Michael C; Wegner, Paul J.

    2016-09-06

    A method for repairing a damage site on a surface of an optical material is disclosed. The method may involve focusing an Infrared (IR) laser beam having a predetermined wavelength, with a predetermined beam power, to a predetermined full width ("F/W") 1/e.sup.2 diameter spot on the damage site. The focused IR laser beam is maintained on the damage site for a predetermined exposure period corresponding to a predetermined acceptable level of downstream intensification. The focused IR laser beam heats the damage site to a predetermined peak temperature, which melts and reflows material at the damage site of the optical material to create a mitigated site.

  6. APPLICATION OF ROUGH SET THEORY TO MAINTENANCE LEVEL DECISION-MAKING FOR AERO-ENGINE MODULES BASED ON INCREMENTAL KNOWLEDGE LEARNING

    Institute of Scientific and Technical Information of China (English)

    陆晓华; 左洪福; 蔡景

    2013-01-01

    The maintenance of an aero-engine usually includes three levels ,and the maintenance cost and period greatly differ depending on the different maintenance levels .To plan a reasonable maintenance budget program , airlines would like to predict the maintenance level of aero-engine before repairing in terms of performance parame-ters ,which can provide more economic benefits .The maintenance level decision rules are mined using the histori-cal maintenance data of a civil aero-engine based on the rough set theory ,and a variety of possible models of upda-ting rules produced by newly increased maintenance cases added to the historical maintenance case database are in-vestigated by the means of incremental machine learning .The continuously updated rules can provide reasonable guidance suggestions for engineers and decision support for planning a maintenance budget program before repai-ring .The results of an example show that the decision rules become more typical and robust ,and they are more accurate to predict the maintenance level of an aero-engine module as the maintenance data increase ,which illus-trates the feasibility of the represented method .

  7. Raman and FTIR Studies of Silicon Carbide Surface Damage from Palladium Implantation in Presence of Hydrogen

    Science.gov (United States)

    Muntele, I.; Ila, D.; Muntele, C. J.; Poker, D. B.; Hensley, D. K.; Larkin, David (Technical Monitor)

    2001-01-01

    The ion implantation in a crystal such as silicon carbide will cause both damage in the ion track and in the substrate at the end of the ion track. We used both keV, and MeV Pd ions in fabricating electronic chemical sensors in silicon carbide, which can operate at elevated temperatures. In order to study the feasibility of fabricating an optical chemical sensor (litmus sensor), we need to understand the optical behavior of the embedded damage in the presence of hydrogen, as well as the potential chemical interaction of silicon carbide broken lattice bonds with the hydrogen dissociated from gas by palladium. Implanted samples of silicon carbide were studied using both Raman spectroscopy and FTIR (Fourier Transform-Infrared). The results of this work will be presented during the meeting.

  8. A DUAL-SURFACE DAMAGE MODEL AND EVALUATION FOR NATURAL SOILS WITHIN THE THERMOMECHANICAL FRAMEWORK

    Institute of Scientific and Technical Information of China (English)

    Xuan Guo; Chenggang Zhao; Dajun Yuan; Mengshu Wang

    2008-01-01

    Naturally deposited or residual soils exhibit more complicated behavior than re-molded clays. A dual-surfarae damage model for structured soils is developed based on the ther-modynamies framework established in our first paper. The shift stresses and the transformation between the generalized dissipative stress space and actual stress space are established following a systematic procedure. The corresponding constitutive behavior of the proposed model is deter-mined, which reflects the internal structural configuration and damage behavior for geomaterials. Four evolution variables kij (i = D, R; j = V, S) and the basic parameters λ, s,v and e0 are introduced to account for the progressive loss of internal structure for natural clays. A series of fully triaxial tests and isotropic compression tests are performed for structured and reconstituted samples of Beijing and Zhengzhou natural clays. The validation of the proposed model is examined by comparing the numerical results with the experimental data.

  9. Surface and internal microstructure damage of He-ion-irradiated CLAM steel studied by cross-sectional transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, P.P. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhan, Q., E-mail: qzhan@mater.ustb.edu.cn [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Fu, Z.Y.; Wei, Y.P. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Y.M. [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Wang, F.M. [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Ohnuki, S. [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Wan, F.R. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2015-11-15

    Good understanding of blistering and embrittlement mechanism depends on good investigation of surface and internal microstructure damage of gas-ion-irradiated materials. Internal and surface microstructure of He{sup +} ion irradiated CLAM steel were examined by cross-sectional transmission electron microscopy combining focused ion beam. Variation of helium bubble density and size distribution versus depth in CLAM steel after high dose helium irradiation at room temperature was investigated. The average size of helium bubble increased within 100–400 nm but decreased near the non-irradiated matrix with the increase of depth, while the density followed a reverse trend. The formation and growth mechanism of helium bubble is different at different irradiation depth. The formation of a zone of large bubbles under the surface is the main reason of surface blistering and flaking. Helium induced irradiation swelling and surface blistering at low temperature were also discussed. - Highlights: • Microstructure of helium irradiated CLAM steel was investigated by FIB and TEM. • The nucleation of helium bubble was controlled by both different mechanisms. • The substructure of surface blisters has been analyzed in detail by XTEM. • Helium induced surface blistering and irradiation swelling have been discussed.

  10. Surface and internal microstructure damage of He-ion-irradiated CLAM steel studied by cross-sectional transmission electron microscopy

    International Nuclear Information System (INIS)

    Good understanding of blistering and embrittlement mechanism depends on good investigation of surface and internal microstructure damage of gas-ion-irradiated materials. Internal and surface microstructure of He+ ion irradiated CLAM steel were examined by cross-sectional transmission electron microscopy combining focused ion beam. Variation of helium bubble density and size distribution versus depth in CLAM steel after high dose helium irradiation at room temperature was investigated. The average size of helium bubble increased within 100–400 nm but decreased near the non-irradiated matrix with the increase of depth, while the density followed a reverse trend. The formation and growth mechanism of helium bubble is different at different irradiation depth. The formation of a zone of large bubbles under the surface is the main reason of surface blistering and flaking. Helium induced irradiation swelling and surface blistering at low temperature were also discussed. - Highlights: • Microstructure of helium irradiated CLAM steel was investigated by FIB and TEM. • The nucleation of helium bubble was controlled by both different mechanisms. • The substructure of surface blisters has been analyzed in detail by XTEM. • Helium induced surface blistering and irradiation swelling have been discussed

  11. Characterization of surface damage of a solid plate under tensile loading using nonlinear Rayleigh waves

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    This letter reports experimental observation of a direct correlation between the acoustic nonlinearity parameter (NP) measured with nonlinear Rayleigh waves and the accumulation of plasticity damage in an AZ31 magnesium alloy plate specimen.Rayleigh waves are generated and detected with wedge transducers,and the NPs are measured at different stress levels.The results show that there is a significant increase in the NPs with monotonic tensile loads surpassing the material's yielding stress.The research sugge...

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

    Directory of Open Access Journals (Sweden)

    A. I. Belyaeva

    2014-07-01

    Full Text Available 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 W6 + ions of 20 MeV energy. Ar+ 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.

  13. 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

  14. Finite element simulation for damage detection of surface rust in steel rebars using elastic waves

    Science.gov (United States)

    Tang, Qixiang; Yu, Tzuyang

    2016-04-01

    Steel rebar corrosion reduces the integrity and service life of reinforced concrete (RC) structures and causes their gradual and sudden failures. Early stage detection of steel rebar corrosion can improve the efficiency of routine maintenance and prevent sudden failures from happening. In this paper, detecting the presence of surface rust in steel rebars is investigated by the finite element method (FEM) using surface-generated elastic waves. Simulated wave propagation mimics the sensing scheme of a fiber optic acoustic generator mounted on the surface of steel rebars. Formation of surface rust in steel rebars is modeled by changing material's property at local elements. In this paper, various locations of a fiber optic acoustic transducer and a receiver were considered. Megahertz elastic waves were used and different sizes of surface rust were applied. Transient responses of surface displacement and pressure were studied. It is found that surface rust is most detectable when the rust location is between the transducer and the receiver. Displacement response of intact steel rebar is needed in order to obtain background-subtracted response with a better signal-to-noise ratio. When the size of surface rust increases, reduced amplitude in displacement was obtained by the receiver.

  15. Effect and suppression of parasitic surface damage in neutron irradiated CMOS Monolithic Active Pixel Sensors

    CERN Document Server

    Deveaux, M; Scharrer, P; Stroth, J

    2016-01-01

    CMOS Monolithic Active Pixel Sensors (MAPS) were chosen as sensor technology for the vertex detectors of STAR, CBM and the upgraded ALICE-ITS. They also constitute a valuable option for tracking devices at future e+e- colliders. Those applications require a substantial tolerance to both, ionizing and non-ionizing radiation. To allow for a focused optimization of the radiation tolerance, prototypes are tested by irradiating the devices either with purely ionizing radiation (e.g. soft X-rays) or the most pure sources of non-ionizing radiation available (e.g. reactor neutrons). In the second case, it is typically assumed that the impact of the parasitic $\\gamma$-rays found in the neutron beams is negligible. We checked this assumption by irradiating MAPS with $\\gamma$-rays and comparing the radiation damage generated with the one in neutron irradiated sensors. We conclude that the parasitic radiation doses may cause non-negligible radiation damage. Based on the results we propose a procedure to recognize and to ...

  16. 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.

  17. Wear surface damage of a Stainless Steel EN 3358 aeronautical component subjected to sliding

    Directory of Open Access Journals (Sweden)

    Ferdinando Felli

    2013-01-01

    Full Text Available The present paper describes the failure analysis of an aircraft component subjected to several episodes of in service failure, resulted in loss of the aircraft safety. Modern aircrafts are provided with mechanical systems which have the task to open not pressurized hatches during landing. The components of such systems are subject to considerable mechanical stresses in harsh environment (presence of moisture and pollutants, significant and sudden temperature variations. The system is constituted by a sliding piston, a related nipple and by a locking system consisting of 4 steel spheres which are forced into a countersink machined on the piston when the hatches is open. The whole system is activated by a preloaded spring. The machined parts, nipple and piston, are made of EN3358 steel (X3CrNiMo13-8-2, a precipitation hardening stainless steel with very low content of carbon often used in the aerospace. The samples provided by the manufacturer present different types of damage all referable to phenomena relative to the sliding of the piston inside the nipple. The present paper describes the different damage observed and the microstructure of the material, then are reported the results obtained from the characterization of the material of the samples by means of optical and electronic microscopy, carried out to define the mechanisms involved in the system seizure. In order to define the primary cause of failure and to propose solutions to be adopted, also analyzing the criticality of using this PH stainless steel for this application, the results of different tests were compared with system design and working data.

  18. 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.

  19. Prevention of Ultraviolet (UV)-Induced Surface Damage and Cytotoxicity of Polyethersulfone Using Atomic Layer Deposition (ALD) Titanium Dioxide

    Science.gov (United States)

    Petrochenko, Peter E.; Scarel, Giovanna; Hyde, G. Kevin; Parsons, Gregory N.; Skoog, Shelby A.; Zhang, Qin; Goering, Peter L.; Narayan, Roger J.

    2013-04-01

    Nanostructured surfaces are finding use in several medical applications, including tissue scaffolds and wound dressings. These surfaces are frequently manufactured from biocompatible polymers that are susceptible to ultraviolet (UV) damage. Polyethersulfone (PES) is a biocompatible polymer that undergoes oxidation and degradation when exposed to ultraviolet (UV) light. A uniform TiO2 coating can protect PES during exposure to UV sources (e.g., germicidal lamps and sunlight). The goal of this study was to determine whether atomic layer deposition (ALD) can successfully be used to grow TiO2 onto PES, protect it from UV irradiation, and reduce macrophage in vitro cytotoxicity. TiO2 was ALD-coated onto PES at 21 nm thickness. Uncoated PES exposed to UV for 30 min visibly changed color, whereas TiO2-coated PES showed no color change, indicating limited degradation. Macrophages exposed to UV-treated PES for 48 h showed reduced cell viability (via MTT assay) to 18% of control. In contrast, the cell viability for UV-treated TiO2-coated PES was 90% of control. Non-UV treated PES showed no decrease in cell viability. The results indicate that ALD of TiO2 thin films is a useful technique to protect polymers from UV damage and to retain low cytotoxicity to macrophages and other types of cells that are involved in wound healing. TiO2- coated PES membranes also have potential use in direct methanol fuel cells and in wastewater treatment membranes.

  20. Therapeutic Effects of Sodium Hyaluronate on Ocular Surface Damage Induced by Benzalkonium Chloride Preserved Anti-glaucoma Medications

    Institute of Scientific and Technical Information of China (English)

    Xing Liu; Fen-Fen Yu; Yi-Min Zhong; Xin-Xing Guo; Zhen Mao

    2015-01-01

    Background:Long-term use of benzalkonium chloride (BAC)-preserved drugs is often associated with ocular surface toxicity.Ocular surface symptoms had a substantial impact on the glaucoma patients' quality of life and compliance.This study aimed to investigate the effects of sodium hyaluronate (SH) on ocular surface toxicity induced by BAC-preserved anti-glaucoma medications treatment.Methods:Fifty-eight patients (101 eyes),who received topical BAC-preserved anti-glaucoma medications treatment and met the severe dry eye criteria,were included in the analysis.All patients were maintained the original topical anti-glaucoma treatment.In the SH-treated group (56 eyes),unpreserved 0.3% SH eye drops were administered with 3 times daily for 90 days.In the control group (55 eyes),phosphate-buffered saline were administered with 3 times daily for 90 days.Ocular Surface Disease Index (OSDI) questionnaire,break-up time (BUT) test,corneal fluorescein staining,corneal and conjunctival rose Bengal staining,Schirmer test,and conjunctiva impression cytology were performed sequentially on days 0 and 91.Results:Compared with the control group,SH-treated group showed decrease in OSDI scores (Kruskal-Wallis test:H =38.668,P < 0.001),fluorescein and rose Bengal scores (Wilcoxon signed-ranks test:z =-3.843,P< 0.001,and z =-3.508,P < 0.001,respectively),increase in tear film BUT (t-test:t =-10.994,P < 0.001) and aqueous tear production (t-test:t =-10.328,P < 0.001) on day 91.The goblet cell density was increased (t-test:t =-9.981,P < 0.001),and the morphology of the conjunctival epithelium were also improved after SH treatment.Conclusions:SH significantly improved both symptoms and signs of ocular surface damage in patients with BAC-preserved anti-glaucoma medications treatment.SH could be proposed as a new attempt to reduce ocular surface toxicity,and alleviate symptoms of ocular surface damage in BAC-preserved anti-glaucoma medications treatment.

  1. Chatter stability prediction in four-axis milling of aero-engine casings with bull-nose end mill

    Directory of Open Access Journals (Sweden)

    Zhou Xu

    2015-12-01

    Full Text Available An analytical model for chatter stability prediction in bull-nose end milling of aero-engine casings is presented in this paper. And the mechanics and dynamics variations due to the complex cutter and workpiece geometry are considered by analyzing the effects of the lead angle on the milling process. Firstly, the tool-workpiece engagement region is obtained by using a previously developed method and divided into several disk elements along the tool-axis direction. Secondly, a 3D dynamic model for stability limit calculation is developed and simplified into a 1D model in normal direction considering only the dominant mode of the workpiece. Then the cutting force coefficients, the start and exit angles corresponding to each disk element are determined. And the total stability lobe diagram is calculated using an iterative algorithm. Finally, several experimental tests are carried out to validate the feasibility and effectiveness of the proposed prediction approach.

  2. Nutritional disorders in spruce (Picea abies) as a consequence of damage to needle surfaces and deposition of atmospheric nitrogenous compounds - one of the mechanisms of forest decline

    Energy Technology Data Exchange (ETDEWEB)

    Glatzel, G.; Kazda, M.; Katzensteiner, K.; Grill, D.; Halbwachs, G.

    1987-01-01

    A hypothesis to explain the damages as combined effect of needle damage by polluted fog and high deposition of plant useable nitrogen is discussed. It has been shown, that epicuticular was structures can be destroyed by exposure to polluted wet deposition, especially under conditions where cycles of wetting and drying of leave surface alternate without wash off by rain. When water containing plant available nitrogen is deposited on damaged leave surfaces, exchange with the interior of the leaves may disturb the ratios of individual nutrients in the leaves and cause metabolic stress. High ammonium concentrations in the precipitation water and low pH-values increase the leaching of plant nutrients, especially magnesium, potassium, manganese and zinc. By use of fertilizers or soil amendments the nutritional status of the trees can be improved. As long as polluted precipitation reaches the canopy and causes damage to the needle surfaces additional detrimental effects, such as easy invasion of pathogenic fungi, remain.

  3. Micro- and nano-scale damage on the surface of W divertor component during exposure to high heat flux loads with He

    Science.gov (United States)

    Li, C.; Greuner, H.; Zhao, S. X.; Böswirth, B.; Luo, G. N.; Zhou, X.; Jia, Y. Z.; Liu, X.; Liu, W.

    2015-11-01

    Micro- and nano-scale surface damage on a W divertor component sample exposed to high heat flux loads generated with He atoms has been investigated through SEM, EBSD, AFM and FIB-SEM. The component sample was supplied by the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) and AT&M company, China, and the loading experiment was performed in the GLADIS facility at IPP Garching, Germany. Two typical damage structures were observed on the surface: the first one is characterized by obvious blisters and some grooves formed from ruptured blisters, and the other one is a kind of porous structure accompanying with at least ∼25 nm surface material loss. As the grain orientation is further away from , the damage morphology gradually changes from the former structure to the latter. The possible damage mechanism is discussed.

  4. Fatigue Damage Evaluation of Cr-Mo Steel with In-Situ Ultrasonic Surface Wave Assessment

    International Nuclear Information System (INIS)

    Although the ultrasonic method has been developed and used widely in the fields, it has been used only for measuring the defect size and thickness loss. In this study, the relationship between surface wave attenuation through micro-crack growth and variation of velocity under repeated cyclic loading has been investigated. The specimens are adopted from 2.25Cr-1Mo steel, which is used for power plant and pipeline system, and have dimensions of 200x40x4mm. The results of ultrasonic test with a 5MHz transducer show that surface wave velocity gradually decreases from the point of 60% of fatigue life and the crack length of 2mm with the increasing fatigue cycles. From the results of this study, it is found that the technique using the ultrasonic velocity change is one of very useful methods to evaluate the fatigue life nondestructively

  5. Analysis of surface damage produced by pulsed laser ablation on metal Al and semiconductor Si

    Institute of Scientific and Technical Information of China (English)

    ManBao-Yuan; LiuAi-Hua; 等

    1998-01-01

    The suraface morphological changesd produced by Nd:YAG pulsed laser ablation of metal Al and semiconductor Si were carefully examined and analyzed by using scanning elkectron microscope.The formation mechanism of the droplets was discussed.and the reasons for formation of the microcracks on the laser irradiated area of the target surface were analyzed by calculating the thermal stress,the vapor pressure and the shock pressure induced by the laser supported detonation.

  6. Surface modification of basalt with silane coupling agent on asphalt mixture moisture damage

    Energy Technology Data Exchange (ETDEWEB)

    Min, Yahong; Fang, Ying; Huang, Xiaojun; Zhu, Yinhui; Li, Wensheng [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Yuan, Jianmin [College of Materials Engineering, Hunan University, Changsha, 410082 (China); Tan, Ligang [College of Mechanical and Vehicle Engineering, Hunan University, Changsha, 410082 (China); Wang, Shuangyin [State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Wu, Zhenjun, E-mail: wooawt@163.com [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China)

    2015-08-15

    Graphical abstract: - Highlights: • A new silane coupling agent was synthesized based on KH570. • Basalt surface was modified using the new silane coupling agent. • Chemical bond between basalt and the new silane coupling agent was formed. • Asphalt mixture which used modified basalt show superior water stability. - Abstract: A new silane coupling agent was synthesized based on γ-(methacryloyloxy) propyltrimethoxysilane (KH570). The surface of basalt rocks was modified by KH570 and the new silane coupling agent (NSCA), and the interfacial interaction between silane coupling agent and basalt was also studied. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis showed that the silane coupling agent molecule bound strongly with basalt rocks. Scanning electronic microscopy (SEM) observation showed that a thin layer of coupling agent was formed on the surface of modified basalt. The boiling test and immersion Marshall test confirmed that the moisture sensitivity of basalt modified with the new silane coupling agent increased more significantly than that untreated and treated with KH570. The Retained Marshall Strength of basalt modified with the new coupling agent increased from 71.74% to 87.79% compared with untreated basalt. The results indicated that the new silane coupling agent played an important role in improving the interfacial performance between basalt and asphalt.

  7. Ameliorated Chrysotile-induced DNA Damage in Human Embryo Lung Cells by Surface Modification of Chrysotile With Rare Earth Compounds

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective In view of the fact that asbestos is not only a key occupational hazard, but also an important environmental pollutant, it is necessary to develop a proper method to decrease the carcinogenecity of asbestos fibers. This study was designed to determine if the surface modification of chrysotile asbestos fiber (CAF) with rare earth compounds (REC) can ameliorate CAF-induced DNA damages in human embryo lung (HEL) cells. Methods After incubation with REC solution at different concentrations at room temperature for 1 h, natural and REC-pretreated CAF was added to cell culture at various doses. At the selected time as the experiment designed, DNA damages of the HEL cells were detected by Unscheduled DNA Synthesis (UDS) and Single Cell Gel Electrophoresis (SCGE) assays. Results The UDS induced by natural CAF was elevated with the increase of CAF doses. There was a good dose-response relationship between the UDS and the amount of CAF in the medium and the coefficient of correlation (R) was 0.958 at P<0.05. In REC-pretreated CAF groups, the UDS declined with the increase of REC doses. Both catalase (CAT) and dimethylsulfoxide (DMSO) also reduced the CAF-induced enhancement of UDS. In SCGE assay, CAF induced DNA chain breakage and the magnitude of DNA chain breakage increased in a dose-dependent manner and the coefficient of correlation (R) was 0.992 at p<0.01, while REC-pretreated CAF significantly decreased the induction of DNA chain breakage in a dose-dependent manner(r=0.989, p<0.05). Conclusion It can be concluded that CAF-induced DNA damages in HEL cells may be partly mediated by oxygen derivatives, and the surface modification of CAF with REC might hide critical sites on the fiber surface, thereby reducing the fiber-mediated production of oxygen derivation and lowering the CAF-induced UDS and DNA chain breakage in HEL cells.

  8. Ameliorated Chrysotille—induced DNA Damage in Human Embryo Lung Cells by Surface Modification of Chrysotile With Rare Earth Compounds

    Institute of Scientific and Technical Information of China (English)

    FANJING-GUANG; WANGQI-EN; 等

    2001-01-01

    Objective:In view of the fact that asbestos is not only a key occupational hazard,but also an important enviromental pollutant,it is necessary to develop a proper method to decrease the carcinogenectiy of asbestos fibers.This study was designed to determine if the surface modification of chrysotile asbestos fiber(CAF)with rare earth compounds(REC) can ameliorate CAF-induced DNA damages in human embryo lung(HEL)cells,Methods:After incubation with REC solution at different concentrations at room temperature for 1h,natural and REC-pretreated CAF was added to cell culture at various doses.At the selected time as the experiment designed ,DNA damages of the HEL cells were detected by Unscheduled DNA Synthesis(UDS) and Single Cell Gel Electrophoresis(SCGE) assays.Results:The UDS induced by natural CAF was elevated with the increase of CAF doses,There was a good dose-response relationship between the UDS and the amount of CAF in the mdeium and the coefficient of correlation(R) was 0.958 at P<0.05,In REC-pretreated CAF groups,the use declined with the increase of REC doses.Both catalase(CAT) and dimethylsulfoxide(DMSO)also reduced the CAF-induced enhancement of UDS.In SCGE assay,CAF induced DNA chain breakage and the magnitude of DNA chain breakage increased in a dosedependent manner and the coefficient of correlation(R))was 0.992 at P<0.01,while REC-pretreated CAF significantly decreased the induction of DNA chain breakage in a dose-dependent manner(r=0.989,P<0.05).Conclusion:It can be concluded that CAF-induced DNA damages in HEL cells may be partly mediated by oxygen derivatives,and the surface modification of CAF with REC might hide critical sites on the fiber surface ,thereby reducing the fiber-mediated production of oxygen derivation and lowering the CAF-induced UDS and DNA chani breakage in HEL cells.

  9. Surface modification of basalt with silane coupling agent on asphalt mixture moisture damage

    Science.gov (United States)

    Min, Yahong; Fang, Ying; Huang, Xiaojun; Zhu, Yinhui; Li, Wensheng; Yuan, Jianmin; Tan, Ligang; Wang, Shuangyin; Wu, Zhenjun

    2015-08-01

    A new silane coupling agent was synthesized based on γ-(methacryloyloxy) propyltrimethoxysilane (KH570). The surface of basalt rocks was modified by KH570 and the new silane coupling agent (NSCA), and the interfacial interaction between silane coupling agent and basalt was also studied. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis showed that the silane coupling agent molecule bound strongly with basalt rocks. Scanning electronic microscopy (SEM) observation showed that a thin layer of coupling agent was formed on the surface of modified basalt. The boiling test and immersion Marshall test confirmed that the moisture sensitivity of basalt modified with the new silane coupling agent increased more significantly than that untreated and treated with KH570. The Retained Marshall Strength of basalt modified with the new coupling agent increased from 71.74% to 87.79% compared with untreated basalt. The results indicated that the new silane coupling agent played an important role in improving the interfacial performance between basalt and asphalt.

  10. 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.

  11. Ar ion damage on the surface of soda-lime-silica glass

    International Nuclear Information System (INIS)

    Ar ion sputtering is one of the most accepted techniques for depth profiling in practical X-ray photoelectron spectroscopy (XPS) analysis, while this technique is known to be inadequate for quantitative analysis of glass including mobile ions such as soda-lime-silica glass. In this paper, the profile change in soda-lime-silica glass (70.4SiO2, 0.9Al2O3, 7.3MgO, 7.8CaO, 13.6Na2O in mol%) was investigated on the dependence of the accelerating voltage at 2 and 4 kV for Ar ion sputtering. On the other hand, buckminsterfullerene (C60) ion sputtering has been recently recognized to succeed the precise XPS depth analysis of soda-lime-silica glass without compositional change. Then, the surface states after Ar ion sputtering at 2 and 4 kV were precisely examined with the depth analysis using the C60 ion sputtering. It was firstly confirmed using C60 ion sputtering that the higher accelerating voltage caused the deeper implantation of the Ar ion and the larger migration of mobile ions.

  12. 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)

    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)

  13. Surface Characterizations of Fretting Fatigue Damage in Aluminum Alloy 7075-T6 Clamped Joints: The Beneficial Role of Ni–P Coatings

    Directory of Open Access Journals (Sweden)

    Reza H. Oskouei

    2016-02-01

    Full Text Available This paper aims to characterize the surface damage as a consequence of fretting fatigue in aluminum alloy 7075-T6 plates in double-lap bolted joints through XRD, surface profilometry, and SEM analyses. The main focus was on the surface roughness and chemical phase composition of the damaged zone along with the identification of fretting fatigue crack initiations over the surface of the material. The surface roughness of the fretted zone was found to increase when the joint was clamped with a higher tightening torque and tested under the same cyclic loading. Additionally, MgZn2 (η/ή precipitates and ZnO phase were found to form onto the surface of uncoated aluminum plate in the fretted and worn zones. The formation of the ZnO phase was understood to be a result of frictional heat induced between the surface of contacting uncoated Al 7075-T6 plates during cyclic loading and exposure to the air. The beneficial role of electroless nickel-phosphorous (Ni–P coatings in minimizing the fretting damage and thus improving the fretting fatigue life of the aluminum plates was also studied. The results showed that the surface roughness decreased by approximately 40% after applying Ni–P coatings to the Al 7075-T6 plates.

  14. 发动机推力销载荷测量中的温度修正方法研究%Temperature Modification Method in Direct Thrust Measurement of Aero-engine

    Institute of Scientific and Technical Information of China (English)

    牛宏伟; 张强

    2015-01-01

    以某航空发动机推力销载荷测量项目为背景,介绍了基于RTD的推力销表面温度测量方法。通过温度试验获得温度对应变桥输出的影响曲线,然后结合发动机车台试验对推力销温度进行了实时测量。根据推力销环境温度试验和载荷标定试验,得到推力销测量载荷的温度修正,表明温度对测量结果的影响。%Under the background of Aero-engine Direct Thrust Measurement program, the temperature measure-ment method of thrust pin surface based on RTD ( Resistance Temperature Detector ) is introduced. The impact of temperature ranging on strain gage bridge output voltage is obtained by temperature experiment. The real tempera-ture of the thrust pin under the condition of engine bench test is scaled. Combining the result of temperature experi-ment, engine bench test and the previous load calibration, the modification of temperature to the installation thrust force is acquired to indicate the influence of temperature to measurement precision.

  15. Fatigue Crack Growth in Complex Residual Stress Fields Due to Surface Treatment and Foreign Object Damage under Simulated Flight Cycles

    OpenAIRE

    Zabeen, S.

    2011-01-01

    Foreign object damage (FOD) refers to the damage that generally takes place in aero engine fans and compressor blades, due to the ingestion of hard particles/debris during aeroplane take-off, taxiing, or landing. Such damage can reduce the fatigue life expectancy of the turbine engine components by 50%. Residual stresses and small microcracks induced by the high speed FOD impacts are two root causes that result in premature failure of these components. One way to mitigate the FOD related f...

  16. Civil Aeroengine Maintenance Effect Evaluation Based on Data Envelopment Analysis%基于数据包络分析的民航发动机维修效果评价

    Institute of Scientific and Technical Information of China (English)

    付旭云; 王瑞; 钟诗胜; 朱级明

    2011-01-01

    对民航发动机维修效果进行评价可以为发动机承修厂的选择提供决策支持,同时有助于发现发动机承修厂的潜在问题。为了实现发动机维修效果的评价,首先提出了评价指标选择的原则,在此基础上给出了发动机维修效果评价指标体系,建立了基于数据包络分析的C2WH模型的发动机维修效果评价模型,并对模型的构建过程进行了描述。针对决策单元输入输出选择存在的问题,提出了基于指标值变换的解决方法。最后,通过应用案例验证了所提方法的有效性。%Evaluating civil aeroengine maintenance effect can provide decision-making support for selection of aeroengine maintenance,repair and overhaul(MRO)company,and also help to find existing potential problems in aeroengine MRO company.To evaluate civil aeroengine maintenance effect,four principles on selecting evaluation indicators are proposed.Based on them,the aeroengine maintenance effect evaluation system is given,and then aeroengine maintenance effect evaluation model based on C2WH of Data Envelopment Analysis(DEA) is established.The modeling process of the model is also described.To solve the existing problem in selecting inputs and outputs of the decision-making unit,a solution based on indicator value transformation is proposed.Finally,a case study shows that the proposed method is effective.

  17. A prediction scheme of the static fracture strength of MEMS structures based on the characterization of damage distribution on a processed surface

    International Nuclear Information System (INIS)

    This paper presents a scheme for predicting the strength of MEMS structures patterned into arbitrary shapes by deep reactive ion etching of a silicon wafer. The scheme is based on the inhomogeneous defect distribution on the etched surfaces. Single-crystal silicon specimens with different shapes were subjected to four-point bending tests with monotonically increasing load. The distributions of the fracture strength were described using two-parameter Weibull statistics, where the two parameters are defined as functions of the etching depth representing the inhomogeneity of the damage on the etched surface in the direction perpendicular to the wafer. In order to estimate the distribution of the local strength determined by the local level of damage, the etched surfaces of specimens without a notch were tested in three different bending directions corresponding to three different stress distributions, and three different strength levels were given due to surface roughness conditions caused by the non-uniformity of the etching process. The estimated values of the parameters were used to estimate the fracture strength of four types of notched specimens with different notch tip radii. The results of comparison between the distributions of predicted strengths and experimental data showed that the fracture strength of arbitrarily shaped structures is predictable on the basis of the information obtained from specimens without notch, by taking into account the characteristics of etched surface, i.e. the inhomogeneous damage. (paper)

  18. The effect of pulse duration on the growth rate of laser-induced damage sites at 351 nm on fused silica surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Negres, R A; Norton, M A; Liao, Z M; Cross, D A; Bude, J D; Carr, C W

    2009-10-29

    Past work in the area of laser-induced damage growth has shown growth rates to be primarily dependent on the laser fluence and wavelength. More recent studies suggest that growth rate, similar to the damage initiation process, is affected by a number of additional parameters including pulse duration, pulse shape, site size, and internal structure. In this study, we focus on the effect of pulse duration on the growth rate of laser damage sites located on the exit surface of fused silica optics. Our results demonstrate, for the first time, a significant dependence of growth rate at 351 nm on pulse duration from 1 ns to 15 ns as {tau}{sup 0.3} for sites in the 50-100 {micro}m size range.

  19. Low Order ZP/LTR Control for Aeroengines%航空发动机的低阶ZP/LTR控制

    Institute of Scientific and Technical Information of China (English)

    冯正平; 孙健国

    2001-01-01

    Multivariable robust control for aeroengines is studied. The approach for constructing low order design plant model is presented. Since the low order design plant model is constructed by wrapping the aeroengines' actuators with a special feedback, it has lower order than that of design plant model constructed by augmenting approach. Based on the low order design plant model, the original ZP/LTR approach turns to low order ZP/LTR approach, and the order of the low order ZP/LTR controller is much lower than that of ZP/LTR controller, thus it can be more easily implemented. Simulational results of control for a turbofan engine show the effectiveness of the low order ZP/LTR approach.%研究了航空发动机的多变量鲁棒控制,提出了低阶设计对象模型的构造方法。该模型是通过对被控对象的发动机执行机构进行特定输出反馈而得到的,它与被控对象模型阶次相同,明显低于目前常用的增广设计方法设计对象模型的阶次。基于低阶设计对象模型,作者以前研究的ZP/LTR设计方法转化为低阶ZP/LTR设计方法,应用该方法使设计控制器的阶次明显降低,从而更易实现。通过对某型涡扇发动机的仿真研究验证了低阶ZP/LTR设计方法的有效性。

  20. Influence of Na2SiO3 addition on surface microstructure and cavitation damage characteristics for plasma electrolytic oxidation of Al-Mg alloy

    Science.gov (United States)

    Lee, Jung-Hyung; Son, Chang-Ryeon; Kim, Seong-Jong

    2016-01-01

    Recently, plasma electrolytic oxidation (PEO) has emerged as a promising surface modification technique to improve surface properties of Al alloys. In this study, PEO coating process for Al-Mg alloy was conducted with two different electrolyte solutions under the same electrical parameters: one was potassium hydroxide (KOH) aqueous solution, and the other involved potassium hydroxide aqueous solution with sodium silicate (Na2SiO3). The surface morphology was observed with scanning electron microscope (SEM) and elemental compositions were identified with energy dispersive spectroscopy (EDS) analysis. The chemical structures of PEO coatings were identified by X-ray diffraction analysis. Cavitation experiment was performed using ultrasonic vibratory cavitation erosion testing apparatus. Cavitation damage of PEO coatings was characterized using SEM and three-dimensional (3D) microscope. The result indicated that the surface of Al-Mg alloy were successfully modified having complete different surface morphologies by changing electrolyte composition. It was found that the surface morphology had a great influence on the cavitation damage behavior of PEO coating.

  1. 航空发动机密封技术应用研究%Application Research of Seal Technologies for Aeroengine

    Institute of Scientific and Technical Information of China (English)

    胡广阳

    2012-01-01

    介绍了石墨圆周密封、刷式密封、指状密封、气膜密封和其他几种新型密封技术研究的新进展和在航空发动机上的应用,对密封技术的机理、特点和在研究中遇到的问题进行了分析和讨论。阐明了为适应航空发动机的发展要求,密封技术应进行材料、工艺、结构、机理等多方面的开创性设计,并提出在密封技术设计中应引入控制概念的观点。%The development and application of aeroengine seal technology were introduced, which include high misalignment carbon seals, brush seal, finger seal, film sealand other new kinds of seal technology. The principles, characteristics, problems were analyzed and discussed. The innovative design on materials, process, structures and principles of seal technology should be conducted to meet aeroengine development requirements and the views of control concept were introduced in seal technology design.

  2. In situ Barely Visible Impact Damage detection and localization for composite structures using surface mounted and embedded PZT transducers: A comparative study

    Science.gov (United States)

    Dziendzikowski, M.; Kurnyta, A.; Dragan, K.; Klysz, S.; Leski, A.

    2016-10-01

    Application of guided waves excited by a network of PZT transducers integrated with a given structure is one of the promising approaches to Structural Health Monitoring (SHM). The performance of a SHM system based on PZT network is rooted in two distinct areas of the technology development, that is the hardware and the signal analysis. The first includes the type of transducers used to built a network and the way of their integration with a monitored structure. For composites, besides the possibility of the transducers attachment to a surface of an element, also embedding of PZTs into their internal structure is available. In the article Barely Visible Impact Damage (BVID) detection capabilities as well as selected physical properties of the embedded and surface mounted PZT transducers are compared in broad frequency range of the excitation. Among the compared parameters are the impedance and capacitance spectra up to 600 kHz. The damage detection capabilities are compared in the range 100-350 kHz. In addition to purely qualitative detection of damages a new algorithm of their localization is proposed and compared between the embedded and surface attached transducers for the frequency optimal to detect BVIDs.

  3. Comparative study of ion implantation caused anomalous surface damage in silicon studied by spectroscopic ellipsometry and Rutherford backscattering spectrometry

    NARCIS (Netherlands)

    Lohner, T.; Fried, M.; Khanh, N.Q.; Petrik, P.; Wormeester, H.; El-Sherbiny, M.A.

    1999-01-01

    Damage created by ion implantation of 150 keV Ne+ and 800 keV Ar+ ions in single-crystalline silicon was characterized using Spectroscopic Ellipsometry (SE) and Rutherford Backscattering Spectrometry (RBS) in combination with channeling. Results from both methods unambiguously show the presence of a

  4. Impact of Surface Temperature on Fatigue Damage in Asphalt Pavement%路表温度对沥青路面疲劳损伤的影响

    Institute of Scientific and Technical Information of China (English)

    韦璐; Sascha KAYSER; Frohmut WELLNER

    2013-01-01

    To evaluate anti-fatigue performance of asphalt pavement impacted by temperature effectively and solve the problem of inaccurately prediction of fatigue damage by adopting a single fixed temperature, the impact of different surface temperatures and their combinations on fatigue damage in asphalt pavement is analyzed based on Miner law of accumulated fatigue damage, taking the temperature field prediction model of asphalt pavement provided by Dresden University of Technology in Germany for example. According to plenty of measured surface temperature data, different surface temperature combinations and their representative values in temperature intervals are determined and the change regularity of fatigue damage in asphalt pavement is studied. The analysis result shows that (1) the fatigue damage predicted by adopting surface temperature combinations is more accurate than that predicted by adopting a single fixed temperature; (2) when the number of temperature intervals forming temperature combination is much more, the predicted fatigue damage in asphalt pavement is more accurate, while when the number of temperature intervals was much less, the fatigue damage impacted by representative values in temperature intervals varies obviously; (3) the fatigue damage impacted by high temperature ( or upper limit) for representative value of temperature intervals is larger than the one by low temperature (lower limit).%为准确评价温度影响下沥青路面结构的抗疲劳性能,解决采用某单一固定温度预估疲劳损伤不够精确的问题,以德国德累斯顿工业大学提出的路面温度场预估模型为例,基于Miner疲劳累积损伤定理,分析路表不同温度及其组合对沥青路面疲劳损伤的影响.通过大量实测的路表温度数据,确定不同的路表温度组合及其组合内温度区间的温度代表值,研究路面结构疲劳损伤变化的规律.分析结果表明:采用由多个温度区间组成的路表温度组合预

  5. Third-body Wear Damage Produced in CoCr Surfaces by Hydroxyapatite and Alumina Ceramic Debris: A 10-cycle Metal-on-Metal Simulator Study

    Directory of Open Access Journals (Sweden)

    Thomas Halim

    2015-12-01

    Full Text Available Ceramic particles are believed to be particularly abrasive due to their extreme hardness. Ceramic debris has been reported in retrieved total hip arthroplasty (THA due to chipping and fracture of alumina components or by flaking of hydroxyapatite from implant coatings. However there appears to be no abrasion ranking of such particle behavior. The hypotheses in this study were, i alumina particles would create large scratches in CoCr surfaces and ii hydroxyapatite would produce very mild scratching comparable to bone-cement particles. Hydroxyapatite beads came in two types of commercial powders while the flakes were scraped from retrieved femoral stems. Alumina beads came in two commercial powders and flakes were retrieved from a fractured ceramic head. Particle morphologies were determined by SEM and CoCr surface damage by interferometry and SEM. Six 38-mm MOM were mounted inverted in a hip simulator and run with ceramic particles inserted for a 10-second test. Surface-roughness ranking after 10-second abrasion test revealed that bone cement and hydroxyapatite produced least damage to CoCr surfaces while alumina produced the most. Alumina increased surface roughness 19-fold greater than either hydroxyapatite or bone-cement particles. The alumina debris produced numerous scratches typically 20-80 µm wide with some up to 140µm wide. Surprisingly the alumina beads and flakes were pulverized within the 10-second test interval and remained adherent to the CoCr surfaces. Additionally, the hydroxyapatite although also a ceramic had no more effect on CoCr than the bone-cement debris. Use of well-characterized and commercially available alumina and hydroxyapatite powders appeared advantageous for abrasion tests. These new data indicated that such ceramic powders have merit.

  6. Metallurgical investigation of defects in super alloy 718 mill forms intended for aeroengine applications; Metallurgische Schadensanalyse an Halbzeugen aus der Superlegierung 718 fuer Triebwerksapplikationen

    Energy Technology Data Exchange (ETDEWEB)

    Gopala Krishna, V.; Srinivas, M. [Defence Metallurgical Research Lab., Hyderabad (India); Janakiram, G.D. [Utah State Univ., Logan, UT (United States); Murty, C.H.V.S.; Venugopal Reddy. A. [Regional Center for Military Airworthiness (Materials), Hyderabad (India)

    2008-10-15

    Super alloy 718 finds extensive utilization, particularly in aero engine industry, due to its excellent strength, low cycle fatigue and creep resistance. The alloy was manufactured using vacuum induction melting followed by vacuum arc remelting techniques. The electrodes, after thermo-mechanical processing to hot rolled square bar and flat forms, were ultrasonically inspected prior to machining of aeroengine compressor blades. During machining, crack-like defects were noticed. Visual / Stereo microscopic examination revealed that the defect was along the length of airfoil and was located at mid airfoil width. The defects were filled with dark gray colored debris. Fractographic examination of the crack facets revealed flaky gray region containing number of cracks and bright region with dimpled rupture features covered with debris. Analysis of the debris indicated the presence of oxygen in addition to the elements present in the material, suggesting that the debris is essentially an oxide. These features were correlated with processing histories and defect morphologies. (orig.)

  7. Spray dispersion in a generic premix module for aeroengine combustors; Spray-Dispersion in einem generischen Vormischmodul fuer Flugtriebwerks-Brennkammern

    Energy Technology Data Exchange (ETDEWEB)

    Becker, J.

    2004-08-01

    The liquid fuel placement and fuel spray dispersion in an annular, swirling flow is investigated experimentally. The liquid fuel is injected into the annular airflow in the radial direction by means of plain jet nozzles in the center body. Optical measurement techniques are applied at near-realistic aeroengine operating conditions, particularly at elevated values of air pressure. An investigation of the liquid plain jet in crossflow concerning penetration, break-up and atomization using visualization techniques and phase-Doppler anemometry is followed by the actual investigation of spray dispersion. This includes detailed measurements of the airflow by laser-Doppler anemometry, yielding turbulence data such as velocity fluctuations and length scales. The Stokes number is employed to analyze and interpret the data and transfer the results to a full power operating condition that cannot be investigated experimentally. (orig.)

  8. Enhanced Etching, Surface Damage Recovery, and Submicron Patterning of Hybrid Perovskites using a Chemically Gas-Assisted Focused-Ion Beam for Subwavelength Grating Photonic Applications.

    Science.gov (United States)

    Alias, Mohd S; Yang, Yang; Ng, Tien K; Dursun, Ibrahim; Shi, Dong; Saidaminov, Makhsud I; Priante, Davide; Bakr, Osman M; Ooi, Boon S

    2016-01-01

    The high optical gain and absorption of organic-inorganic hybrid perovskites have attracted attention for photonic device applications. However, owing to the sensitivity of organic moieties to solvents and temperature, device processing is challenging, particularly for patterning. Here, we report the direct patterning of perovskites using chemically gas-assisted focused-ion beam (GAFIB) etching with XeF2 and I2 precursors. We demonstrate etching enhancement in addition to controllability and marginal surface damage compared to focused-ion beam (FIB) etching without precursors. Utilizing the GAFIB etching, we fabricated a uniform and periodic submicron perovskite subwavelength grating (SWG) absorber with broadband absorption and nanoscale precision. Our results demonstrate the use of FIB as a submicron patterning tool and a means of providing surface treatment (after FIB patterning to minimize optical loss) for perovskite photonic nanostructures. The SWG absorber can be patterned on perovskite solar cells to enhance the device efficiency through increasing light trapping and absorption.

  9. Enhanced Etching, Surface Damage Recovery, and Submicron Patterning of Hybrid Perovskites using a Chemically Gas-Assisted Focused-Ion Beam for Subwavelength Grating Photonic Applications

    KAUST Repository

    Alias, Mohd Sharizal Bin

    2015-12-22

    The high optical gain and absorption of organic–inorganic hybrid perovskites have attracted attention for photonic device applications. However, owing to the sensitivity of organic moieties to solvents and temperature, device processing is challenging, particularly for patterning. Here, we report the direct patterning of perovskites using chemically gas-assisted focused-ion beam (GAFIB) etching with XeF2 and I2 precursors. We demonstrate etching enhancement in addition to controllability and marginal surface damage compared to focused-ion beam (FIB) etching without precursors. Utilizing the GAFIB etching, we fabricated a uniform and periodic submicron perovskite subwavelength grating (SWG) absorber with broadband absorption and nanoscale precision. Our results demonstrate the use of FIB as a submicron patterning tool and a means of providing surface treatment (after FIB patterning to minimize optical loss) for perovskite photonic nanostructures. The SWG absorber can be patterned on perovskite solar cells to enhance the device efficiency through increasing light trapping and absorption.

  10. Study on the role of laser surface irradiation on damage and decohesion of Al/epoxy joints

    KAUST Repository

    Alfano, Marco

    2012-12-01

    In this work we investigate the effect of laser irradiation on the bond toughness of aluminum/epoxy bonded joints. The evolution of substrate surface morphology and wettability, for various sets of laser process parameters (i.e. laser power, line spacing, scan speed), was investigated by means of Scanning Electron Microscopy (SEM) and contact angle measurements. A proper combination of power, line spacing and scan speed was then selected and adhesive bonded Al/epoxy T-peel joints were prepared and tested. For comparison, similar samples were produced using substrates with classical grit blasting surface treatment. Finally, post-failure SEM analyses of fracture surfaces were performed, and in order to typify the increase in bond toughness of the joints, finite element simulations were carried out using a potential based cohesive zone model of fracture. © 2012 Elsevier Ltd.

  11. A bioluminescence ATP assay for estimating surface hydrophobicity and membrane damage of Escherichia coli cells treated with pulsed electric fields

    Science.gov (United States)

    Pulse Electric Field (PEF) treatments, a non-thermal process have been reported to injure and inactivate bacteria in liquid foods. However, the effect of this treatment on bacterial cell surface charge and hydrophobicity has not been investigated. Apple juice (AJ, pH 3.8) purchased from a wholesale ...

  12. Correlation between surface damage and micro-defects in Si covered with insulating layer by implantation of He and H ions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.L., E-mail: liuchanglong@tju.edu.c [School of Science, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Low Dimension Materials Physics and Preparing Technology, Institute of Advanced Materials Physics Faculty of Science, Tianjin 300072 (China); Li, M.K.; Wang, Z.; Gao, Y.J.; Liao, J.Q.; Zhang, D.C.; Zhang, X.L.; Shen, Y.Y. [School of Science, Tianjin University, Tianjin 300072 (China)

    2011-03-01

    Cz n-type Si (100) wafers covered with a 220 nm SiO{sub 2} layer or a 170 nm Si{sub 3}N{sub 4} layer were singly implanted with 160 keV He ions at a dose of 5 x 10{sup 16}/cm{sup 2} or successively implanted with 160 keV He ions at a dose of 5 x 10{sup 16}/cm{sup 2} and 110 keV H ions at a dose of 1 x 10{sup 16}/cm{sup 2}. Surface morphologies together with defect microstructures have been studied by means of several techniques, including optical microscopy, atomic force microscopy, and cross-sectional transmission electron microscopy (XTEM). Only surface blistering has been observed for He and H sequentially implanted SiO{sub 2}/Si samples after annealing in temperature range up to 1000 {sup o}C. However, as for the He and H implanted Si{sub 3}N{sub 4}/Si samples, surface features including blistering and the localized exfoliation of both the top Si{sub 3}N{sub 4} layer and the implanted Si layer have been well demonstrated during subsequent annealing. XTEM observations reveal quite different defect morphologies in two kinds of materials under the same implantation and annealing conditions. The possible mechanisms of surface damage in two kinds of materials have been discussed and presented based on the XTEM results.

  13. 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)

    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/cm2, 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)

  14. Correlation between surface damage and mechanical properties at micro- and nanometric length scale for WC-Co hardmetals

    OpenAIRE

    Canals Pou, Alberto María

    2014-01-01

    Cemented carbides (WC-Co) are ceramic-metal composite materials made by hard tungsten carbide particles bonded through a metallic binder matrix, mainly of cobalt. It is a hard material characterized by an exceptional combination of strength, toughness and wear resistance. As result, cemented carbides are first choice materials for cutting tools and wear parts. However, final shaping of these components usually require diamond grinding. During this hard machining, surface integrity may became ...

  15. A Pressure Simulating System Design for Semi-Physical Simulation of Aero-Engine Control System%航空发动机半物理仿真平台中压力模拟系统的设计

    Institute of Scientific and Technical Information of China (English)

    王登; 黄向华; 张天宏

    2012-01-01

    A design of pressure simulating system used in semi-physical simulation of aero-engine control system is brought forward. Via utilizing the electrohydraulic servocomponent as driving device, taking TMS320F2808 to process data, and adapting a gain-variable PID controller, this system responds fast and stably, and can simulate the variable pressure signal according to the variable given instructions. Thus the aero-engine control system can receive signals of the real pressure sensor instead of an electronic simulator. The design will contribute to the research of aero-engine control system especially to the pressure ratio control.%介绍了航空发动机控制系统半物理仿真平台中压力模拟系统的设计.系统采用电液伺服元件作为驱动装置、TMS32012808芯片以及可变增益的PID控制算法进行数据处理.其响应快速、稳定,能根据给定指令模拟出压力信号的变化,可以代替电路仿真信号给发动机控制系统以真实的压力传感器信号激励,在航空发动机控制系统尤其是压比控制的研究中将产生效益.

  16. 模拟平衡工艺方法在新一代航空发动机转子动平衡中的应用%Application of Analog Balancing Process for New Generation Aeroengine Rotor Dynamic Balancing

    Institute of Scientific and Technical Information of China (English)

    刘丛辉; 王娜; 陈玲玲

    2012-01-01

    The theory of analog balancing which breaks the general principle of dynamic balancing of aeroengine rotors is introduced. To illuminate this theory, with the trend of quick assembly modular construction of new generation aeroengine, the new method of rotor balancing, called analog balancing process is focused on. For the application of analog balancing process, exploratory research and experiments, design of analog balancing rotor, choice of balancing device, and the instances and effects analysis of analog balancing process technology application for new generation aeroengine rotors dynamic balancing in Liming company are introduced.%本文打破了常规航空发动机转子动平衡界律,从模拟平衡的原理入手,重点论述了新一代航空发动机转子动平衡的新工艺方法——模拟平衡法.介绍了模拟平衡转子的设计、模拟平衡工艺方法的设计、模拟平衡设备的选择及模拟平衡工艺技术的应用与效果分析.

  17. 商用航空发动机盘轴类转动件焊接工艺分析%Welding Process Analysis of Disk and Shaft Rotor Component of Commercial Aeroengine

    Institute of Scientific and Technical Information of China (English)

    张露; 韩秀峰; 王伦

    2015-01-01

    盘轴类转动件作为商用航空发动机的关键重要部件,且为限寿件,直接决定了商用航空发动机的可靠性和成本。随着焊接技术的发展,先进商用航空发动机盘轴类转动件越来越多地采用焊接工艺来代替螺栓连接,以减轻结构重量并提高其可靠性。目前,电子束焊和惯性摩擦焊作为主要焊接方法,在商用航空发动机盘轴类转动件的焊接中发挥着越来越重要的作用。%As crucial, important and life limited components, disk and shaft rotor components determine the reliability and cost of commercial aeroengine directly. With the developing of welding process, it has been used more often instead of bolts to join disk and shaft rotor components in advanced commercial aeroengine, in order to reduce weight and improve reliability. At present, as main welding methods, electron beam welding and inertia welding are playing more and more important role in join-ing disk and shaft rotor components of commercial aeroen-gine.

  18. Evaluation of the radiation damage of the reactor pressure vessel at Loviisa 1 using samples taken from the outer surface

    International Nuclear Information System (INIS)

    During the refuelling outage of Loviisa Unit 1 in 1993 four base material samples were taken from the outer surface of the reactor pressure vessel. The samples were taken from two beltline ring forgings. Two of the samples have so far been investigated by carrying out mechanical tests and microscopic, SEM, TEM and FEGSTEM analyses. Chemical composition and neutron fluence of the samples were also determined. Subsize KLST specimens of 3 x 4 x 27 mm were used for impact test. A well-established correlation was used to convert these impact test results into full-size Charpy impact values. Based on the experimental results the following conclusions can be drawn. The base material used in the Loviisa 1 surveillance program represents well the actual pressure vessel material. The results showed that the fluence of the pressure vessel outer surface and the transition temperature shift of the base material can be accurately predicted. The operation life of the Loviisa 1 RPV is not limited by irradiation embrittlement of the base material. (author). 2 refs, 3 tabs, 4 pictures

  19. 发动机榫头/榫槽接触问题的可靠性形状优化设计%Reliability-Based Shape Optimization of Tenon/Mortise in Aero-engines with Contact

    Institute of Scientific and Technical Information of China (English)

    崔海涛; 马海全; 温卫东

    2003-01-01

    Based on the theory of reliability-based structural shape optimization, exact expressions of the sensibility using the stochastic finite element method for contact problems were derived in detail, and the basic steps of structural optimization were given. A coattail-type tenon/mortise of an aero-engine was optimized. In this model, the maximum equivalent stress of the nodes on the boundary of the tenon was the objective function; the width of tooth's neck and the side surface's slope angle of a tenon were design variables, with constraints of tension stress, extrusion stress and reliability index. The result showed that the distributions of the contact pressure between tenon and mortise, the equivalence stress and reliability index were more reasonable. It validates the correctness of the optimization model and the reliability-based structural shape optimization, and provides valuable references for structural design of the tenon/mortise.%在结构可靠性形状优化的基础上,推导了接触问题随机有限元的灵敏度解析分析表达式,给出了优化分析的基本步骤,并对某发动机燕尾型榫头/榫槽接触结构,选取榫头齿颈宽和齿面倾斜角为设计变量,以榫头最大拉伸应力、齿面挤压应力及可靠度指标为约束条件,对榫头边界上节点的最大当量应力进行了优化分析.结果表明,优化后榫头和榫槽接触面上的接触压力、当量应力及可靠度指标的分布更加均匀,验证了优化分析模型的合理性及所提出的可靠性形状优化设计方法的有效性,为榫头/榫槽的结构设计提供有价值的参考.

  20. 高陡度非球面磨削亚表面损伤深度规律%Subsurface damage rule of deep aspheric surface by grinding

    Institute of Scientific and Technical Information of China (English)

    朱登超; 戴一帆; 关朝亮; 王贵林

    2015-01-01

    Deep aspheric optical element can obviously improve the aerodynamic performance of the optical system,thus enhancing and optimizing the comprehensive performance of optical system.The grinding method can be used for primary machining of such elements.However, subsurface damage will be inevitably introduced by this method,and grinding parameters will be changing in real time in the processing of deep aspheric surface,so the depths of subsurface damage of the workpiece are inconsistent.In view of this situation,subsurface damage prediction model was established.Combined with the characteristics of semi-sphere wheels grinding,a theoretical calculation was made to predict distributive regularity of the aspheric grinding subsurface damage depths aspheric characteristics.On the basis of the above work,a simulation experiment on hot-pressing polycrystalline magnesium fluoride plane was carried out.Subsurface damage depths under different conditions of grinding parameters were acquired by the method of magnetorheological finishing spot.Results show that the depth range is between 12.79μm and 20.96μm,which increases from inside to outside along the radius of the workpiece and the results are coincide with previous forecast model.%具有高陡度非球面特性的光学元件可以明显改善光学系统的空气动力学性能,从而提升和优化系统综合性能。磨削加工方法可以作为此类元件的前期加工工序,而磨削难免会造成零件的亚表面损伤,且在这种高陡度非球面磨削加工中磨削参数是实时变化的,造成整个工件亚表面损伤深度不一致。针对这种情况,建立亚表面损伤预测模型,并结合半球形砂轮磨削的特点,通过理论计算预测非球面磨削亚表面损伤深度分布规律。在此基础上,以热压多晶氟化镁平面为对象进行模拟参数实验,通过磁流变抛斑点法得到各组参数下亚表面损伤深度情况,结

  1. Structured Modeling of Aeroengine Assembly Data and Its Application%航空发动机装配数据结构化建模及应用

    Institute of Scientific and Technical Information of China (English)

    李坤; 莫蓉

    2014-01-01

    Aeroengine assembly data is low degree of structure and data tracing back was dififcult. In order to deal with these problems, areoengine assembly data structure and features is analyzed. Deifnition model of assembly production preparation data and assembly pro-duction process data is proposed. Data model based on as-sembly structured data units is established. The generation process of electronic curriculum vitae is presented. Appli-cation example veriifed the effectiveness of this method.%针对航空发动机装配数据结构化程度低及数据追溯困难等问题,分析了航空发动机装配数据构成及特点,提出了一个装配生产准备数据和装配生产过程数据的定义模型。针对装配生产过程数据特点,建立了以装配数据单元为核心的装配数据模型,给出了电子化履历本的实现过程,验证了方法的有效性。

  2. Shot-peened Residual Stress of Aeroengine Titanium Alloy Blades%航空发动机钛合金叶片喷丸强化残余应力研究

    Institute of Scientific and Technical Information of China (English)

    张彩珍; 杨健; 魏磊; 李跃辉; 吕建勋; 陈林洪

    2016-01-01

    Objective The residual stress field of aeroengine titanium alloy blades was studied, and the residual stress distribu-tion of blades after shot peening and after use was mastered, in order to provide a basis for evaluating the safety and reliability of the blades, and to provide data support for predicting the residual life of the blades. Methods The surface residual stress field after shot peening, the residual stress distribution along the deep layer, and the residual stress of aeroengine fan blades and compressor blades after use were studied using X-ray diffraction technology. Results After shot peening, about 90% of residual stress of the fan blades was distributed in the range of -600~-800 MPa, and the average residual stress value was about -682 MPa. About 90% of residual stress distribution of the compressor blades was distributed in the range of-500~-700 MPa, and the average re-sidual stress was about -603 MPa. After shot peening, the surface residual stress of the fan blade and compressor blade was about-610 MPa, and there was a maximum residual stress in the subsurface layer, the values were-739 MPa at 11μm and-683 MPa at 13μm, respectively, and then the residual stress decreased gradually with increasing depth. The residual stress distribution of the fan blades was-460~-720 MPa after using for 300 hours, and-430~-700 MPa after using for 600 hours. The residual stress distribu-tion of the compressor blades was-470~-670 MPa after using for 300 hours, and-360~-620 MPa after using for 600 hours. Con-clusion The residual compressive stress of Titanium alloy blade after shot peening first decreased and then increased with the increase of the layer depth, and the depth of the residual stress field was about 50 μm. The residual stress of titanium alloy blade after use showed an attenuation trend, and the residual compressive stress attenuation increased gradually with the increase of using time.%目的 研究航空发动机钛合金叶片残余应力场,掌

  3. Modeling Cryptosporidium and Giardia in Ground and Surface Water Sources in Rural India: Associations with Latrines, Livestock, Damaged Wells, and Rainfall Patterns.

    Science.gov (United States)

    Daniels, Miles E; Smith, Woutrina A; Schmidt, Wolf-Peter; Clasen, Thomas; Jenkins, Marion W

    2016-07-19

    Surface and groundwater contamination with fecal pathogens is a public health concern especially in low-income settings where these sources are used untreated. We modeled observed Cryptosporidium and Giardia contamination in community ponds (n = 94; 79% contaminated), deep tubewells (DTWs) (n = 107; 17%), and shallow tubewells (STWs) (n = 96; 19%) during the 2012 and 2013 monsoon seasons (June-August) in 60 villages in Puri District, India to understand sources and processes of contamination. Detection of Cryptosporidium and/or Giardia in a tubewell was positively associated with damage to the well pad for DTWs, the amount of human loading into pour-flush latrine pits nearby (≤15 m) for STWs, and the village literacy rate (for Giardia in STWs). Pond concentration levels were positively associated with the number of people practicing open defecation within 50 m and the sheep population for Cryptosporidium, and with the village illiteracy rate for Giardia. Recent rainfall increased the risk of Cryptosporidium in STWs (an extreme event) and ponds (any), while increasing seasonal rainfall decreased the risk of Giardia in STWs and ponds. Full latrine coverage in this setting is expected to marginally reduce pond Cryptosporidium contamination (16%) while increasing local groundwater protozoal contamination (87-306%), with the largest increases predicted for Cryptosporidium in STWs. PMID:27310009

  4. Modeling Cryptosporidium and Giardia in Ground and Surface Water Sources in Rural India: Associations with Latrines, Livestock, Damaged Wells, and Rainfall Patterns.

    Science.gov (United States)

    Daniels, Miles E; Smith, Woutrina A; Schmidt, Wolf-Peter; Clasen, Thomas; Jenkins, Marion W

    2016-07-19

    Surface and groundwater contamination with fecal pathogens is a public health concern especially in low-income settings where these sources are used untreated. We modeled observed Cryptosporidium and Giardia contamination in community ponds (n = 94; 79% contaminated), deep tubewells (DTWs) (n = 107; 17%), and shallow tubewells (STWs) (n = 96; 19%) during the 2012 and 2013 monsoon seasons (June-August) in 60 villages in Puri District, India to understand sources and processes of contamination. Detection of Cryptosporidium and/or Giardia in a tubewell was positively associated with damage to the well pad for DTWs, the amount of human loading into pour-flush latrine pits nearby (≤15 m) for STWs, and the village literacy rate (for Giardia in STWs). Pond concentration levels were positively associated with the number of people practicing open defecation within 50 m and the sheep population for Cryptosporidium, and with the village illiteracy rate for Giardia. Recent rainfall increased the risk of Cryptosporidium in STWs (an extreme event) and ponds (any), while increasing seasonal rainfall decreased the risk of Giardia in STWs and ponds. Full latrine coverage in this setting is expected to marginally reduce pond Cryptosporidium contamination (16%) while increasing local groundwater protozoal contamination (87-306%), with the largest increases predicted for Cryptosporidium in STWs.

  5. Earthquake damage to underground facilities

    International Nuclear Information System (INIS)

    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

  6. Sun Damage

    Science.gov (United States)

    ... rash and rashes clinical tools newsletter | contact Share | Sun Damage A A A The sun has a profound effect over years of exposure ... changes. Exposure to ultraviolet (UV) light from the sun accounts for most premature skin aging. Many skin ...

  7. 瓷绝缘子表面激光损伤的数值模拟和实验研究%Numerical simulation and experiment research of laser damage of porcelain insulator surface

    Institute of Scientific and Technical Information of China (English)

    齐丽君; 朱晓; 朱长虹; 郭飞; 朱广志; 谷山强

    2011-01-01

    During the process of laser de-icing applied in the electric grid, the electrical equipment such as insulator should not be damaged by the laser. The temperature and stress field distributions of normal porcelain, alumina porcelain, zirconium oxide porcelain and cordierite porcelain after laser irradiating are obtained by using ANSYS software. The results show that alumina porcelain has advantages in characteristics of anti-damage of thermal induced stress. The experiments of surface damage of insulator with Nd: YAG laser irradiation are explored. The relations between surface temperature and irradiating time are obtained. So is the damage form. Numerical analysis and experiment results are both show that laser power density and irradiating time are considered as the important influence factors of laser damage of the insulator. Thermal damage and thermal-stress damage are the main types of laser damage of porcelain insulator, which are related to the surface temperature after laser irradiation. The anti-damage methods of aiming and controlling, combining laser de-icing with other de-icing methods to protect the insulator are also proposed.%为了防止输电线路激光除冰过程中激光损伤绝缘子等电力设备,采用有限元分析软件ANSYS对激光与普通瓷、氧化铝瓷、氧化锆瓷、堇青石瓷作用后的温度场和应力场进行了数值模拟,得到氧化铝瓷具有较好的抗热应力破坏性能,并进行了Nd∶ YAG激光照射绝缘子表面实验,得到绝缘子表面温度与照射时间和损伤类型的关系.结果表明,激光功率密度和照射时间是影响绝缘子破坏的重要因素,瓷绝缘子表面损伤包括热损伤和热应力破坏,破坏类型与表面温度相关.提出了瞄准、控制、激光除冰与其它除冰方式相结合等保护措施.这一结果对输电线路激光除冰工程应用中保障电力设施的安全是有帮助的.

  8. Damage Distributions

    DEFF Research Database (Denmark)

    Lützen, Marie

    2001-01-01

    The purpose of Task 2.2 of the HARDER project is according to the work package description: For various structural configurations of the struck ship and using the results of Task 2.1, the probability distributions for the damage location and size will be derived. The format will be similar to the...... damage statistics and bow height statistics for vessels in the world fleet. The proposals for the p-, r-, and v-factors have been compared to factors from current regulation by examples.......The purpose of Task 2.2 of the HARDER project is according to the work package description: For various structural configurations of the struck ship and using the results of Task 2.1, the probability distributions for the damage location and size will be derived. The format will be similar to the p...... between the damage location, the damage sizes and the main particulars of the struck vessel. From the numerical simulation and the analyse of the damage statistics it is found that the current formulation from the IMO SLF 43/3/2 can be used as basis for determination of the p-, r-, and v...

  9. Linear Quadratic Optimal Control for Aeroengine%航空发动机线性二次型最优控制

    Institute of Scientific and Technical Information of China (English)

    刘海堂; 吕伟; 喻鸣; 毛宁

    2012-01-01

    With the increase of the control variables, the aero-engine has been the object of a single variable to multivariable in multivariable feedback control system design method. The linear quadratic optimal control method is presented due to the infinite gain margin and greater than 60 ° phase margin and much attention. In Matlab to create a model of controlled object, for engine dynamic parameters within the flight envelope changes, significant uncertainties, an optimal control method based on optimization theory, design of the LQR controllers with excellent performance, reasonable control energy advantages: linear simulation and nonlinear hardware in the loop simulation are verified by this method designed controller has good performance.%随着控制变量的增多,航空发动机已由单变量对象发展为多变量对象.在多变量反馈控制系统设计方法中,线性二次型最优控制方法由于具有无穷大的幅值裕度和大于60.的相位裕度而倍受人们的关注.在Matlab下以建立的模型作为被控对象,针对发动机在飞行包线范围内动态参数变化大、不确定因素显著的情况,提出了一种基于优化理论的最优控制方法.设计出的LQR控制器具有性能优良、控制能量合理的优点.通过线性仿真和非线性硬件在回路模拟试验,均验证了按此方法设计的控制器具有良好的性能.

  10. 基于边沿像素定位的金属表面破损视觉检测算法%Metal Surface Damage Visual Detection Algorithm Based on the Edge Pixel Positioning

    Institute of Scientific and Technical Information of China (English)

    樊雄

    2013-01-01

    Use pixel segmentation algorithm for metal surface damage visual inspection, in image acquisition process will be affected by acquisition space illumination condition the influence, will cause the metal surface pixel displacement of defects, resulting in a decrease in accuracy detection. Therefore, this paper proposes a based on the edge pixel localization algorithm of metal surface damage visual inspection method. Acquisition metal surface image, using the method of edge pixels ChanJiHua were extracted and through the edge pixel location method to calculate the edge pixel space position, so as to realize the metal surface damage visual inspection. Experiments show that this algorithm can effectively improve the metal surface damage visual inspection accuracy, and achieved satisfactory results.%利用像素分割算法进行金属表面破损视觉检测,在图像采集的过程中会受到采集空间光照条件的影响,将造成金属表面像素错位的缺陷,从而导致检测准确性降低.为此,提出了一种基于边沿像素定位算法的金属表面破损视觉检测方法.采集金属表面图像,利用单极化方法对边沿像素进行提取,通过边沿像素定位方法计算边沿像素的空间位置,从而实现金属表面破损视觉检测.实验证明,这种算法能够有效提高金属表面破损视觉检测的准确性,取得了令人满意的结果.

  11. Ocular surface damage of Graves disease patients without eye symptoms%无眼征Graves病患者的眼表损害

    Institute of Scientific and Technical Information of China (English)

    张磊; 何彦津

    2012-01-01

    Objective To evaluate the ocular surface damage and the changes of tear film function in Graves disease ( GD) patients without eye symptoms, and investigate the function of ocular inflammation in the pathogenesis of dry eye. Methods A total of 38 patients(76 eyes) with GD without eye symptoms and 30 healthy controls(60 eyes) were included in this study. The palpebral fissure height,degree of proptosis, ocular surface disease index(OSDI) ,Schirmer I tear test,break-up time(BUT) ,corneal fluorescence staining (FL) , and conjunctival impression cytology (IC) were assessed. The results were compared between the patient and the control groups. Results The OS-DI score was 43. 34 ± 10. 32 in the GD group and 22. 56 ±11.21 in the control group, there was significant difference (P < 0. 01). The value of Schirmer I test was (13.2 ± 7.1) mm in the GD group and (22.4 ± 4. 5) mm in the control group, there was significant difference^<0.01). BUT was(7.2±2. l)s in the GD group and( 10. 4 ±2. 9)s in the control group,there was significant difference(P < 0. 01). In the cornea! fluorescence staining test,20 eyes were positive in the GD group and 6 eyes in the control group, there was statistical difference(P = 0.016). Conjunctival impress cytology showed grade 0 was in 26 eyes(36.11% ),grade 1 in 23 eyes(31.94% ),grade 2 in 17 eyes(23.61% ), grade 3 in 6 eyes(8. 33% ) in GD group,whereas grade 0 in 39 eyes(65.00% ) .grade 1 in 13 eyes(21. 67% ), grade 2 in 6 eyes ( 10. 00% ), grade 3 in 2 eyes ( 3. 33% ) in control group,there was significant difference(P=0. 008). There was no statistical difference in interpalpebral distance and protosis between two groups( t = 0.482, -0.357 ;P = 0.632,0.723). Conclusion Dry eye and ocular surface damage appear in GD without eye symptoms, which may be associated with the ocular surface inflammation.%目的 评价无眼征的Graves病(Graves disease,GD)患者的眼表损害以及泪膜功能变化,了解眼表炎症在干眼

  12. CB N砂轮在航空发动机零件高效精密加工中的应用%Application of CBN grinding wheels in high efficiency and precision grinding for aero-engine parts

    Institute of Scientific and Technical Information of China (English)

    闫宁; 李学文; 赵盟月; 杨威; 邵俊勇; 孙鹏辉

    2015-01-01

    This article analyzed the characteristics and current status of the grinding processing for aero-engine parts,summarized the research developments of grinding wheels in high-efficiency and precision grinding for aviation field,introduced the technical breakthrough of cubic boron nitride(CBN)grinding wheels manufacture,indicated that CBN grinding wheels have wide application prospect in high-efficiency and precision grinding for aero-engine parts,and raised existing problems when promoting this application.%分析了航空发动机零件磨削加工的特点及现状,综述了砂轮在航空领域高效精密磨削中的研究进展,介绍了 CBN 砂轮制备技术的突破,指出了 CBN 砂轮在航空发动机零件的高效精密加工中具有广阔的应用前景,并提出了推广应用中存在的问题。

  13. Radiation damage

    CERN Document Server

    Heijne, Erik H M; CERN. Geneva

    1998-01-01

    a) Radiation damage in organic materials. This series of lectures will give an overview of radiation effects on materials and components frequently used in accelerator engineering and experiments. Basic degradation phenomena will be presented for organic materials with comprehensive damage threshold doses for commonly used rubbers, thermoplastics, thermosets and composite materials. Some indications will be given for glass, scintillators and optical fibres. b) Radiation effects in semiconductor materials and devices. The major part of the time will be devoted to treat radiation effects in semiconductor sensors and the associated electronics, in particular displacement damage, interface and single event phenomena. Evaluation methods and practical aspects will be shown. Strategies will be developed for the survival of the materials under the expected environmental conditions of the LHC machine and detectors. I will describe profound revolution in our understanding of black holes and their relation to quantum me...

  14. Convergence Analysis of the Numerical Solution for Cathode Design of Aero-engine Blades in Electrochemical Machining

    Institute of Scientific and Technical Information of China (English)

    Li Zhiyong; Niu Zongwei

    2007-01-01

    As a main difficult problem encountered in electrochemical machining (ECM), the cathode design is tackled, at present, with various numerical analysis methods such as finite difference, finite element and boundary element methods. Among them, the finite element method presents more flexibility to deal with the irregularly shaped workpieces. However, it is very difficult to ensure the convergence of finite element numerical approach. This paper proposes an accurate model and a finite element numerical approach of cathode design based on the potential distribution in inter-electrode gap. In order to ensure the convergence of finite element numerical approach and increase the accuracy in cathode design, the cathode shape should be iterated to eliminate the design errors in computational process. Several experiments are conducted to verify the macbining accuracy of the designed cathode. The experimental results have proven perfect convergence and good computing accuracy of the proposed finite element numerical approach by the high surface quality and dimensional accuracy of the machined blades.

  15. 神经网络和卡尔曼滤波融合的航空发动机传感器故障诊断%Neural Network and Kalman Filter Based Fusion Fault Diagnosis for Aeroengine Sensor

    Institute of Scientific and Technical Information of China (English)

    尹俊; 郭迎清

    2011-01-01

    为提高航空发动机传感器故障诊断的准确率和可靠性,使用改良的D-S证据理论,对基于神经网络和卡尔曼滤波的2个诊断子系统的诊断结果进行决策融合;仿真结果显示,在发动机稳定状态下,经过融合,整个系统降低了误诊率,改善了诊断性能;文章还针对加强噪声强度的情况下,通过调整2个子系统的权重,在保证准确率的同时提高了系统的抗噪声性能;研究表明D-S理论可以比单独应用单一诊断算法的子系统更具好的诊断效能.%In order to improve accuracy and reliability of aeroengine sensors fault diagnosis. In this paper Dempster-Shatter theory is used to build a new diagnosis system by blending and tuning the output of BP neural network based diagnosis sub-system and that of kalman filter based sub-system. In the engine steady state, test results show that the system can diagnose and detect the faults of aeroengine sen-sors with more precision and efficiency than either single sub-system. In adiition. This new D-S theory and two nerual network and kal-man filter based diagnosis system can be used to obtain better ability of rejecting noise than the two sub- systems, wih adjusting the weights of the diagnosis decisions of two sub-systems.

  16. Method for producing damage resistant optics

    Science.gov (United States)

    Hackel, Lloyd A.; Burnham, Alan K.; Penetrante, Bernardino M.; Brusasco, Raymond M.; Wegner, Paul J.; Hrubesh, Lawrence W.; Kozlowski, Mark R.; Feit, Michael D.

    2003-01-01

    The present invention provides a system that mitigates the growth of surface damage in an optic. Damage to the optic is minimally initiated. In an embodiment of the invention, damage sites in the optic are initiated, located, and then treated to stop the growth of the damage sites. The step of initiating damage sites in the optic includes a scan of the optic using a laser to initiate defects. The exact positions of the initiated sites are identified. A mitigation process is performed that locally or globally removes the cause of subsequent growth of the damaged sites.

  17. 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.

  18. PCA algorithm for detection, localisation and evolution of damages in gearbox bearings

    Energy Technology Data Exchange (ETDEWEB)

    Pirra, M; Gandino, E; Garibaldi, L; Machorro-Lopez, J M [Dipartimento di Meccanica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Torri, A, E-mail: luigi.garibaldi@polito.it [Avio S.p.A., Strada del Drosso 145, 10135 Torino (Italy)

    2011-07-19

    A fundamental aspect when dealing with rolling element bearings, which often represent a key component in rotating machineries, consists in correctly identifying a degraded behaviour of a bearing with a reasonable level of confidence. This is one of the main requirements a health and usage monitoring system (HUMS) should have. This paper introduces a monitoring technique for the diagnosis of bearing faults based on Principal Component Analysis (PCA). This method overcomes the problem of acquiring data under different environmental conditions (hardly biasing the data) and allows accurate damage recognition, also assuring a rather low number of False Alarms (FA). In addition, a novel criterion is proposed in order to isolate the area in which the faulty bearing stands. Another useful feature of this PCA-based method concerns the capability to observe an increasing trend in the evolution of bearing degradation. The described technique is tested on an industrial rig (designed by Avio S.p.A.), consisting of a full size aeroengine gearbox. Healthy and variously damaged bearings, such as with an inner or rolling element fault, are set up and vibration signals are collected and processed in order to properly detect a fault. Finally, data collected from a test rig assembled by the Dynamics and Identification Research Group (DIRG) are used to demonstrate that the proposed method is able to correctly detect and to classify different levels of the same type of fault and also to localise it.

  19. 表面颗粒污染物诱导薄光学元件初始损伤的机理*%Mechanism of original damage of thin optical comp onents induced by surface particle contamination

    Institute of Scientific and Technical Information of China (English)

    孙晓艳; 雷泽民; 卢兴强; 范滇元

    2014-01-01

    基于光传输理论研究了前表面颗粒污染物诱导薄光学元件产生初始损伤的原因,提出了颗粒遮光效应和颗粒造成的光学元件局部热变形两者共同作用对光束进行扰动的损伤机理。研究结果表明:对于高功率激光光束,薄光学元件局部热变形对光束的扰动是产生较高光强调制的重要原因;随着激光脉冲发射次数的增加,局部热变形的表面形状、位相延迟幅度、热扩散长度不断变化,会在光学元件内不同厚度处和后表面xy方向上的不同位置处产生较高的光强调制,不仅容易引起后表面产生多个损伤点,也可能在光学元件内就产生损伤,并且在厚度方向上的损伤点是分散的。%Based on the optical transmission theory, the reason why front-surface particle contamination may induce the original damage of thin optical components is considered, and a damage mechanism is put forward: The localized thermal deformation of an optical element induced by the thermal effect of particle contamination together with the shading effect of it can disturb the laser beams. Simulated results show that for a high power laser, the localized thermal deformation of thin optical components, which disturbs the laser beam, is an important cause to produce strong light intensity modulations. The surface shape, phase delay, and thermal diffusion length of a localized thermal deformation are constantly changing with the increase of laser pulse shot number, so the highest light intensity modulation will be produced at different positions in the thickness direction or the xy direction on the rear-surface of an optical element. This not only can easily induce some damages on the rear-surface of the optical element, but also cause the interior damages scattered in the thickness direction.

  20. Radiation damage tolerant nanomaterials

    Directory of Open Access Journals (Sweden)

    I.J. Beyerlein

    2013-11-01

    Full Text Available Designing a material from the atomic level to achieve a tailored response in extreme conditions is a grand challenge in materials research. Nanostructured metals and composites provide a path to this goal because they contain interfaces that attract, absorb and annihilate point and line defects. These interfaces recover and control defects produced in materials subjected to extremes of displacement damage, impurity implantation, stress and temperature. Controlling radiation-induced-defects via interfaces is shown to be the key factor in reducing the damage and imparting stability in certain nanomaterials under conditions where bulk materials exhibit void swelling and/or embrittlement. We review the recovery of radiation-induced point defects at free surfaces and grain boundaries and stabilization of helium bubbles at interphase boundaries and present an approach for processing bulk nanocomposites containing interfaces that are stable under irradiation.

  1. Uneven damage on head and liner contact surfaces of a retrieved Co-Cr-based metal-on-metal hip joint bearing: An important reason for the high failure rate.

    Science.gov (United States)

    Koizumi, Yuichiro; Chen, Yan; Li, Yunping; Yamanaka, Kenta; Chiba, Akihiko; Tanaka, Shun-Ichiro; Hagiwara, Yoshihiro

    2016-05-01

    Detailed metallurgical investigations have been performed on a used Co-Cr-based metal-on-metal (MoM) hip joint bearing containing a type of liner that is commonly used in such joints. The damage on the metal-liner sliding surface was considerably more severe than that on the metal head counterpart, in terms of wear-scar density and width and microcrack frequency. Cross-sectional transmission electron microscopy revealed that a thick (>3 μm) nanocrystalline layer formed on the sliding surface of the head, whereas the liner had coarse carbides embedded in it and nanocrystals were formed in a very limited region no deeper than 1 μm. Comparative investigation of an unused head and a liner of identical type showed that although the chemical compositions of the liner and head were nearly identical, their microstructures were significantly different. Specifically, the grain size in the liner was larger than that in the head on average, and the grain boundaries of the liner were decorated with coarse carbides. Moreover, X-ray diffraction analysis revealed a large tensile residual stress only in the liner. These differences are possibly responsible for the wear damage on the liner being more serious than that on the head. PMID:26952456

  2. substantiation of nuclear safety ensuring for storing LWR cores, including damaged ones, in NPP of Russian out of service nuclear powered submarines, surface ships and vessels

    International Nuclear Information System (INIS)

    A lot of Russian nuclear ships and vessels, first nuclear powered submarines (NPS) with light water coolant are out of service and non-defueled. The critical economic situation in Russia doesn't allow solving this problem for the tolerable run. The nuclear and radiation safety of such cores long-term storage in the ships and vessels afloat must be ensured. The other serious problem to be tackled by nuclear experts and organizations is the mooring of NPS with accident nuclear powered plants (NPP). The damaged cores should be explored, and their nuclear safety must be ultimately enhanced. The protection of the nearest and distant population and regions from the nuclear man-made hazards caused by the retired non-defueled floating NPS could be ensured by the draining of the core in reactor pressure vessels (RPV) and the filling of the core by heavy melt or pure liquid metal. A metal must possess the necessary nuclear and chemical properties, and thermal hydraulics conditions as well as the properties of the self-solidified in RPV the inert metal. The principal findings, especially the ship's reactor criticality reduction and the fixation of fuel elements in the RPV structure, are of great importance for the prevention of any emergency and the non-proliferation of high-enriched SNF from the naval reactors at the all stages of the handling with the in-RPV core. (author)

  3. Dissociative adsorption of molecular deuterium and thermal stability onto hydrogenated, bare and ion beam damaged poly- and single crystalline diamond surfaces

    Science.gov (United States)

    Michaelson, Sh.; Chandran, M.; Zalkind, S.; Shamir, N.; Akhvlediani, R.; Hoffman, A.

    2015-12-01

    In this work we report on dissociative adsorption of deuterium (D2) on bare, hydrogenated and ion beam bombarded polycrystalline and single crystalline diamond surfaces. Polycrystalline diamond films with an average grain size of ~ 300 nm were deposited on silicon substrates by hot filament chemical vapor deposition technique from methane/hydrogen gas mixture. Deposited films were characterized using Raman spectroscopy, atomic force microscopy and scanning electron microscopy to estimate the phase composition and microstructure. High resolution electron energy loss spectroscopy and direct recoil spectrometry were used to study hydrogen (deuterium) bonding configuration of the upper surface region. Near surface amorphization was achieved by 1 keV Ar+ implantation at ~ 1 × 1015 ions/cm2 at room temperature (RT). As deposited and Ar+ bombarded films are annealed to 500-1000 °C in ultra-high vacuum conditions and also under D2 partial pressure of 5 × 10- 6 Torr. For comparison, key experiments were repeated on the single crystal (100) diamond. Our results clearly show the preferential dissociative adsorption of D2 on low hybridized carbon (sp/sp2) states with activation temperature as low as RT, but with a lower thermal stability compared to pure diamond Csbnd D bonds.

  4. Damage-dependent bounding surface model for cyclic degradation of saturated clay%考虑循环载荷下饱和黏土软化的损伤边界面模型研究

    Institute of Scientific and Technical Information of China (English)

    胡存; 刘海笑; 黄维

    2012-01-01

    研究表明,循环载荷作用下饱和黏土将发生软化,其机制主要有两个:一是孔压的积累;二是土体原有结构的不断损伤和新结构的不断重塑.针对上述机制,基于广义各向同性硬化准则建立了考虑饱和黏土循环软化的损伤单面模型.该模型在有效应力空间中引入损伤变量,表征土体结构的损伤和重塑程度,在连续的循环加载下,损伤不断累积,边界面则随着损伤的累积不断收缩,以模拟饱和黏土刚度和强度的软化;以应力反向点作为边界面的广义各向同性硬化中心和映射法则的映射中心,灵活地选择塑性模量的插值公式以模拟塑性变形和孔压的累积以及应力-应变的滞回特性.应用该模型对不排水循环三轴试验进行模拟,并且考查了循环周次、循环应力水平和固结历史对饱和黏土循环软化特性的影响,并与相关试验比较,验证了模型的有效性.%Degradation of saturated clay during cyclic loading can be assumed to be caused mainly by two mechanisms, pore water pressure build-up and the damage and remolding of soil fabric. Based on these mechanisms, a damage-dependent bounding surface model for cyclic degradation of saturated clay is proposed using the generalized isotropic hardening rule. In the model, the degree of damage and remolding of soil during cyclic loading is quantified by introducing a damage variable and the size of the bounding surface decreases with damage accumulation to characterize progressive degradation and nonlinear behavior of the saturated clay. By taking the stress reversal point as the generalized isotropic hardening center of the bounding surface as well as the mapping origin, the forms of hardening modulus can be adopted flexibly so as to predict the accumulation of plasticity deformation and pore pressure and the hysteresis property of clay. The cyclic behaviors for undrained one-way cyclic triaxial tests are predicted by the model

  5. Abrupt fault diagnosis of aero-engine based on affinity propagation clustering%基于相似性传播聚类的航空发动机突发故障诊断

    Institute of Scientific and Technical Information of China (English)

    李丽敏; 王仲生; 姜洪开

    2014-01-01

    针对航空发动机突发故障,构建了一种基于相似性传播聚类的突发故障诊断方法。首先利用突发故障历史监测数据建立突发故障数据库,通过相似性传播聚类找到数据库中所有突发故障数据的中心,当诊断新采集数据的突发故障类型时,通过相似性传播聚类找到当前新采集数据的中心,经过与突发故障数据库中的数据中心进行匹配判断该新采集数据所对应的突发故障类型。将该突发故障诊断方法应用到发动机转子实验台的突发故障诊断中,仿真和实验结果表明该方法的可行性,并通过与其他方法比较,表明该方法具有诊断时间短和误差小的优点。%Aiming at aero-engine faults,an abrupt fault diagnosis method based on affinity propagation clustering was proposed.Abrupt fault historical monitoring data were used to establish faults database.Through affinity propagation clustering,all the exemplars of abrupt faults in the database were found and the affinity propagation clustering was applied once again to find the exemplar of the new collected data.The fault type was then identified by matching the center with the centers obtained from the faults database.The method was used in the aero-engine abrupt fault diagnosis.The simulation and experiment results show that the method is feasible to diagnose abrupt fault,and compared with other methods,it needs shorter time consuming and produces lower error.

  6. 航空发动机对转涡轮气动设计技术研究进展%Aerodynamic Design of Counter-rotating Turbine for Aero-engine

    Institute of Scientific and Technical Information of China (English)

    周琨; 邹正平; 刘火星; 王雷

    2012-01-01

    随着航空工业的发展,民用或者军用飞行器都对航空发动机要求越来越高,对转涡轮由于其气动布局上的优势能成为未来航空发动机的关键技术之一.本文通过对国内外文献的调研,结合课题组多年研究工作,分析了对转涡轮内部的特征,并从对转涡轮速度三角形参数分析和气动设计准则、内部复杂流动机制、激波组织技术和收扩叶型造型方法等方面对其研究进展进行了论述;在此基础上考虑加工工艺、结构强度、传热冷却等多学科耦合因素,探讨了转涡轮技术在工程应用中面临的挑战及可能的解决方向,展望了转涡轮技术的发展趋势.%With the development of aviation industry, more and more requirements are submitted during the design of civil and military aero-engines, such as higher thrust-weight ratio, lower fuel consumption, more affordability, etc. The counter-rotating turbine technology provides a powerful solution for the problems. The relevant literatures are reviewed from the aspects of velocity triangle parametric analyses, aerodynamic design criteria, internal (low mechanisms, Shockwave control methods, and design techniques of convergent-divergent airfoils, respectively. By combining literature review with the research carried out in many years by authors, the characteristics of counter-rotating turbine are analyzed. However some challenges are also encountered when the counter-rotation turbine technology is applied to the aero-engines. These challenges in terms of processing technology, structural strength, heal transfer/cooling as well as their possible solutions are considered. Finally, the development trends of the technology are predicted.

  7. FLOW PATTERNS AND DAMAGE OF DIKE OVERTOPPING

    Institute of Scientific and Technical Information of China (English)

    Chaiyuth CHINNARASRI; Tawatchai TINGSANCHALI; Sutat WEESAKUL; Somchai WONGWISES

    2003-01-01

    Damage of a dike may result in severe damage and suffering. To reduce downstream damage and loss of life, it is important to study the process of breaching of the damaged dike. It is not possible to understand the damage process without a clear understanding of the flow patterns encountered. In the present study, data obtained from nine experimental runs are analyzed. The flow patterns and progressive damage of dike overtopping are investigated. Two types of phenomena at the dike surface:erosion; and erosion and sliding, are observed during the overtopping event. Four stages of dike damage can be distinguished. The degradation rate of the dike crest is found to be dependent on the downstream slope of the dike. The degradation rate is higher when the downstream slope is steeper.

  8. A Model for Creep and Creep Damage in the γ-Titanium Aluminide Ti-45Al-2Mn-2Nb

    Directory of Open Access Journals (Sweden)

    William Harrison

    2014-03-01

    Full Text Available Gamma titanium aluminides (γ-TiAl display significantly improved high temperature mechanical properties over conventional titanium alloys. Due to their low densities, these alloys are increasingly becoming strong candidates to replace nickel-base superalloys in future gas turbine aeroengine components. To determine the safe operating life of such components, a good understanding of their creep properties is essential. Of particular importance to gas turbine component design is the ability to accurately predict the rate of accumulation of creep strain to ensure that excessive deformation does not occur during the component’s service life and to quantify the effects of creep on fatigue life. The theta (θ projection technique is an illustrative example of a creep curve method which has, in this paper, been utilised to accurately represent the creep behaviour of the γ-TiAl alloy Ti -45Al-2Mn-2Nb. Furthermore, a continuum damage approach based on the θ-projection method has also been used to represent tertiary creep damage and accurately predict creep rupture.

  9. Improvement of interfacial adhesion and nondestructive damage evaluation for plasma-treated PBO and Kevlar fibers/epoxy composites using micromechanical techniques and surface wettability.

    Science.gov (United States)

    Park, Joung-Man; Kim, Dae-Sik; Kim, Sung-Ryong

    2003-08-15

    Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole (PBO, Zylon) and poly(p-phenylene terephthalamide) (PPTA, Kevlar) fibers/epoxy composites were investigated using a micromechanical technique and nondestructive acoustic emission (AE). The interfacial shear strength (IFSS) and work of adhesion, Wa, of PBO or Kevlar fiber/epoxy composites increased with oxygen-plasma treatment, due to induced hydrogen and covalent bondings at their interface. Plasma-treated Kevlar fiber showed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum values. The work of adhesion and the polar term were proportional to the IFSS directly for both PBO and Kevlar fibers. The microfibril fracture pattern of two plasma-treated fibers appeared obviously. Unlike in slow cooling, in rapid cooling, case kink band and kicking in PBO fiber appeared, whereas buckling in the Kevlar fiber was observed mainly due to compressive and residual stresses. Based on the propagation of microfibril failure toward the core region, the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly compared to the untreated case. The results of nondestructive AE were consistent with microfailure modes.

  10. Improvement of interfacial adhesion and nondestructive damage evaluation for plasma-treated PBO and Kevlar fibers/epoxy composites using micromechanical techniques and surface wettability.

    Science.gov (United States)

    Park, Joung-Man; Kim, Dae-Sik; Kim, Sung-Ryong

    2003-08-15

    Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole (PBO, Zylon) and poly(p-phenylene terephthalamide) (PPTA, Kevlar) fibers/epoxy composites were investigated using a micromechanical technique and nondestructive acoustic emission (AE). The interfacial shear strength (IFSS) and work of adhesion, Wa, of PBO or Kevlar fiber/epoxy composites increased with oxygen-plasma treatment, due to induced hydrogen and covalent bondings at their interface. Plasma-treated Kevlar fiber showed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum values. The work of adhesion and the polar term were proportional to the IFSS directly for both PBO and Kevlar fibers. The microfibril fracture pattern of two plasma-treated fibers appeared obviously. Unlike in slow cooling, in rapid cooling, case kink band and kicking in PBO fiber appeared, whereas buckling in the Kevlar fiber was observed mainly due to compressive and residual stresses. Based on the propagation of microfibril failure toward the core region, the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly compared to the untreated case. The results of nondestructive AE were consistent with microfailure modes. PMID:16256662

  11. Material Induced Anisotropic Damage

    NARCIS (Netherlands)

    Niazi, M.S.; Wisselink, H.H.; Meinders, V.T.; Boogaard, van den A.H.; Hora, P.

    2012-01-01

    The anisotropy in damage can be driven by two different phenomena; anisotropic defor-mation state named Load Induced Anisotropic Damage (LIAD) and anisotropic (shape and/or distribution) second phase particles named Material Induced Anisotropic Damage (MIAD). Most anisotropic damage models are based

  12. Forty-fourth ASME International Gas Turbine and Aeroengine Technical Congress, Exposition and Users Symposium. Pt. 2. Aircraft gas turbine; 1999 nen dai 44 kai ASME kokusai gas turbine kaigi. kokuyo gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Ikeyama, M. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    1999-09-20

    This paper reports aircraft gas turbine presented at the 44th ASME International Gas Turbine and Aeroengine Technical Congress 1999. What has drawn the strongest interest was the session related to the numerical propulsion system simulation (NPSS) being developed by NASA. The simulation links into a network about 1000 computers possessed by aero-industry related companies, research institutes and universities. The network uses common models to perform analysis under parallel processing on aerodynamics, heat transfer and structures, while taking interactions into consideration. It is planned that the whole jet engines will be subjected to non-steady calculation using three-dimensional models by the year 2007. The cost will be 8% or less of that when large super computers are used. The keys to realization of a supersonic passenger aircraft are noise, exhaust gas and impulse wave, whereas there would be no market unless a method for absorbing the impulse wave is developed and the aircraft can fly over the ground. Presentations were made on a wind tunnel testing equipment for jet engines and studies on turbo-fan engines for civilian aircraft. (NEDO)

  13. 基于成熟度的航空发动机WBS技术及工作模式研究%Research on WBS Technology and Working Mode of Aeroengine Based on Maturity

    Institute of Scientific and Technical Information of China (English)

    常智勇; 金也淘; 孙惠斌; 杨海成

    2012-01-01

    Some researches on the current multi-disciplinary collaborative design process of domestic compressor of aeroengine are done, and the optimized work breakdown structure based on the concept of maturity is put forward after analyzing primary one. The concept of design maturity, the key elements of maturity model as well as work breakdown structure based on maturity are introduced, eventually testification is done on Teamcenter platform.%航空发动机工作分解结构一直是型号研制的重要依据.通过研究国内中小航空发动机压气机组件现行多学科协同设计过程,在对原来的工作分解结构进行分析后,提出基于成熟度的优化工作分解结构.使得航空发动机压气机组件的协同设计过程效率得到了提高,并在Teamcenter平台系统中进行了实例验证.

  14. Discussion on the Processing Method of Aero-Engine Rotor Integral Impeller%浅谈航空发动机整体叶轮的加工方法

    Institute of Scientific and Technical Information of China (English)

    王宏睿

    2013-01-01

      整体叶轮是航空发动机的核心部件之一,其结构复杂,叶片薄且扭曲大,叶片间隔小,特别是在高温、高压、高转速的条件下工作。通常采用钛合金、高温合金等高性能金属材料制造,这些材料极难切削,对此,浅述新型的加工工艺。%The integral impeller is the key part of the aero engine. With the increase of the engine capability, the integral impeller becomes more and more complex. The blade becomes thinner and more twisted and the tunnel is narrower. Especially in the high temperature, high pressure, high speed working condition, aero-engine rotor integral impeller was usually made of titanium alloy, high temperature alloy those metal materials was very difficult to cut. In this paper, the corresponding processing method of integral impeller was discussed.

  15. Corrosion damage evolution and residual strength of corroded aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Youhong Zhang; Guozhi Lv; Hui Wang; Bomei Si; Yueliang Cheng

    2008-01-01

    The LY12CZ aluminum alloy specimens were eurroded under the conditions of different test temperatures and exposure durations. After corrosion exposure, fatigue tests were performed. Scanning electron microscopy and optical microscope analyses on corrosion damage were carried out. The definition of surface corrosion damage ratio was provided to describe the extent of surface corrosion damage. On the basis of the measured data sets of the corrosion damage ratio, the probabilistic model of corrosion damage evolution was built. The corrosion damage decreased the fatigue life by a factor of about 1.25 to 2.38 and the prediction method of residual strength of the corroded structure was presented.

  16. Laser Damage Precursors in Fused Silica

    Energy Technology Data Exchange (ETDEWEB)

    Miller, P; Suratwala, T; Bude, J; Laurence, T A; Shen, N; Steele, W A; Feit, M; Menapace, J; Wong, L

    2009-11-11

    There is a longstanding, and largely unexplained, correlation between the laser damage susceptibility of optical components and both the surface quality of the optics, and the presence of near surface fractures in an optic. In the present work, a combination of acid leaching, acid etching, and confocal time resolved photoluminescence (CTP) microscopy has been used to study laser damage initiation at indentation sites. The combination of localized polishing and variations in indentation loads allows one to isolate and characterize the laser damage susceptibility of densified, plastically flowed and fractured fused silica. The present results suggest that: (1) laser damage initiation and growth are strongly correlated with fracture surfaces, while densified and plastically flowed material is relatively benign, and (2) fracture events result in the formation of an electronically defective rich surface layer which promotes energy transfer from the optical beam to the glass matrix.

  17. 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

  18. Development mechanism of cavity damage under urban roads and its influence on road surface subsidence%城市道路地下空洞病害发展机理及对路面塌陷的影响

    Institute of Scientific and Technical Information of China (English)

    陶连金; 袁松; 安军海

    2015-01-01

    外界因素作用易引起城市道路地下空洞破坏,甚至向上发展至地面形成地层塌陷。基于离散元软件对城市道路路基下空洞的发展破坏进行数值模拟,分析空洞规模、埋深、施工振动、空洞周围土性对空洞稳定性的影响。结果表明:道路路面沉降随着空洞埋深的减小和尺寸的增大,均出现先急剧增加后趋于平缓的过程。该曲线的拐点为道路安全性预测的关键点。当空洞与扰动土层相距3 m以内时,必须考虑施工扰动的影响。沉降值随空洞所在土层的黏聚力和摩擦角均近似呈线性变化。该研究从颗粒细观角度揭示了地下空洞发展至路面塌陷的破坏机制,为地下病害研究提供了新方法。%This paper is concerned specifically with a deeper study addressing cavity disease—cavity damage more likely to occur under urban roads due to the external factors and even cause road surface subsidence. The study involves simulating the development and damage of cavity under urban road using distinct element software and analyzing the impact of the cavity size, buried depth, the vibration during construction, the property of soil around the cavity on the stability of the cavity. The study demonstrates that, as a result of the decrease of the cavity depth and the increase of size, the road surface is subjected to the typical subsidence tending to sharply increase, followed by a flat increase, suggesting that the point of inflexion holds the key to the road safety prediction; the occurrence of a 3-m-distance between cavity and disturbed soil necessitates the consideration of the influence of vibration during construction;and sur-face has subsidence value approximate to linear variation due to the cohesive force and the friction angle of soil to which the cavity is exposed. The study offers a new insight into failure mechanism behind the underground cavity and the resulting road surface subsidence thanks to

  19. Review of probabilistic risk assessment on aero-engine airworthiness%航空发动机适航概率风险评估方法研究综述

    Institute of Scientific and Technical Information of China (English)

    丁水汀; 张弓; 蔚夺魁; 周燕佩

    2011-01-01

    In order to meet the urgent needs of developing large commercial aero-engines which satisfies the airworthiness requirments, the fundamental methodology and develop- ment progress of probabilistic risk assessment (PRA) of life limited parts in recent years were discussed. The PRA technologies, including their processes and characteristics, were described to show their compliance with the life-limited parts requirements set forth in sec- tion 33.70 of federal aviation regulations (FAR). Moreover, the core methodology and basic database structure of PRA were analyzed. It indicates that the PRA methodology should be established on the basis of combining the probabilistic fracture mechanism with accurate da- tabases.%针对我国发展满足适航性要求的大型商用航空发动机的迫切需求,分析总结了目前航空发动机寿命限制件概率风险评估的基本方法和研究进展,系统描述了满足适航规章(FAR33.70)要求的部件失效概率风险评估方法的技术流程和特点.在分析了核心方法和基础数据库架构的基础上,指出完善的概率断裂力学模型及准确的数据库支持是建立概率风险评估方法的重要基础.

  20. 航空发动机健康管理用户的诊断预测指标体系%Diagnostic and Prognostic Metrics of Aeroengine Health Management Users

    Institute of Scientific and Technical Information of China (English)

    尉询楷; 刘芳; 陈良峰; 朱纪洪; 杨立

    2012-01-01

    The need of different health management users must be met by the top design requirements of aeroengine health management. The user categories and design flow of the health management system were briefly introduced, and then the needs from the field users including logistics, flight, maintenance and fleet management were analyzed. In the perspective of diagnostics and prognostics for health management systems, the mapping relations between the different user requirements and the metrics for diagnostics and prognostics were analyzed, and the respective metrics were built. The results could help the military decision staffs make the research and development top requirements suite better for the field usage needs, also the industrial design engineers could benefit from making more satisfied research regulatory for the user requirements.%航空发动机健康管理的顶层设计必须要满足不同健康管理用户的使用要求。简要介绍了健康管理系统的用户分类和开发流程,重点分析了面向外场使用的后勤、飞行、维修、机群管理等军方健康管理用户的要求。从健康管理诊断和预测的技术实现出发,分别分析了军方不同用户的要求与诊断、预测指标之间的映射关系,建立了相应的诊断和预测指标体系。可为军方制定满足外场使用需求的研制总要求,工业部门制定贴合用户需求的研制规范提供借鉴。

  1. An analysis method for vibration fault of aero-engine intermediate bearing%航空发动机中介轴承振动故障分析方法

    Institute of Scientific and Technical Information of China (English)

    乔保栋; 葛向东; 张东明

    2015-01-01

    Because the vibration fault single of intermediate bearing is faintness, an analysis method for fault diagnosis of intermediate bearing is proposed combining the advantages of wavelet transform. First, wavelet decomposition of rolling bearing fault signal is made to get the resonance frequency bands of rolling bearing acceleration signal. Then, spectrum analysis for each separation signal is carried out, the feature fre⁃quencies of rolling bearing faults can be observed clearly. This method has been applied to the vibration sig⁃nal processing of intermediate bearing in aero-engine test, and the results show that the new method can re⁃duce noise greatly and extract fault features of intermediate bearing better.%针对中介轴承振动故障信号微弱、较难提取的问题,提出一种基于小波变换的航空发动机中介轴承故障诊断方法:首先对中介轴承故障信号进行小波分解,得到各层细节信号,并对细节信号进行重构;然后对重构信号进行频谱变换,从频谱图上清晰观察出中介轴承的故障特征频率。对真实发动机中介轴承故障信号进行的实例分析表明,本文方法具有较好的降噪能力,较频谱分析更能突出中介轴承的故障特征。

  2. CHARACTERIZATION OF DAMAGED MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P C; Dehaven, M; McClelland, M; Chidester, S; Maienschein, J L

    2006-06-23

    Thermal damage experiments were conducted on LX-04, LX-10, and LX-17 at high temperatures. Both pristine and damaged samples were characterized for their material properties. A pycnometer was used to determine sample true density and porosity. Gas permeability was measured in a newly procured system (diffusion permeameter). Burn rate was measured in the LLNL strand burner. Weight losses upon thermal exposure were insignificant. Damaged pressed parts expanded, resulting in a reduction of bulk density by up to 10%. Both gas permeabilities and burn rates of the damaged samples increased by several orders of magnitude due to higher porosity and lower density. Moduli of the damaged materials decreased significantly, an indication that the materials became weaker mechanically. Damaged materials were more sensitive to shock initiation at high temperatures. No significant sensitization was observed when the damaged samples were tested at room temperature.

  3. 内嵌CFRP板加固已损伤RC梁抗弯性能的试验研究%Experimental study on the flexural behavior of damaged reinforced concrete beams strengthened with near-surface mounted CFRP laminates

    Institute of Scientific and Technical Information of China (English)

    孙志洋; 张智梅; 刘涛

    2013-01-01

    通过对7根钢筋混凝土梁内嵌CFRP板加固的抗弯试验,探讨了CFRP板用量、损伤程度和加固方式对已损伤钢筋混凝土梁承载力、跨中挠度、破坏形态等方面的影响.试验结果表明,与未加固梁相比,已损伤的钢筋混凝土梁采用内嵌CFRP板法加固后,混凝土梁的极限承载力提高了34%~144%;CFRP板的用量对钢筋混凝土梁的抗弯性能影响较大,损伤程度对加固梁抗弯性能的影响不明显,内嵌CFRP板加固钢筋混凝土梁的抗弯性能优于外贴等量CFRP板的加固梁.基于混凝土结构加固理论,考虑开槽数量的影响,对内嵌CFRP板加固已损伤RC梁钢筋屈服前的短期刚度进行理论分析,并建立加固梁钢筋屈服前短期刚度的计算公式,其计算结果与试验实测值吻合较好.%Seven reinforced concrete beams strengthened with NSM CFRP were tested.The ultimate moment,deflection at mid span,failure mode of the test beams with the strengthening amount,damage degree and the way of strengthened were discussed.The experimental results showed that the load-bearing capacity of the beams strengthened with NSM CFRP increases from 34% to 144% comparing with the beams which are not strengthened.The flexural behavior of the concrete beams were influenced by the strengthening amount,but the damage degree just has a little influence to the flexural behavior of the concrete beams.Near-surface mounted CFRP strengthening beams has more flexural than bonded CFRP sheets strengthening beams.In consideration of the influence of the groove,the short-term rigidity were discussed for NSM CFRP laminates-strengthened damaged RC beams on the basis of the theory of concrete structure,and introduces a practical calculating method of short-term rigidity.The predicted results agree well with the measured values from the tests of the present.

  4. DNA Damage Response

    OpenAIRE

    Giglia-Mari, Giuseppina; Zotter, Angelika; Vermeulen, Wim

    2011-01-01

    Structural changes to DNA severely affect its functions, such as replication and transcription, and play a major role in age-related diseases and cancer. A complicated and entangled network of DNA damage response (DDR) mechanisms, including multiple DNA repair pathways, damage tolerance processes, and cell-cycle checkpoints safeguard genomic integrity. Like transcription and replication, DDR is a chromatin-associated process that is generally tightly controlled in time and space. As DNA damag...

  5. Laser Damage Inspection Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Salmon, J T; Brase, J M; Bliss, E S; Carrano, C J; Kegelmeyer, L M; Miller, M G; Orth, C D; Sacks, R A

    2001-02-26

    Large, high-power laser systems are often designed as reimaging multipass cavities to maximize the extraction of energy from the amplifiers. These multipass cavities often have vacuum spatial filters that suppress the growth of beam instability via B-integral effects. These spatial filters also relay images of laser damage, often nearly superimposing these images in common planes. Also, the fluence damage threshold limits the minimum size of the optics. When used as vacuum barriers in the spatial filters, these large optics present a safety hazard from the risk of implosion if the laser damage were sufficiently large. The objective of the project was to develop algorithms and methods for optical detection and characterization of laser-induced damage of optics. The system should detect small defects (about 5% of the critical size), track their growth over multiple laser shots, and characterize the defects accurately so that the optic can be replaced (at 25% of the critical size) and, hence, minimize the risk of implosion. The depth of field must be short enough to isolate the damaged vacuum barrier from other damaged optics in the beamline, and the system should also be capable of inspecting other optics in the beamline, since damage on one optic can subsequently damage subsequent optics. Laser induced damage starts as a small (<<1mm) crater and grows as material is removed on subsequent laser shots. The highly fractured rough surface of the crater scatters light from the illuminating inspection beam. This scattered light is imaged by the inspection system. Other types of defects may occur as well including inclusions in the bulk glass, tooling marks, and surface contamination. This report will discuss the detection and characterization of crater-like surface defects although the general techniques may prove useful for other types of defects. The work described here covers the development of an image processing approach and specific algorithms for defect detection

  6. Plate tectonics, damage and inheritance.

    Science.gov (United States)

    Bercovici, David; Ricard, Yanick

    2014-04-24

    The initiation of plate tectonics on Earth is a critical event in our planet's history. The time lag between the first proto-subduction (about 4 billion years ago) and global tectonics (approximately 3 billion years ago) suggests that plates and plate boundaries became widespread over a period of 1 billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates.

  7. Plate tectonics, damage and inheritance.

    Science.gov (United States)

    Bercovici, David; Ricard, Yanick

    2014-04-24

    The initiation of plate tectonics on Earth is a critical event in our planet's history. The time lag between the first proto-subduction (about 4 billion years ago) and global tectonics (approximately 3 billion years ago) suggests that plates and plate boundaries became widespread over a period of 1 billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates. PMID:24717430

  8. 低能氦离子辐照对钨和钼材料的表面损伤作用%Low-energy helium-ion irradiation on the surface damage of tungsten and molybdenum

    Institute of Scientific and Technical Information of China (English)

    李月; 范红玉; 杨铭; 张义武; 牛金海

    2015-01-01

    钨和钼材料具有高熔点、高热导率、低溅射率等优点成为国际热核实验反应堆计划中面向等离子体材料的候选材料。因此研究钨和钼材料的辐照损伤行为对于认识面向等离子体材料的辐照损伤机制具有重要意义。本文采用120 eV的 He+在873 K对钨和钼材料进行辐照实验,利用纳米压痕仪与导电模式原子力显微镜(Conductive Atomic Force Microscopy, CAFM)相结合,原位比较了钨和钼材料在辐照前后的表面形貌、表面微结构以及表层缺陷分布的变化特征。结果表明,低能He+辐照会导致钨和钼材料的近表面产生纳米量级氦泡缺陷,这些氦泡缺陷的存在使得样品表面产生绒毛或波浪状结构。纳米压痕深度分析和扫描电镜的分析结果表明,低能He+辐照会对Mo材料产生明显的刻蚀作用。本工作对于进一步认识低能氦离子辐照对面向等离子体材料的辐照损伤作用具有一定的科学参考意义。%Background: Due to their high melting point, high thermal conductivity, low sputtering yield, tungsten (W) and molybdenum (Mo) have been regarded as the potential candidates for plasma facing materials in fusion reactors.Purpose: This study aims to understand the irradiation damage behavior of W and Mo for the development of key fusion reactors materials. Methods: Polycrystalline W and Mo materials have been irradiated by 120-eV He ions with the irradiation temperature at 873 K.In situ analysis of these samples was carried out using nano-identation masked technique and non-destructive conductive atomic force microscopy (CAFM). The morphology, microscopic evolution and distribution of defects of these samples before and after irradiation are compared.Results:Analysis indicated that a large number of nanometer-sized helium bubbles were formed near the sample surface. Over-high internal pressure of nanometer-sized helium bubbles may result in forming protuberances of

  9. DNA damage response

    NARCIS (Netherlands)

    G. Giglia-Mari (Giuseppina); A. Zotter (Angelika); W. Vermeulen (Wim)

    2011-01-01

    textabstractStructural changes to DNA severely affect its functions, such as replication and transcription, and play a major role in age-related diseases and cancer. A complicated and entangled network ofDNA damage response (DDR) mechanisms, including multiple DNA repair pathways, damage tolerance p

  10. DNA damage and autophagy

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Rocha, Humberto; Garcia-Garcia, Aracely [Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583 (United States); Panayiotidis, Mihalis I. [School of Community Health Sciences, University of Nevada, Reno, NV 89557 (United States); Franco, Rodrigo, E-mail: rfrancocruz2@unl.edu [Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583 (United States)

    2011-06-03

    Both exogenous and endogenous agents are a threat to DNA integrity. Exogenous environmental agents such as ultraviolet (UV) and ionizing radiation, genotoxic chemicals and endogenous byproducts of metabolism including reactive oxygen species can cause alterations in DNA structure (DNA damage). Unrepaired DNA damage has been linked to a variety of human disorders including cancer and neurodegenerative disease. Thus, efficient mechanisms to detect DNA lesions, signal their presence and promote their repair have been evolved in cells. If DNA is effectively repaired, DNA damage response is inactivated and normal cell functioning resumes. In contrast, when DNA lesions cannot be removed, chronic DNA damage triggers specific cell responses such as cell death and senescence. Recently, DNA damage has been shown to induce autophagy, a cellular catabolic process that maintains a balance between synthesis, degradation, and recycling of cellular components. But the exact mechanisms by which DNA damage triggers autophagy are unclear. More importantly, the role of autophagy in the DNA damage response and cellular fate is unknown. In this review we analyze evidence that supports a role for autophagy as an integral part of the DNA damage response.

  11. Experimental Verification of Aero-Engine Performance Seeking Control Based on the Hybrid Model and FSQP Algorithm%基于复合模型及FSQP算法的发动机性能寻优控制试验

    Institute of Scientific and Technical Information of China (English)

    王健康; 张海波; 孙健国; 黄向华

    2012-01-01

    The application of an onboard hybrid steady-state model and feasible sequential quadratic programming (FSQP) algorithm to aero-engine performance seeking control (PSC) was studied. On the one hand, the hybrid model was es- tablished to perform PSC instead of the component-level engine model, which was favorable for the reduction of time cost dur- ing optimization process. On the other hand, FSQP algorithm was used to find the global optimal solution in PSC, which could enhance optimization precision. Finally, through both digital simulation and semi-physical simulation, the minimum fuel-con- sumption mode and the maximum thrust mode were testified. The simulation results prove that the proposed method takes the real-time advantage with the acceptable optimization effectiveness in PSC.%提出了一种在保证优化效果前提下提高发动机在线性能寻优实时性的方法,即一方面基于相似理论建立了适用于非加力状态的发动机复合稳态模型,在优化过程中替代原部件级模型以缩短优化计算时间,另一方面采用先进的可行性序列二次规划算法寻求全局最优解,以提高优化精度。最终实现了上述方案在最小油耗模式及最大推力模式下的数字仿真及半物理模拟验证,相比于传统的基于发动机部件级模型进行性能寻优控制,其优化精度相当,但优化实时性得到大幅度提高,从仿真结果可以看出上述方案的有效性及可行性。

  12. Application of Particle Swarm Optimization in Obtaining Solution of Aeroengine Component-Level Model%基于粒子群算法的发动机部件模型求解

    Institute of Scientific and Technical Information of China (English)

    钱海鹰; 杨培源; 徐松林

    2012-01-01

    The convergence of conventional solutions to nonlinear equation and component matching equations of aero- engine component model depends on the initial values. Based on the peculiarity of nonlinear equation of the model, a hybrid Particle Swarm Optimization(PSO) algorithm HPSO1 is proposed, which integrates constriction factor, passive congregation factor and adaptive inertia weight on the basis of neighbor PSO. As for component matching equations,another hybrid Particle Swarm Optimization(PSO) algorithm HPSO2 is proposed, which integrates constriction factor, passive congregation factor on the basis of basic PSO. The simulation results demonstrate that both HPSO1 and HPSO2 overcome the dependence on initial values and they are effective in obtaining solution of aeroengine component-level model.%传统求解航空发动机部件模型中的非线性方程和共同工作方程组的方法因对初值的依赖使得模型并不总能收敛。首先针对模型中的非线性方程求解的特点,在带邻域的粒子群算法的基础上,将收敛因子、被动聚集压力因子和自适应惯性权重引入算法,提出一种混合粒子群算法HPSO1。而对模型中的共同工作方程组的求解,则是在基本粒子群算法的基础上,将收敛因子和被动聚集压力因子引入基本粒子群算法,提出另一种混合粒子群算法HPS02。实验仿真表明HPS01和HPS02均青服了对初值的依赖性,因而对发动机部件模型求解是有效的。

  13. Numerical simulation on thermal radiation enviroment of a small aeroengine combustion chamber%小型航空发动机燃烧室热辐射环境数值模拟

    Institute of Scientific and Technical Information of China (English)

    刘晗; 刘跃凡

    2016-01-01

    The radiative heat transfer of high temperature gas and particles to the inner wall in the engine combus⁃tion chamber account for a large part of the total heat transfer, and it can reach 80%of the total heat transfer for lu⁃minous flame. Relevant data show that the engine combustion chamber gas and carbon black thermal radiation can achieve 2. 3 × 105 W/m2 . The reliable numerical simulations should be very important in aeroengine combustion chamber design. In this article, a small aviation combustion chamber structure was simplified, and the commercial software FLUENT was used to simulate and obtain the concentration field, temperature field, and wall heat flux un⁃der a typical condition. By analyzing the results, it shows that the radiative heat transfer lowers more than 5%of the highest temperature inside the engine combustion chamber, reducing the temperature gradient of flow field. It also has important role in the distribution of other physical quantity.%发动机燃烧室中高温气体和粒子对内壁面的辐射传热占总传热量很大一部分,对发光火焰来说能够达到总传热量的80%,有关资料表明发动机燃烧室内气体和炭黑辐射热流能达到2.3×105 W/m2,所以在先进航空发动机燃烧室的设计中需要可靠的数值仿真支持。文拟对某小型航空发动机燃烧室结构进行适当简化,并利用商业软件FLUENT数值仿真方法计算其典型工况下燃烧室内温度、组分浓度场以及壁面热流,对计算结果进行对比分析,结果表明在发动机燃烧室中考虑燃气的辐射效应使得燃烧室内最高温度降低了5%以上,使得流场的温度梯度降低,对其他各物理量的分布也具有重要的作用。

  14. 基于改进混合卡尔曼滤波器的航空发动机机载自适应模型%Aeroengine on-board adaptive model based on improved hybrid Kalman filter

    Institute of Scientific and Technical Information of China (English)

    陆军; 郭迎清; 张书刚

    2011-01-01

    提出了基于改进混合卡尔曼滤波器的航空发动机机载自适应模型方法,即以机载非线性模型的输出作为分段线性卡尔曼滤波器的稳态基准值,将性能蜕化因子作为该滤波器的增广状态量进行在线估计,并反馈给机载非线性模型使其完成在线更新.同时,根据工作模式切换机制使该模型获得有效输出.通过将该方法应用于某型涡扇发动机进行一系列仿真表明,在全飞行包线内、不同工作状态以及性能蜕化严重的情况下,该模型能够始终与实际发动机相匹配,满足实际应用需求.%A method of establishing aeroengine on-board adaptive model was proposed based on improved hybrid Kalman filter(IHKF).The output of nonlinear on-board engine model(NOBEM) was regarded as the steady-state basic model of piecewise linear Kalman filter(PWKF),while its performance deterioration factor was regarded as the augmented state vector of PWKF for on-line estimation,and fed back to NOBEM for on-line updating.In addition,the switching logic of work mode was established,which could make the IHKF work better.By applying this method to a turbofan engine,a series of simulation results show that the model can always match the actual engine in the whole flight envelope,under different engine states and severe performance deterioration,thus meeting the needs of practical applications.

  15. 基于小波包分析和支持向量机的转静碰摩部位识别%Rotor-stator rubbing positions identification of aero-engine based on wavelet packet analysis and support vector machine

    Institute of Scientific and Technical Information of China (English)

    于明月; 陈果; 李成刚; 冯国全; 王德友

    2013-01-01

    利用航空发动机转子实验器模拟不同径向碰摩部位下的碰摩故障,提出基于小波包分析的支持向量机转静碰摩部位识别方法.首先将从机匣测得的加速度信号进行小波包分解,提取其归一化能量特征,接下来将得到的归一化能量特征输入至支持向量机中,用以识别不同的碰摩部位.利用航空发动机转子实验器模拟大量不同碰摩程度和不同碰摩部位的样本,利用支持向量机进行训练和测试.结果表明小波包能量特征与支持向量机相结合可以有效地判别转静碰摩部位,且仅需1个传感器即可达到98%的识别率.%Rubbing faults of different radial rubbing positions by using the rotor experiment rig of aero-engine are simulated. An identification method based on wavelet packet analysis and support vector machine (SVM) was proposed. Firstly, the acceleration signals on the casing were collected. Secondly, the signals were decomposed by wavelet packet analysis,and the normalized energy features were extracted. Finally, the normalized energy characteristics were input into support vector machine to identify the different rubbing positions. By using an aero-engine rotor experiment rig, a large number of samples including different rubbing positions and different rubbing degrees were simulated, and the support vector machine was trained and tested by these samples. The results show that the new method combining the wavelet packet energy features and support vector machine can effectively identify the rotor-stator rubbing positions of aero-engine; in addition, only one sensor is required to reach the recognition rate of 98%.

  16. LSD and Genetic Damage

    Science.gov (United States)

    Dishotsky, Norman I.; And Others

    1971-01-01

    Reviews studies of the effects of lysergic acid diethylamide (LSD) on man and other organisms. Concludes that pure LSD injected in moderate doses does not cause chromosome or detectable genetic damage and is not a teratogen or carcinogen. (JM)

  17. Diabetes and nerve damage

    Science.gov (United States)

    Diabetic neuropathy; Diabetes - neuropathy; Diabetes - peripheral neuropathy ... In people with diabetes, the body's nerves can be damaged by decreased blood flow and a high blood sugar level. This condition is ...

  18. Bypassing damaged nervous tissue

    CERN Document Server

    Shneider, M N

    2016-01-01

    We show the principal ability of bypassing damaged demyelinated portions of nervous tissue, thereby restoring its normal function for the passage of action potentials. We carry out a theoretical analysis on the basis of the synchronization mechanism of action potential propagation along a bundle of neurons, proposed recently in [1]. And we discuss the feasibility of implement a bypass to restore damaged nervous tissue and creating an artificial neuron network.

  19. Cantilever steel post damaged by wind

    Directory of Open Access Journals (Sweden)

    Wei Sha

    2014-10-01

    Full Text Available An analysis for the cause of fracture failure of a cantilever steel sign post damaged by wind has been carried out. An unusual cause of failure has been identified, which is the subject of this paper. Microscopy and microanalysis of the fracture surface showed that the failure was due to pre-existing cracks, from the fabrication of the post. This conclusion was reached after detecting and analysing a galvanised layer on the fracture surfaces.

  20. Integrated geomechanical modelling for deep subsurface damage

    NARCIS (Netherlands)

    Wees, J.D. van; Orlic, B.; Zijl, W.; Jongerius, P.; Schreppers, G.J.; Hendriks, M.

    2001-01-01

    Government, E&P and mining industry increasingly demand fundamental insight and accurate predictions on subsurface and surface deformation and damage due to exploitation of subsurface natural resources, and subsurface storage of energy residues (e.g. CO2). At this moment deformation is difficult to

  1. The structural strength of glass: hidden damage

    NARCIS (Netherlands)

    Veer, F.A.; Rodichev, Y.M.

    2011-01-01

    We discuss “hidden damage” of glass by the rolling process, which results in heterogeneous distribution of microcracks on the edge surface of glass element, which are the fracture source deteriorating glass element strength. It is shown that removal of this damage on the edges of glass elements incr

  2. 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...

  3. Radiation damage in WC studied with MD simulations

    Energy Technology Data Exchange (ETDEWEB)

    Traeskelin, P. [Accelerator Laboratory, University of Helsinki, P.O. Box 43, FIN-00014 (Finland); Bjoerkas, C. [Accelerator Laboratory, University of Helsinki, P.O. Box 43, FIN-00014 (Finland); Juslin, N. [Accelerator Laboratory, University of Helsinki, P.O. Box 43, FIN-00014 (Finland)]. E-mail: niklas.juslin@helsinki.fi; Voertler, K. [Accelerator Laboratory, University of Helsinki, P.O. Box 43, FIN-00014 (Finland); Nordlund, K. [Accelerator Laboratory, University of Helsinki, P.O. Box 43, FIN-00014 (Finland)

    2007-04-15

    Studying radiation damage in tungsten carbide (WC) is of importance due to its applications in fusion reactors. We have used molecular dynamics to study both deuterium induced sputtering and modification of WC surfaces and collision cascades in bulk WC. For collision cascades in bulk WC we note a massive recombination and major elemental asymmetry for the damage. Studying the erosion of WC surfaces, we find that C can erode through swift chemical sputtering, while W does not sputter more easily than from pure W. The amorphization of the surface and the D-content due to the D bombardment is important for the damage production and sputtering process.

  4. Calculation of complex DNA damage induced by ions

    CERN Document Server

    Surdutovich, Eugene; Solov'yov, Andrey V

    2011-01-01

    This paper is devoted to the analysis of the complex damage of DNA irradiated by ions. The analysis and assessment of complex damage is important because cells in which it occurs are less likely to survive because the DNA repair mechanisms may not be sufficiently effective. We studied the flux of secondary electrons through the surface of nucleosomes and calculated the radial dose and the distribution of clustered damage around the ion's track. The calculated radial dose distribution is compared to simulations. The radial distribution of the complex damage is found to be different from that of the dose. Comparison with experiments may solve the question of what is more lethal for the cell, damage complexity or absorbed energy. We suggest a way to calculate the probability of cell death based on the complexity of the damage. This work is done within the framework of the phenomenon-based multiscale approach to radiation damage by ions.

  5. Cyclic damage initiation and growth in bulk metallic glass

    Science.gov (United States)

    Menzel, Brian C.

    A high-cycle stress-life fatigue study was conducted on a Zr-based bulk metallic glass to investigate damage initiation and growth mechanisms. Stress-life tests were conducted using tension-tension, compression-tension and compression-compression loadings. Distributed damage was observed to initiate rapidly from pre-existing defects as either shear bands or mixed mode surface cracks that propagated at ˜49° to the maximum tensile stress axis. On reaching a characteristic size, surface damage abruptly changed orientation and continued to grow as mode I cracks. The growth rates of these "small" surface cracks were carefully characterized and shown to be consistent with "long" crack-growth rate behavior. Fatigue life was estimated from the observed initial defect sizes and "small" crack-growth rate behavior. The resulting life predictions were found to be consistent with measured stress life data for tension-tension loading suggesting that the apparent lack of a damage initiation stage may account for the low endurance limit measured. Several surface modification techniques were explored as possible methods to reduce the number of damage initiation sites and to increase the fatigue life and the endurance limit of metallic glasses. A focused ion beam (FIB) was used to introduce well-defined distributions of initial defects to systematically elucidate damage initiation and growth processes in a separate set of specimens. High-resolution techniques were used to characterize the effect of defect size, shape and orientation on damage initiation and the early stages of damage growth. Damage initiation was found to be a strong function of defect spacing and to correspond well with region of high equivalent stress. Damage growth was also observed to correspond to directions of high equivalent stress which is highly dependent of the spacing and orientation of defects. Rapid damage initiation and mode I damage growth was observed for closely spaced defects while longer

  6. Crumpling Damaged Graphene

    CERN Document Server

    Giordanelli, I; Andrade,, J S; Gomes, M A F; Herrmann, H J

    2016-01-01

    Through molecular mechanics we find that non-covalent interactions modify the fractality of crumpled damaged graphene. Pristine graphene membranes are damaged by adding random vacancies and carbon-hydrogen bonds. Crumpled membranes exhibit a fractal dimension of $ 2.71 \\pm 0.02$ when all interactions between carbon atoms are considered, and $2.30 \\pm 0.05$ when non-covalent interactions are suppressed. The transition between these two values, obtained by switching on/off the non-covalent interactions of equilibrium configurations, is shown to be reversible and independent on thermalisation. In order to explain this transition, we propose a theoretical model that is compatible with our numerical findings. Finally, we also compare damaged graphene membranes with other crumpled structures, as for instance, polymerised membranes and paper sheets, that share similar scaling properties.

  7. Indirect identification of damage functions from damage records

    CERN Document Server

    Steinhäuser, J Micha; Kropp, Jürgen P

    2015-01-01

    In order to assess future damage caused by natural disasters, it is desirable to estimate the damage caused by single events. So called damage functions provide -- for a natural disaster of certain magnitude -- a specific damage value. However, in general, the functional form of such damage functions is unknown. We study the distributions of recorded flood damages on extended scales and deduce which damage functions lead to such distributions when the floods obey Generalized Extreme Value statistics and follow Generalized Pareto distributions. Based on the finding of broad damage distributions we investigate two possible functional forms to characterize the data. In the case of Gumbel distributed extreme events, (i) a power-law distribution density with an exponent close to 2 (Zipf's law) implies an exponential damage function; (ii) stretched exponential distribution densities imply power-law damage functions. In the case of Weibull (Frechet) distributed extreme events we find correspondingly steeper (less st...

  8. Thermal stress simulation of laser induced damage of fused silica by contamination on the surface%表面污染物诱导熔石英损伤的热力学数值模拟

    Institute of Scientific and Technical Information of China (English)

    苗心向; 袁晓东; 程晓锋; 贺少勃; 郑万国

    2011-01-01

    为了研究高功率固体激光装置内污染诱导光学元件损伤问题,基于有限元数值方法,结合污染物诱导熔石英损伤机理,给出了熔石英样片在高功率脉冲激光辐照下的温度场和应力场分布.结果表明,激光脉冲辐照过程中主要以污染物的温度升高为主,最高至2800K,而样片温升不大,仅为7K;在激光脉冲辐照后100μs的时间内,样片表面中心快速升温至2200K,而边缘处仅为700K,在较短的距离内温度变化剧烈,由此产生的热应力导致表面发生损伤;损伤区域中心表现为压应力,边缘为拉应力,最大可达30.73MPa.测试了污染物诱导样片损伤斑的微观显微形貌,实验结果和理论计算结果符合较好.%In order to study the laser-induced damage mechanism in inertial confinement fusion system, temperature and thermal stress distributions in the fused silica, heated by repetition frequency laser, were given by means of finite element methods. The simulated results indicate the temperature of the contaminations rise to 2800K during the pulse laser irradiation, but the fused silica' s temperature mainly rise from 300K to 2200K in 100μs after irradiation, and damage induced by the thermal stress occurs. The strong compressive in the damage region is about 30. 73MPa. The highest stress outside the damage region is deviatoric hoop stress. The damage morphologies were tested by means of optical microscopy. The simulated outcomes correspond to the experiment result.

  9. [Surgical therapeutic possibilities of cartilage damage].

    Science.gov (United States)

    Burkart, A C; Schoettle, P B; Imhoff, A B

    2001-09-01

    Therapy of cartilage damage is a frequent problem, especially in the young and active patient. For the treatment of a cartilage damage we have to consider the size of the defect, age and weight of the patient, meniscal tears, ligament instabilities and varus-/valgus-malalignment. Lavage, shaving and debridement are only sufficient for a short time and have no long term effect. Abrasio and drilling could be useful in eldery people. Microfracturing seems to be an effective alternative for small defects. The restoration of the cartilage surface with the use of autologous chondrocyte transplantation, osteochondral autograft transplantation and posterior condyle transfer seems to be an adequate treatment for younger patients. PMID:11572120

  10. Failure and damage analysis of advanced materials

    CERN Document Server

    Sadowski, Tomasz

    2015-01-01

    The papers in this volume present basic concepts and new developments in failure and damage analysis with focus on advanced materials such as composites, laminates, sandwiches and foams, and also new metallic materials. Starting from some mathematical foundations (limit surfaces, symmetry considerations, invariants) new experimental results and their analysis are shown. Finally, new concepts for failure prediction and analysis will be introduced and discussed as well as new methods of failure and damage prediction for advanced metallic and non-metallic materials. Based on experimental results the traditional methods will be revised.

  11. Loss and damage

    Science.gov (United States)

    Huq, Saleemul; Roberts, Erin; Fenton, Adrian

    2013-11-01

    Loss and damage is a relative newcomer to the climate change agenda. It has the potential to reinvigorate existing mitigation and adaptation efforts, but this will ultimately require leadership from developed countries and enhanced understanding of several key issues, such as limits to adaptation.

  12. Risk of nuclear damage

    International Nuclear Information System (INIS)

    Following the opening and words of welcome by Mr. Fritz Unterpertinger (unit director at the Austrian Federal Ministry for the Environment, Youth and Family; BMUJF) Mrs Helga Kromp-Kolb (professor at the Institute for Meteorology and Physics of the University of Natural Resources Science Vienna) illustrated the risks of nuclear damage in Europe by means of a nuclear risk map. She explained that even from a scientific or technical point of view the assessment of risks arising from nuclear power stations was fraught with great uncertainties. Estimates about in how far MCAs (maximum credible accident) could still be controlled by safety systems vary widely and so do assessments of the probability of a core melt. But there is wide agreement in all risk assessments conducted so far that MCAs might occur within a - from a human point of view - conceivable number of years. In this connection one has to bear in mind that the occurrence of such a major accident - whatever its probability may be - could entail immense damage and the question arises whether or not it is at all justifiable to expose the general public to such a risk. Klaus Rennings (Centre for European Economic Research, Mannheim, Germany) dealt with the economic aspects of nuclear risk assessment. He explained that there are already a number of studies available aiming to assess the risk of damage resulting from a core melt accident in economic terms. As to the probability of occurrence estimates vary widely between one incident in 3,333 and 250,000 year of reactor operation. It is assumed, however, that a nuclear accident involving a core melt in Germany would probably exceed the damage caused by the Chernobyl accident. The following speakers addressed the legal aspects of risks associated with nuclear installations. Mrs Monika Gimpel-Hinteregger (professor at the Institute for Civil Law in Graz) gave an overview on the applicable Austrian law concerning third party liability in the field of nuclear energy

  13. Density of oxidation-induced stacking faults in damaged silicon

    NARCIS (Netherlands)

    Kuper, F.G.; Hosson, J.Th.M. De; Verwey, J.F.

    1986-01-01

    A model for the relation between density and length of oxidation-induced stacking faults on damaged silicon surfaces is proposed, based on interactions of stacking faults with dislocations and neighboring stacking faults. The model agrees with experiments.

  14. A GPA diagnostic system for aeroengine applications

    Institute of Scientific and Technical Information of China (English)

    Yi-Guang Li

    2007-01-01

    In this research,a GPA(Gas Path Analysis)diagnostic system enhanced with GPA Index is described for gas path sensor and component fault diagnosis.A method of measurement correction is used in order that the measurement data obtained at un-standard ambient and operating conditions can be used for diagnostic analysis.The developed diagnostic system has been implemented into a Cranfield University gas turbine performance and diagnostic analysis software PYTHIA for gas turbine performance degradation analysis.The developed method and software have been applied to a model aero gas turbine engine to test the effectiveness of the system.The analysis shows that the developed diagnostic system can diagnose degraded sensor and components effectively using performance deviation measured at un-standard ambient and operational conditions.Theoretically,the idea of the diagnostic approach can be applied to different gas turbine engines.

  15. Experimental Replication of an Aeroengine Combustion Instability

    Science.gov (United States)

    Cohen, J. M.; Hibshman, J. R.; Proscia, W.; Rosfjord, T. J.; Wake, B. E.; McVey, J. B.; Lovett, J.; Ondas, M.; DeLaat, J.; Breisacher, K.

    2000-01-01

    Combustion instabilities in gas turbine engines are most frequently encountered during the late phases of engine development, at which point they are difficult and expensive to fix. The ability to replicate an engine-traceable combustion instability in a laboratory-scale experiment offers the opportunity to economically diagnose the problem (to determine the root cause), and to investigate solutions to the problem, such as active control. The development and validation of active combustion instability control requires that the causal dynamic processes be reproduced in experimental test facilities which can be used as a test bed for control system evaluation. This paper discusses the process through which a laboratory-scale experiment was designed to replicate an instability observed in a developmental engine. The scaling process used physically-based analyses to preserve the relevant geometric, acoustic and thermo-fluid features. The process increases the probability that results achieved in the single-nozzle experiment will be scalable to the engine.

  16. Stimulated Brillouin Scattering Damage of Large-Aperture Fused Silica Grating

    Institute of Scientific and Technical Information of China (English)

    HAN Wei; ZHENG Wan-Guo; HUANG Wan-Qing; LI Ke-Yu; WANG Fang; FENG Bin; JIA Huai-Ting; LI Fu-Quan; XIANG Yong; JING Feng

    2010-01-01

    @@ Laser induced damage experiment fs carried out on a large aperture laser facility.Severe damage is observed on a large-aperture fused silica grating which presents dense craters on the front surface and six cracks alternatively located at the front and the rear surface.The bizarre fact about the damage on the grating is that,unlike other optics,the damage craters are almost on the front surface.According to observation,damage phenomenon is due to the stimulated Brillouin scattering(SBS)effect occurring in the grating,which includes the transverse SBS,the back SBS and the zigzag SBS.

  17. Effective LiDAR Damage Detection: Comparing Two Detection Algorithms

    Institute of Scientific and Technical Information of China (English)

    BIAN Haitao; BAI Libin; WANG Xiaoyu; LIU Wangiu; CHEN Shenen; WANG Shengguo

    2011-01-01

    The health conditions of highway bridges is critical for sustained transportation operations. US federal government mandates that all bridges built with public funds are to be inspected visually every two years.There is a growing consensus that additional rapid and non-intrusive methods for bridge damage evaluation are needed. This paper explores the potential of applying ground-based laser scanners for bridge damage evaluation. LiDAR has the potential of providing high-density, full-field surface static imaging. Hence, it can generate volumetric quantification of concrete corrosion or steel erosion. By recording object surface topology, LiDAR can detect different damages on the bridge structure and differentiate damage types according to the surface flatness and smoothness. To determine the effectiveness of LiDAR damage detection, two damage detection algorithms are presented and compared using scans on actual bridge damages. The results demonstrate and validate LiDAR damage quantification, which can be a powerful tool for bridge condition evaluation.

  18. Hypertension and cerebrovascular damage.

    Science.gov (United States)

    Veglio, Franco; Paglieri, Cristina; Rabbia, Franco; Bisbocci, Daniela; Bergui, Mauro; Cerrato, Paolo

    2009-08-01

    Hypertension is the most important modifiable factor for cerebrovascular disease. Stroke and dementia are growing health problems that have considerable social and economical consequences. Hypertension causes brain lesions by several mechanisms predisposing to lacunar infarctions, leucoaraiosis, and white matter changes as well as to intracerebral haemorrhages. These parenchymal damages determine evident or silent neurological alterations that often precede the onset of cognitive decline. It is important to recognize cerebrovascular disease and, above all, to correlate typical lesions to hypertension. Antihypertensive therapy has shown clinical benefits in primary and secondary prevention of stroke. These drugs represent important instruments against cerebrovascular disease but their effects on cognition are still matter of debate. Cerebral parenchymal and functional damages have to be considered together to make medical intervention more incisive. PMID:19100549

  19. Radiation damage effects

    International Nuclear Information System (INIS)

    The summarized data suggest that both glass and crystalline waste forms may sustain substantial doses of α-decay damage and still retain their durability. Radiation effects in glasses are less pronounced and less complicated than that in single or poly-phase ceramics; thus, the latter category requires careful research and consideration. Perhaps the most important conclusion is that short-term actinide doping experiments in crystalline phases provide a realistic simulation of long-term effects based on the comparison of observed radiation effects in Pu-doped zircon and naturally damaged zircon (there is a 107 difference in dose rate). Deviations from the similarity in effect (e.g., saturation dose) may be attributed to low-temperature, long-term annealing effects

  20. Compensation for nuclear damage

    International Nuclear Information System (INIS)

    To secure fair and efficient compensation for damage likely to be caused by the utilisation of nuclear energy, a special civil liability regime was set up by several international conventions. Three of these conventions are in force and Spain is a Contracting Party to all three. The principles established in the first instance at European level by the Paris Convention (absolute and exclusive liability of the nuclear operator, limitation of such liability, compulsory insurance...) are intended to guarantee that possible victims of a nuclear incident will obtain compensation for damage suffered. The Brussels Convention Supplementary to the Paris Convention provides for official funds to compensate victims through intervention by the Contracting Parties. Each Contracting Party should implement these Conventions at national level by appropriate legislation, which is what Spain did with its Act on Nuclear Energy of 29th April 1964, as supplemented in 1967 by the Regulations on Cover for Nuclear Hazards. (N.E.A.)

  1. Restoring Damaged Aquatic Ecosystems

    OpenAIRE

    Cairns, John

    2006-01-01

    Aquatic ecosystems must play a major role to ensure that water, which is both essential and scarce, is always available for both present and future generations. This has become even more urgent in light of the ongoing increase in total world population and predicted changes in the world climate. Since aquatic ecosystems have been damaged at a rate far in excess of both natural restoration and anthropogenic restoration, it is essential that both restorative processes be accelerated. However, e...

  2. Tornado damage risk assessment

    International Nuclear Information System (INIS)

    Several proposed models were evaluated for predicting tornado wind speed probabilities at nuclear plant sites as part of a program to develop statistical data on tornadoes needed for probability-based load combination analysis. A unified model was developed which synthesized the desired aspects of tornado occurrence and damage potential. The sensitivity of wind speed probability estimates to various tornado modeling assumptions are examined, and the probability distributions of tornado wind speed that are needed for load combination studies are presented

  3. A two-scale damage model with material length

    Science.gov (United States)

    Dascalu, Cristian

    2009-09-01

    The Note presents the formulation of a class of two-scale damage models involving a micro-structural length. A homogenization method based on asymptotic developments is employed to deduce the macroscopic damage equations. The damage model completely results from energy-based micro-crack propagation laws, without supplementary phenomenological assumptions. We show that the resulting two-scale model has the property of capturing micro-structural lengths. When damage evolves, the micro-structural length is given by the ratio of the surface density of energy dissipated during the micro-crack growth and the macroscopic damage energy release rate per unit volume of the material. The use of fracture criteria based on resistance curves or power laws for sub-critical growth of micro-cracks leads to quasi-brittle and, respectively, time-dependent damage models. To cite this article: C. Dascalu, C. R. Mecanique 337 (2009).

  4. Cavitation damage prediction for the JSNS mercury target vessel

    Science.gov (United States)

    Naoe, Takashi; Kogawa, Hiroyuki; Wakui, Takashi; Haga, Katsuhiro; Teshigawara, Makoto; Kinoshita, Hidetaka; Takada, Hiroshi; Futakawa, Masatoshi

    2016-01-01

    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.

  5. 冻融后表层混凝土的孔结构劣化与损伤特性研究%A Study on Deterioation of Pore Structure and Damage Property of Surface Concrete Caused by Freeze-Thaw Action

    Institute of Scientific and Technical Information of China (English)

    朱方之; 赵铁军; 张鹏; 张连水

    2011-01-01

    采用压汞试验和中子透射成像技术研究了冻融后表层混凝土孔结构劣化及损伤特性.结果表明:冻融循环作用改变混凝土的微观孔结构的特征,临界孔径成倍数增加,毛细孔等有害孔数量明显增多;表层混凝土在冻融循环作用下孔结构劣化和强度降低更为剧烈,由表及里存在一个损伤梯度.采用表面涂覆或表面浸渍等技术提高表层混凝土抗冻性对延长结构的使用寿命具有重要意义.%The micro-porous structure and damage properties of the surface concrete in freeze-thaw environment are studied by means of mercury intrusion test and neutron radiography technique. Results show that the pore structure characteristics of concrete are deteriorated, the critical aperture doubly enlarged and the number of harmful hole significantly increased after freeze-thaw cycles. The pore structure and strength of surface concrete degradation are more serious than the internal concrete, which has a damage gradient from external to internal. So it is very important to improve the frost resistance of surface concrete for the service life of structure by surface coating or dipping.

  6. The cavitation erosion damage process of dynamically loaded journal bearings

    Institute of Scientific and Technical Information of China (English)

    MA Yan-yan; CHENG Xian-hua

    2006-01-01

    The cavitation damage model was built using finite element analysis software MSC.Marc.This paper attempted to numerically analyze the action process based on damage mechanics when a jet created by bubble collapse acted on the bearing surface in the process of cavitation erosion.The numerical results show that the values of equivalent plastic strain and void volume fraction increase with time.The values of damage scalar are higher on the bearing surface and subsurface,and decrease when it approaches the interface of overlay and nickel layer.The strain history and damage evolvement of beating material acted on by jet impact load can be calculated efficiently using the proposed method,which develops a new method of analyzing cavitation erosion failure of thebearing surface.

  7. Damage Modelling For Composite Structures

    OpenAIRE

    Lee, Hao

    2015-01-01

    Modelling damage in composite materials has played an important role in designing composite structures. Although numerical models for the progressive damage in laminated composites (e.g. transverse cracking, delamination and fibre breakage) have been developed in the literature, there is still a need for further improvement. This thesis aimed at developing damage models suitable for predicting intra-laminar and inter-laminar damage behaviour in fibre-reinforced composite materials. Several ap...

  8. Radiation damage in semiconductor detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kraner, H.W.

    1981-12-01

    A survey is presented of the important damage-producing interactions in semiconductor detectors and estimates of defect numbers are made for MeV protons, neutrons and electrons. Damage effects of fast neutrons in germanium gamma ray spectrometers are given in some detail. General effects in silicon detectors are discussed and damage constants and their relationship to leakage current is introduced.

  9. Tokamak ARC damage

    International Nuclear Information System (INIS)

    Tokamak fusion reactors will have large plasma currents of approximately 10 MA with hundreds of megajoules stored in the magnetic fields. When a major plasma instability occurs, the disruption of the plasma current induces voltage in the adjacent conducting structures, giving rise to large transient currents. The induced voltages may be sufficiently high to cause arcing across sector gaps or from one protruding component to another. This report reviews a tokamak arcing scenario and provides guidelines for designing tokamaks to minimize the possibility of arc damage

  10. Contextualizing aquired brain damage

    DEFF Research Database (Denmark)

    Nielsen, Charlotte Marie Bisgaard

    Contextualizing aquired brain damage Traditional approaches study ’communicational problems’ often in a discourse of disabledness or deficitness. With an ontology of communcation as something unique and a presupposed uniqueness of each one of us, how could an integrational approach (Integrational...... for people with aquired brain injuries will be presented and comparatively discussed in a traditional versus an integrational perspective. Preliminary results and considerations on ”methods” and ”participation” from this study will be presented along with an overview of the project's empirical data....

  11. Fatigue Damage in Wood

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Bo Uhre; Hoffmeyer, Preben;

    1996-01-01

    An investigation of fatigue failure in wood subjected to load cycles in compression parallel to grain is presented. Fatigue failure is found to depend both on the total time under load and on the number of cycles.Recent accelerated fatigue research on wood is reviewed, and a discrepancy between...... to 10 Hz are used. The number of cycles to failure is found to be a poor measure of the fatigue performance of wood. Creep, maximum strain, stiffness and work are monitored throughout the fatigue tests. Accumulated creep is suggested identified with damage and a correlation between stiffness reduction...

  12. Radiation damage in graphite

    CERN Document Server

    Simmons, John Harry Walrond

    1965-01-01

    Nuclear Energy, Volume 102: Radiation Damage in Graphite provides a general account of the effects of irradiation on graphite. This book presents valuable work on the structure of the defects produced in graphite crystals by irradiation. Organized into eight chapters, this volume begins with an overview of the description of the methods of manufacturing graphite and of its physical properties. This text then presents details of the method of setting up a scale of irradiation dose. Other chapters consider the effect of irradiation at a given temperature on a physical property of graphite. This

  13. A finite element modeling method of aero-engine rotor without physical prototype%一种无样机的航空发动机转子有限元建模方法

    Institute of Scientific and Technical Information of China (English)

    边杰; 梅庆; 臧朝平; 杨海

    2015-01-01

    established. As the frequency error of the reference model and tested model is within 3%, the reference model can be used to update the simplified model. Finally, a correlation was analyzed and frequency response functions between the tested model and updated simplified model were com-pared. The frequency differences of them are in 2%, and matching values of modal assurance criteri-on are higher than 81%, which verified the correctness and effectiveness of the updated simplified model updated by the reference model. When this method is used to establish finite element model of a real aero-engine without physical prototype, the calculation accuracy can be improved and the a-mount of calculation can be reduced, also the period of research and development can be shortened.

  14. Excavation damaged zone

    Energy Technology Data Exchange (ETDEWEB)

    Popp, T.; Salzer, K.; Minkley, W. [Institut fur Gebirgsmechanik GmbH, Leipzig (Germany); Gibert, D.; Nicollin, F.; Kergosien, B. [Rennes-1 Univ., GdR FORPRO (CNRS/ANDRA GdR 788) and Geosciences Rennes (CNRS/UR1 UMR 6118) (France); Bossart, P. [Federal Office for Topography, Wabern (Switzerland); Nussbaum, C. [Institut Geotechnique SA, St-Ursanne (Switzerland); Robinet, J.C.; Nguyen, M.T. [EGC Euro-Geomat-Consulting, 45 - Orleans (France); Barnichon, J.D.; Plas, F. [ANDRA - Agence Nationale pour la Gestion des Dechets Radioactifs, 92 - Chatenay Malabry (France); Ghorbani, A.; Cosenza, P.; Florsch, N. [Pierre et Marie Curie Univ., UMR 7619 Sisyphe, 75 - Paris (France); Revil, A.; Jougnot, D. [Aix-Marseille-2, UMR 6635, CNRS-CEREGE, 13 (France); Schmutz, M. [EGID, M. de Montaigne Univ., 33 - Pessac (France); Contrucci, I.; Klein, E. [Institut National de l' Environnement Industriel et des Risques (INERIS), Ecole des Mines de Nancy, 54 - Nancy (France); Cabrera, J.; Ben-Slimane, K.; Rejeb, A.; Matray, J.M.; Savoye, S. [Institut de Radioprotection et de Surete Nucleaire (IRSN), 92 - Fontenay-aux-Roses (France); Maiolino, S. [Ecole Polytechnique, Lab. de Mecanique des Solides, UMR 7649, LMS, 91 - Palaiseau (France); CETE de Lyon/LRPC de Lyon/Meca Roches/ ERA, 69 - Bron (France); Yong, S.; Loew, S.; Fidelibus, C.; Lemy, F. [Engineering Geology, ETH Zurich, Zurich (Switzerland); Frank, E. [Swiss Federal Nuclear Safety Inspectorate (HSK), Villigen (Switzerland); Chun-Liang, Zhang; Tilmann, Rothfuchs [Gesellschaft fur Anlagen- und Reaktorsicherheit (GRS) mbH, Braunschweig (Germany)

    2007-07-01

    This session gathers 10 articles (posters) dealing with: the influence of bedding planes to EDZ evolution and the coupled HM properties of Opalinus Clay; the electrical tomography monitoring of the EDZ during the excavation of the gallery 04 in the Mont Terri rock laboratory; the seismic endoscopy and tomography of the EDZ of the gallery 04 in the Mont Terri rock laboratory; a elastoplastic damage model for saturated and unsaturated stiffness clays: description and application to the modelling of EDZ around drifts in Callovo-Oxfordian argillites; the non-invasive monitoring of water content and microcracks in argillites using spectral induced polarization; EDZ investigations by ultrasonic borehole logging in drifts of different ages excavated in argillaceous formations of the Tournemire experimental station (Aveyron, France); the excavation damaged zones in the argillaceous Tournemire site: characterisation and failure mechanisms; the hardening-based degradation factor: influence of mean stress and stiffness; the disturbance in the EDZ in the Opalinus clay at Mont Terri; and the experimental study on self-sealing capacity of clay rocks.

  15. Guide waves-based multi-damage identification using a local probability-based diagnostic imaging method

    Science.gov (United States)

    Gao, Dongyue; Wu, Zhanjun; Yang, Lei; Zheng, Yuebin

    2016-04-01

    Multi-damage identification is an important and challenging task in the research of guide waves-based structural health monitoring. In this paper, a multi-damage identification method is presented using a guide waves-based local probability-based diagnostic imaging (PDI) method. The method includes a path damage judgment stage, a multi-damage judgment stage and a multi-damage imaging stage. First, damage imaging was performed by partition. The damage imaging regions are divided into beside damage signal paths. The difference in guide waves propagation characteristics between cross and beside damage paths is proposed by theoretical analysis of the guide wave signal feature. The time-of-flight difference of paths is used as a factor to distinguish between cross and beside damage paths. Then, a global PDI method (damage identification using all paths in the sensor network) is performed using the beside damage path network. If the global PDI damage zone crosses the beside damage path, it means that the discrete multi-damage model (such as a group of holes or cracks) has been misjudged as a continuum single-damage model (such as a single hole or crack) by the global PDI method. Subsequently, damage imaging regions are separated by beside damage path and local PDI (damage identification using paths in the damage imaging regions) is performed in each damage imaging region. Finally, multi-damage identification results are obtained by superimposing the local damage imaging results and the marked cross damage paths. The method is employed to inspect the multi-damage in an aluminum plate with a surface-mounted piezoelectric ceramic sensors network. The results show that the guide waves-based multi-damage identification method is capable of visualizing the presence, quantity and location of structural damage.

  16. 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)

  17. Laboratory Evaluation of Aggregate Polishing as a function of Load and Velocity : Application to the Prediction of Damages on Skid Resistance of Pavement Surface due to Trucks and Passenger Cars

    OpenAIRE

    Kane, Malal; ZHAO, Dan; De Larrard, François; Do, Minh Tan

    2012-01-01

    Skid resistance of road surfaces depends mostly on pavement texture. This texture is usually divided to two components:microtexture and macrotexture. Microtexture refers to the smallscale texture of the road aggregate component while macrotexture refers to the large-scale texture of the road as a whole due to the aggregate particle arrangement. Both components contribute to the generation of friction between tyre and road. However, due to traffic, the firstcited component is continuously poli...

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

    Institute of Scientific and Technical Information of China (English)

    HUANG Wan-Qing; ZHANG Xiao-Min; HAN Wei; WANG Fang; XIANG Yong; LI Fu-Quan; FENG Bin; JING Feng; WEI Xiao-Feng; ZHENG Wan-Guo

    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.

  19. Damage scenarios and an onboard support system for damaged ships

    Directory of Open Access Journals (Sweden)

    Choi Jin

    2014-06-01

    Full Text Available Although a safety assessment of damaged ships, which considers environmental conditions such as waves and wind, is important in both the design and operation phases of ships, in Korea, rules or guidelines to conduct such assessments are not yet developed. However, NATO and European maritime societies have developed guidelines for a safety assessment. Therefore, it is required to develop rules or guidelines for safety assessments such as the Naval Ship Code (NSC of NATO. Before the safety assessment of a damaged ship can be performed, the available damage scenarios must be developed and the safety assessment criteria must be established. In this paper, the parameters related to damage by accidents are identified and categorized when developing damage scenarios. The need for damage safety assessment criteria is discussed, and an example is presented. In addition, a concept and specifications for the DB-based supporting system, which is used in the operation phases, are proposed.

  20. Progressive damage state evolution and quantification in composites

    Science.gov (United States)

    Patra, Subir; Banerjee, Sourav

    2016-04-01

    Precursor damage state quantification can be helpful for safety and operation of aircraft and defense equipment's. Damage develops in the composite material in the form of matrix cracking, fiber breakages and deboning, etc. However, detection and quantification of the damage modes at their very early stage is not possible unless modifications of the existing indispensable techniques are conceived, particularly for the quantification of multiscale damages at their early stage. Here, we present a novel nonlocal mechanics based damage detection technique for precursor damage state quantification. Micro-continuum physics is used by modifying the Christoffel equation. American society of testing and materials (ASTM) standard woven carbon fiber (CFRP) specimens were tested under Tension-Tension fatigue loading at the interval of 25,000 cycles until 500,000 cycles. Scanning Acoustic Microcopy (SAM) and Optical Microscopy (OM) were used to examine the damage development at the same interval. Surface Acoustic Wave (SAW) velocity profile on a representative volume element (RVE) of the specimen were calculated at the regular interval of 50,000 cycles. Nonlocal parameters were calculated form the micromorphic wave dispersion curve at a particular frequency of 50 MHz. We used a previously formulated parameter called "Damage entropy" which is a measure of the damage growth in the material calculated with the loading cycle. Damage entropy (DE) was calculated at every pixel on the RVE and the mean of DE was plotted at the loading interval of 25,000 cycle. Growth of DE with fatigue loading cycles was observed. Optical Imaging also performed at the interval of 25,000 cycles to investigate the development of damage inside the materials. We also calculated the mean value of the Surface Acoustic Wave (SAW) velocity and plotted with fatigue cycle which is correlated further with Damage Entropy (DE). Statistical analysis of the Surface Acoustic Wave profile (SAW) obtained at different

  1. Radiation Damage Workshop

    Science.gov (United States)

    Stella, P. M.

    1984-01-01

    The availability of data regarding the radiation behavior of GaAs and silicon solar cells is discussed as well as efforts to provide sufficient information. Other materials are considered too immature for reasonable radiation evaluation. The lack of concern over the possible catastrophic radiation degradation in cascade cells is a potentially serious problem. Lithium counterdoping shows potential for removing damage in irradiated P-type material, although initial efficiencies are not comparable to current state of the art. The possibility of refining the lithium doping method to maintain high initial efficiencies and combining it with radiation tolerant structures such as thin BSF cells or vertical junction cells could provide a substantial improvement in EOL efficiencies. Laser annealing of junctions, either those formed ion implantation or diffusion, may not only improve initial cell performance but might also reduce the radiation degradation rate.

  2. Dynamic damage in carbon-fibre composites.

    Science.gov (United States)

    Bourne, N K; Parry, S; Townsend, D; Withers, P J; Soutis, C; Frias, C

    2016-07-13

    The Taylor test is used to determine damage evolution in carbon-fibre composites across a range of strain rates. The hierarchy of damage across the scales is key in determining the suite of operating mechanisms and high-speed diagnostics are used to determine states during dynamic loading. Experiments record the test response as a function of the orientation of the cylinder cut from the engineered multi-ply composite with high-speed photography and post-mortem target examination. The ensuing damage occurs during the shock compression phase but three other tensile loading modes operate during the test and these are explored. Experiment has shown that ply orientations respond to two components of release; longitudinal and radial as well as the hoop stresses generated in inelastic flow at the impact surface. The test is a discriminant not only of damage thresholds but of local failure modes and their kinetics. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.

  3. Dynamic damage in carbon-fibre composites.

    Science.gov (United States)

    Bourne, N K; Parry, S; Townsend, D; Withers, P J; Soutis, C; Frias, C

    2016-07-13

    The Taylor test is used to determine damage evolution in carbon-fibre composites across a range of strain rates. The hierarchy of damage across the scales is key in determining the suite of operating mechanisms and high-speed diagnostics are used to determine states during dynamic loading. Experiments record the test response as a function of the orientation of the cylinder cut from the engineered multi-ply composite with high-speed photography and post-mortem target examination. The ensuing damage occurs during the shock compression phase but three other tensile loading modes operate during the test and these are explored. Experiment has shown that ply orientations respond to two components of release; longitudinal and radial as well as the hoop stresses generated in inelastic flow at the impact surface. The test is a discriminant not only of damage thresholds but of local failure modes and their kinetics. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242311

  4. High laser damage threshold coatings and damage testing technology

    Institute of Scientific and Technical Information of China (English)

    MA Ping; HU Jian-ping; CHEN Song-lin; TANG Ming; WANG Zhen; LI Wei; XU Qiao

    2005-01-01

    The laser-induced damage threshold(LIDT) of optical coating is a limited factor for development of a high peak power laser. The automatic damage testing facility was built to determine the LIDT of optics at 1 064 nm and 355 nm.. The cleanning and processing procedure of the substrate and coating technique were improved, and the damage resistance of high-reflective coating at 1 064 nm was increased.

  5. Multivariate pluvial flood damage models

    Energy Technology Data Exchange (ETDEWEB)

    Van Ootegem, Luc [HIVA — University of Louvain (Belgium); SHERPPA — Ghent University (Belgium); Verhofstadt, Elsy [SHERPPA — Ghent University (Belgium); Van Herck, Kristine; Creten, Tom [HIVA — University of Louvain (Belgium)

    2015-09-15

    Depth–damage-functions, relating the monetary flood damage to the depth of the inundation, are commonly used in the case of fluvial floods (floods caused by a river overflowing). We construct four multivariate damage models for pluvial floods (caused by extreme rainfall) by differentiating on the one hand between ground floor floods and basement floods and on the other hand between damage to residential buildings and damage to housing contents. We do not only take into account the effect of flood-depth on damage, but also incorporate the effects of non-hazard indicators (building characteristics, behavioural indicators and socio-economic variables). By using a Tobit-estimation technique on identified victims of pluvial floods in Flanders (Belgium), we take into account the effect of cases of reported zero damage. Our results show that the flood depth is an important predictor of damage, but with a diverging impact between ground floor floods and basement floods. Also non-hazard indicators are important. For example being aware of the risk just before the water enters the building reduces content damage considerably, underlining the importance of warning systems and policy in this case of pluvial floods. - Highlights: • Prediction of damage of pluvial floods using also non-hazard information • We include ‘no damage cases’ using a Tobit model. • The damage of flood depth is stronger for ground floor than for basement floods. • Non-hazard indicators are especially important for content damage. • Potential gain of policies that increase awareness of flood risks.

  6. Damage tolerance assessment of composite sandwich panels with localised damage

    OpenAIRE

    Zenkert, Dan; Shipsha, Andrey; Bull, Peter; Hayman, Brian

    2005-01-01

    The work described herein is part of a larger context in which the effect of damage in sandwich composite structures for marine applications has been investigated. The overall aim of this effort has been twofold: to develop and verify existing damage assessment models to be used to assess the effect of damage on marine sandwich structures, and to develop a damage assessment scheme to be used by shipyards, ship owners and navies. More specifically, this paper presents a sub-set of this overall...

  7. Damage free Ar ion plasma surface treatment on In{sub 0.53}Ga{sub 0.47}As-on-silicon metal-oxide-semiconductor device

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Donghyi; Shin, Seung Heon; Ahn, Jaehyun; Sonde, Sushant; Banerjee, Sanjay K. [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Road, Austin, Texas 78758 (United States); Kwon, Hyuk-Min [SK Hynix, Icheon, 2091, Gyeongchung-daero, Bubal-eub, Icheon-si, Gyeonggi-do 136-1 (Korea, Republic of); Orzali, Tommaso; Kim, Tae-Woo, E-mail: twkim78@gmail.com [SEMATECH Inc., 257 Fuller Rd #2200, Albany, New York 12203 (United States); Kim, Dae-Hyun [Kyungpook National University, 80, Daehak-ro, Buk-gu, Daegu 702-701 (Korea, Republic of)

    2015-11-02

    In this paper, we investigated the effect of in-situ Ar ion plasma surface pre-treatment in order to improve the interface properties of In{sub 0.53}Ga{sub 0.47}As for high-κ top-gate oxide deposition. X-ray photoelectron spectroscopy (XPS) and metal-oxide-semiconductor capacitors (MOSCAPs) demonstrate that Ar ion treatment removes the native oxide on In{sub 0.53}Ga{sub 0.47}As. The XPS spectra of Ar treated In{sub 0.53}Ga{sub 0.47}As show a decrease in the AsO{sub x} and GaO{sub x} signal intensities, and the MOSCAPs show higher accumulation capacitance (C{sub acc}), along with reduced frequency dispersion. In addition, Ar treatment is found to suppress the interface trap density (D{sub it}), which thereby led to a reduction in the threshold voltage (V{sub th}) degradation during constant voltage stress and relaxation. These results outline the potential of surface treatment for III-V channel metal-oxide-semiconductor devices and application to non-planar device process.

  8. Damage in Fiber Bundle Models

    OpenAIRE

    Kun, Ferenc; Zapperi, Stefano; Herrmann, Hans J.

    1999-01-01

    We introduce a continuous damage fiber bundle model that gives rise to macroscopic plasticity and compare its behavior with that of dry fiber bundles. Several interesting constitutive behaviors are found in this model depending on the value of the damage parameter and on the form of the disorder distribution. In addition, we compare the behavior of global load transfer models with local load transfer models and study in detail the damage evolution before failure. We emphasize the analogies be...

  9. 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...... of the first structural blade mode. However, due to the nature of the proposed method, it is also found that the accuracy of the damage assessment highly depends on the number of employed measurement points....

  10. 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.

  11. Damage and structural defects in the surface lager of pure molybdenum induced by high-current pulsed electron beam%强流脉冲电子束辐照诱发纯钼表面的损伤效应及结构缺陷

    Institute of Scientific and Technical Information of China (English)

    季乐; 杨盛志; 蔡杰; 李艳; 王晓彤; 张在强; 侯秀丽; 关庆丰

    2013-01-01

    利用强流脉冲电子束(HCPEB)装置对纯钼表面进行辐照处理,并利用X射线衍射仪,扫描电子显微镜(SEM)、透射电子显微镜(TEM)详细分析了辐照表面的微观结构和损伤效应.1次HCPEB辐照后,纯钼表层积聚了极大的残余应力,多次辐照后表面未融化区域出现大量绝热剪切带,且局部区域发生开裂.微观结构分析显示,辐照后材料表面形成发散状的位错组态和大量空位簇缺陷;绝热剪切带内部是尺寸为1µm左右等轴状的再结晶晶粒.剪切带造成的材料表面局部软化以及间隙原子偏聚于晶界是材料发生开裂的主要原因.另外,表面熔化区域可形成尺寸为20 nm左右的纳米晶.%High-current pulsed electron beam (HCPEB) technique was applied to induce the surface irradiation of pure molybdenum. Mi-crostructures and damaging effect of the irradiated surface were investigated in detail by X-ray diffraction, scanning electron mi-croscopy (SEM) and transmission electron microscopy (TEM). After 1 pulse of HCPEB irradiation, a high level of residual stress is amassed in the irradiated surface layer, while after several pulses of irradiation, a large number of adiabatic shear bands are formed on the unmelted regions of the surface, and local cracking occurs in these regions. Microstructure observations show that scattered dislocations and large amounts of vacancy clusters are formed on the irradiated surface. The adiabatic shear bands are composed of fine recrystallized grains with an average size about 1 µm. The partial softening of the irradiated surface induced by adiabatic shear bands, and the segregation of interstitial atoms in grain boundaries are primarily responsible for the surface cracking of the material. Further, nanocrystallines (20 nm) are also formed in some melted regions of the surface.

  12. Damage control productivity : an input damage abatement approach

    NARCIS (Netherlands)

    Oude Lansink, A.G.J.M.; Carpentier, A.

    2001-01-01

    This paper compares the value of the marginal product of three different pesticides from different specifications of the production function. The specifications are the output damage abatement specification proposed by Lichtenberg and Zilberman, a general input damage abatement specification and a t

  13. Plasma Soluble (Prorenin Receptor Reflects Renal Damage.

    Directory of Open Access Journals (Sweden)

    Naro Ohashi

    Full Text Available (Prorenin receptor [(PRR], a specific receptor for renin and prorenin, was identified as a member of the renin-angiotensin system (RAS. (PRR is cleaved by furin, and soluble (PRR [s(PRR] is secreted into the extracellular space. Previous reports have indicated that plasma s(PRR levels show a significant positive relationship with urinary protein levels, which represent renal damage. However, it is not fully known whether plasma s(PRR reflects renal damage.We recruited 25 patients who were admitted to our hospital to undergo heminephrectomy. Plasma s(PRR levels were examined from blood samples drawn before nephrectomy. The extent of renal damage was evaluated by the levels of tubulointerstitial fibrosis. Immunohistochemical analysis of intrarenal (PRR and cell surface markers (cluster of differentiation [CD]3, CD19, and CD68 was performed on samples taken from the removed kidney. Moreover, double staining of (PRR and cell surface markers was also performed.There were significant positive relationships between plasma s(PRR and tubulointerstitial fibrosis in all the patients and those not receiving RAS blocker therapy. Significant positive relationships were found between plasma s(PRR levels and the extent of tubulointerstitial fibrosis after adjustment for age, sex, body weight, blood pressure, and plasma angiotensin II, in all the patients and those not receiving RAS blockers. Moreover, (PRR expression was elevated in infiltrated mononuclear cells but not connecting tubules or collecting ducts and vessels. Infiltrated cells positive for (PRR consisted of CD3 and CD68 but not CD19.These data suggest that plasma s(PRR levels may reflect (PRR expression levels in infiltrated mononuclear cells, which can be a surrogate marker of renal damage.

  14. Shock Initiation of Damaged Explosives

    Energy Technology Data Exchange (ETDEWEB)

    Chidester, S K; Vandersall, K S; Tarver, C M

    2009-10-22

    Explosive and propellant charges are subjected to various mechanical and thermal insults that can increase their sensitivity over the course of their lifetimes. To quantify this effect, shock initiation experiments were performed on mechanically and thermally damaged LX-04 (85% HMX, 15% Viton by weight) and PBX 9502 (95% TATB, 5% Kel-F by weight) to obtain in-situ manganin pressure gauge data and run distances to detonation at various shock pressures. We report the behavior of the HMX-based explosive LX-04 that was damaged mechanically by applying a compressive load of 600 psi for 20,000 cycles, thus creating many small narrow cracks, or by cutting wedge shaped parts that were then loosely reassembled, thus creating a few large cracks. The thermally damaged LX-04 charges were heated to 190 C for long enough for the beta to delta solid - solid phase transition to occur, and then cooled to ambient temperature. Mechanically damaged LX-04 exhibited only slightly increased shock sensitivity, while thermally damaged LX-04 was much more shock sensitive. Similarly, the insensitive explosive PBX 9502 was mechanically damaged using the same two techniques. Since PBX 9502 does not undergo a solid - solid phase transition but does undergo irreversible or 'rachet' growth when thermally cycled, thermal damage to PBX 9502 was induced by this procedure. As for LX-04, the thermally damaged PBX 9502 demonstrated a greater shock sensitivity than mechanically damaged PBX 9502. The Ignition and Growth reactive flow model calculated the increased sensitivities by igniting more damaged LX-04 and PBX 9502 near the shock front based on the measured densities (porosities) of the damaged charges.

  15. A study of cyclic fatigue, damage initiation, damage propagation, and fracture of welded titanium alloy plate

    International Nuclear Information System (INIS)

    In this paper, the influence of test specimen orientation and microstructure on cyclic stress-amplitude controlled fatigue response, damage initiation, damage propagation and fracture behavior of samples taken from a welded plate of titanium alloy is presented and discussed. Test specimens from the chosen alloy were prepared from an as-welded plate of the material with the stress axis both parallel (longitudinal) and perpendicular (transverse) to the deformed (rolling) direction of the plate. The test specimens were cyclically deformed at different values of maximum stress at a constant load ratio of 0.1, and the resultant cycles-to-failure was recorded. The fracture surfaces of the deformed and failed test specimens were examined in a scanning electron microscope to establish the macroscopic fracture mode, the intrinsic features on the fatigue fracture surface and the role of applied stress-microstructural feature interactions in establishing the microscopic mechanisms governing failure.

  16. Study on Laser-Assisted Rejuvenation of Inter-Granular Corrosion Damaged Type 304 Stainless Steel

    Science.gov (United States)

    Gupta, R. K.; Bhardwaj, V. K.; Agrawal, D. K.; Kumar, Manoj; Upadhyay, B. N.; Sankar, P. Ram; Ganesh, P.; Kaul, R.; Oak, S. M.; Kukreja, L. M.

    2015-09-01

    The paper evaluates laser surface melting treatment for rejuvenation of inter-granular corrosion damaged type 304 stainless steel. Surface melting of inter-granular corrosion damaged specimens with CW CO2 and pulsed Nd:YAG lasers was quite effective in sealing surface damage. However, inter-granular corrosion susceptibility of laser-rejuvenated surface was strongly influenced by associated thermal exposure. With respect to CW CO2 laser, pulsed Nd:YAG laser-rejuvenated surface demonstrated significantly suppressed micro-structural damage and IGC-susceptibility. Compact pulsed Nd:YAG laser, with flexible beam transportation, presents an effective tool for in-situ rejuvenation of inter-granular corrosion damaged in-service stainless steel components operating in susceptible environments.

  17. Chelyabinsk meteoroid entry and airburst damage

    Science.gov (United States)

    Popova, Olga; Emel'yanenko, Vacheslav; Kartashova, Anna; Rybnov, Yurij; Shuvalov, Valery; Jenniskens, Peter; Kharlamov, Vladimir

    The Chelyabinsk airburst of 15 February 2013, was exceptional because of the large kinetic energy of the impacting body and the airburst that was generated, which created significant damage on the ground and numerous injuries in a populated area. The meteor and the effects of the airburst were extraordinarily well documented. Other events with comparable or larger energy in the past century or so include the 1963 August 3 bolide over the south Atlantic, for which only an infrasound signal was recorded, and the famous Tunguska impact in 1908. Estimates of the kinetic energy of the Tunguska impact range from 3 to 50 Mt, due to a lack of good observations at the time. The Chelyabinsk event is much better documented than both, and provides a unique opportunity to calibrate the different approaches used to model meteoroid entry and calculate the damaging effects of its airburst. Being able to predict better the potential damage on the ground from an impending small asteroid impact will help future impact hazard mitigation efforts. In order to be able to model the damaging effects of the Chelyabinsk airburst, the initial kinetic energy and approach trajectory needed to be known, how that energy was dissipated in the atmosphere, and what were the properties of the resulting airburst shockwave. Infrasonic waves are an important source of information about the fireball's initial kinetic energy. Further information about the kinetic energy is derived from the fireball's light curve. Analysis of video observations of the fireball and the shadows movements provided a meteor light curve, deceleration curve and trajectory. Video records also provided time of arrivals of the shockwave and much detail about how that shockwave interacted with surface structures. The extent of the glass damage was mapped by visiting over 50 villages in the area. Meteorites were analysed in a consortium study to understand how their material properties may have contributed to the fragmentation

  18. Structural Damage in Mexico City

    OpenAIRE

    Hall, John F; Beck, James L.

    1986-01-01

    This paper describes the structural damage in Mexico City caused by the September 19, 1985 earthquake. Photographs which illustrate various features of structural behavior are included. One explanation is presented as to why buildings with fundamental periods of elastic vibration considerably below the predominant two‐second period of the ground motion were most vulnerable to damage.

  19. Grounding Damage to Conventional Vessels

    DEFF Research Database (Denmark)

    Lützen, Marie; Simonsen, Bo Cerup

    2003-01-01

    The present paper is concerned with rational design of conventional vessels with regard to bottom damage generated in grounding accidents. The aim of the work described here is to improve the design basis, primarily through analysis of new statistical data for grounding damage. The current...

  20. Damage growth in aerospace composites

    CERN Document Server

    2015-01-01

    This book presents novel methods for the simulation of damage evolution in aerospace composites that will assist in predicting damage onset and growth and thus foster less conservative designs which realize the promised economic benefits of composite materials. The presented integrated numerical/experimental methodologies are capable of taking into account the presence of damage and its evolution in composite structures from the early phases of the design (conceptual design) through to the detailed finite element method analysis and verification phase. The book is based on the GARTEUR Research Project AG-32, which ran from 2007 to 2012, and documents the main results of that project. In addition, the state of the art in European projects on damage evolution in composites is reviewed. While the high specific strength and stiffness of composite materials make them suitable for aerospace structures, their sensitivity to damage means that designing with composites is a challenging task. The new approaches describ...

  1. DNA damage in neurodegenerative diseases

    Energy Technology Data Exchange (ETDEWEB)

    Coppedè, Fabio, E-mail: fabio.coppede@med.unipi.it; Migliore, Lucia, E-mail: lucia.migliore@med.unipi.it

    2015-06-15

    Highlights: • Oxidative DNA damage is one of the earliest detectable events in the neurodegenerative process. • The mitochondrial DNA is more vulnerable to oxidative attack than the nuclear DNA. • Cytogenetic damage has been largely documented in Alzheimer's disease patients. • The question of whether DNA damage is cause or consequence of neurodegeneration is still open. • Increasing evidence links DNA damage and repair with epigenetic phenomena. - Abstract: Following the observation of increased oxidative DNA damage in nuclear and mitochondrial DNA extracted from post-mortem brain regions of patients affected by neurodegenerative diseases, the last years of the previous century and the first decade of the present one have been largely dedicated to the search of markers of DNA damage in neuronal samples and peripheral tissues of patients in early, intermediate or late stages of neurodegeneration. Those studies allowed to demonstrate that oxidative DNA damage is one of the earliest detectable events in neurodegeneration, but also revealed cytogenetic damage in neurodegenerative conditions, such as for example a tendency towards chromosome 21 malsegregation in Alzheimer's disease. As it happens for many neurodegenerative risk factors the question of whether DNA damage is cause or consequence of the neurodegenerative process is still open, and probably both is true. The research interest in markers of oxidative stress was shifted, in recent years, towards the search of epigenetic biomarkers of neurodegenerative disorders, following the accumulating evidence of a substantial contribution of epigenetic mechanisms to learning, memory processes, behavioural disorders and neurodegeneration. Increasing evidence is however linking DNA damage and repair with epigenetic phenomena, thereby opening the way to a very attractive and timely research topic in neurodegenerative diseases. We will address those issues in the context of Alzheimer's disease

  2. DNA damage in neurodegenerative diseases

    International Nuclear Information System (INIS)

    Highlights: • Oxidative DNA damage is one of the earliest detectable events in the neurodegenerative process. • The mitochondrial DNA is more vulnerable to oxidative attack than the nuclear DNA. • Cytogenetic damage has been largely documented in Alzheimer's disease patients. • The question of whether DNA damage is cause or consequence of neurodegeneration is still open. • Increasing evidence links DNA damage and repair with epigenetic phenomena. - Abstract: Following the observation of increased oxidative DNA damage in nuclear and mitochondrial DNA extracted from post-mortem brain regions of patients affected by neurodegenerative diseases, the last years of the previous century and the first decade of the present one have been largely dedicated to the search of markers of DNA damage in neuronal samples and peripheral tissues of patients in early, intermediate or late stages of neurodegeneration. Those studies allowed to demonstrate that oxidative DNA damage is one of the earliest detectable events in neurodegeneration, but also revealed cytogenetic damage in neurodegenerative conditions, such as for example a tendency towards chromosome 21 malsegregation in Alzheimer's disease. As it happens for many neurodegenerative risk factors the question of whether DNA damage is cause or consequence of the neurodegenerative process is still open, and probably both is true. The research interest in markers of oxidative stress was shifted, in recent years, towards the search of epigenetic biomarkers of neurodegenerative disorders, following the accumulating evidence of a substantial contribution of epigenetic mechanisms to learning, memory processes, behavioural disorders and neurodegeneration. Increasing evidence is however linking DNA damage and repair with epigenetic phenomena, thereby opening the way to a very attractive and timely research topic in neurodegenerative diseases. We will address those issues in the context of Alzheimer's disease

  3. An Equilibrium Constitutive Model of Anisotropic Cartilage Damage to Elucidate Mechanisms of Damage Initiation and Progression.

    Science.gov (United States)

    Stender, Michael E; Regueiro, Richard A; Klisch, Stephen M; Ferguson, Virginia L

    2015-08-01

    Traumatic injuries and gradual wear-and-tear of articular cartilage (AC) that can lead to osteoarthritis (OA) have been hypothesized to result from tissue damage to AC. In this study, a previous equilibrium constitutive model of AC was extended to a constitutive damage articular cartilage (CDAC) model. In particular, anisotropic collagen (COL) fibril damage and isotropic glycosaminoglycan (GAG) damage were considered in a 3D formulation. In the CDAC model, time-dependent effects, such as viscoelasticity and poroelasticity, were neglected, and thus all results represent the equilibrium response after all time-dependent effects have dissipated. The resulting CDAC model was implemented in two different finite-element models. The first simulated uniaxial tensile loading to failure, while the second simulated spherical indentation with a rigid indenter displaced into a bilayer AC sample. Uniaxial tension to failure simulations were performed for three COL fibril Lagrangian failure strain (i.e., the maximum elastic COL fibril strain) values of 15%, 30%, and 45%, while spherical indentation simulations were performed with a COL fibril Lagrangian failure strain of 15%. GAG damage parameters were held constant for all simulations. Our results indicated that the equilibrium postyield tensile response of AC and the macroscopic tissue failure strain are highly dependent on COL fibril Lagrangian failure strain. The uniaxial tensile response consisted of an initial nonlinear ramp region due to the recruitment of intact fibrils followed by a rapid decrease in tissue stress at initial COL fibril failure, as a result of COL fibril damage which continued until ultimate tissue failure. In the spherical indentation simulation, damage to both the COL fibril and GAG constituents was located only in the superficial zone (SZ) and near the articular surface with tissue thickening following unloading. Spherical indentation simulation results are in agreement with published experimental

  4. High-Damage-Threshold Pinhole for Glass Fusion Laser Applications

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-06-07

    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{sup 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.

  5. 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.

  6. An improved damaging model for structured clays

    Institute of Scientific and Technical Information of China (English)

    姜岩; 雷华阳; 郑刚; 徐舜华

    2008-01-01

    An improved damaging model formulated within the framework of bounding surface for structured clays was proposed. The model was intended to describe the effects of structure degradation due to geotechnical loading. The predictive capability of the model was compared with those of triaxial compression test on Tianjin soft clays. The results show that, by incorporating a new damage function into the model, the reduction of elastic bulk and shear modulus with elastic deformations and the reduction of plastic bulk modulus and shear modulus with plastic deformations are able to be appreciable. Before the axial strain reaches 15%, the axial strain computed from the model is smaller than that from the test under the drained condition. Under the undrained condition, after the axial strain reaches 1%, the axial strain increases quickly because of the complete loss of structure and stiffness; and the result computed from the model is nearly equal to that from the model without the incorporation of the damage function due to less plastic strain under undrained condition test.

  7. Metrology to enable high temperature erosion testing - A new european initiative

    DEFF Research Database (Denmark)

    Fry, A.T.; Gee, M.G.; Clausen, Sønnik;

    2014-01-01

    an additional emission of 250,000 tonnes of CO2 over the lifetime of the plant [1]. The cause and type of solid particle erosion varies across different industries and locations in plant, for instance the particles could be volcanic ash in aero-engines, fly ash in boilers, exfoliated scale in steam turbines......The efficiency of high temperature energy generation plant and aero-engines is critically impacted by solid particle erosion, particularly at elevated temperatures. This damage process can reduce the efficiency of turbines by as much as 7 to 10%, and in the case of a large power plant cause...... or mineral matter in oil excavation. In all cases the performance of materials can be improved through better surface engineering and coatings, but the development of these is restricted due to lack of generic models, well controlled and instrumented tests and international standards. A framework is required...

  8. Generation of Scratches and Their Effects on Laser Damage Performance of Silica Glass

    Science.gov (United States)

    Li, Yaguo; Ye, Hui; Yuan, Zhigang; Liu, Zhichao; Zheng, Yi; Zhang, Zhe; Zhao, Shijie; Wang, Jian; Xu, Qiao

    2016-01-01

    Scratches are deleterious to precision optics because they can obscure and modulate incident laser light, which will increase the probability of damage to optical components. We here imitated the generation of brittle and ductile scratches during polishing process and endeavored to find out the possible influence of scratches on laser induced damage. Brittle scratches can be induced by spiking large sized abrasives and small abrasives may only generate ductile scratches. Both surface roughness and transmittivity are degraded due to the appearance of brittle scratches while ductile scratches make little difference to surface roughness and transmittance. However, ductile and brittle scratches greatly increase the density of damage about one order of magnitude relative to unscratched surface. In particular, ductile scratches also play an unignorable role in laser induced damage, which is different from previous knowledge. Furthermore, ZrO2 and Al2O3 polished surfaces appear to perform best in terms of damage density. PMID:27703218

  9. Clinical light damage to the eye

    Energy Technology Data Exchange (ETDEWEB)

    Miller, D.

    1987-01-01

    This book contains four sections: The Nature of Light and of Light Damage to Biological Tissues; Light Damage to the Eye; Protecting the Eye from Light Damage; and Overview of Light Damage to the Eye. Some of the paper titles are: Ultraviolet-Absorbing Intraocular Lens Implants; Phototoxic Changes in the Retina; Light Damage to the Lens; and Radiation, Light, and Sight.

  10. The distribution of subsurface damage in fused silica

    Energy Technology Data Exchange (ETDEWEB)

    Miller, P E; Suratwala, T I; Wong, L L; Feit, M D; Menapace, J A; Davis, P J; Steele, R A

    2005-11-21

    Managing subsurface damage during the shaping process and removing subsurface damage during the polishing process is essential in the production of low damage density optical components, such as those required for use on high peak power lasers. Removal of subsurface damage, during the polishing process, requires polishing to a depth which is greater than the depth of the residual cracks present following the shaping process. To successfully manage, and ultimately remove subsurface damage, understanding the distribution and character of fractures in the subsurface region introduced during fabrication process is important. We have characterized the depth and morphology of subsurface fractures present following fixed abrasive and loose abrasive grinding processes. At shallow depths lateral cracks and an overlapping series of trailing indentation fractures were found to be present. At greater depths, subsurface damage consists of a series of trailing indentation fractures. The area density of trailing fractures changes as a function of depth, however the length and shape of individual cracks remain nearly constant for a given grinding process. We have developed and applied a model to interpret the depth and crack length distributions of subsurface surface damage in terms of key variables including abrasive size and load.

  11. Infectious Keratitis: Secreted Bacterial Proteins That Mediate Corneal Damage

    Directory of Open Access Journals (Sweden)

    Mary E. Marquart

    2013-01-01

    Full Text Available Ocular bacterial infections are universally treated with antibiotics, which can eliminate the organism but cannot reverse the damage caused by bacterial products already present. The three very common causes of bacterial keratitis—Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae—all produce proteins that directly or indirectly cause damage to the cornea that can result in reduced vision despite antibiotic treatment. Most, but not all, of these proteins are secreted toxins and enzymes that mediate host cell death, degradation of stromal collagen, cleavage of host cell surface molecules, or induction of a damaging inflammatory response. Studies of these bacterial pathogens have determined the proteins of interest that could be targets for future therapeutic options for decreasing corneal damage.

  12. QUANTITATIVE STUDY ON GALVANIC EFFECTS DURING CAVITATION DAMAGE OF 1Cr13 STAINLESS STEEL

    Institute of Scientific and Technical Information of China (English)

    X.Bai; D.B.Sun; H.Y.Yu; X.L.Zhang

    2003-01-01

    The influence of the surface galvanic effects of 1Cr13 SS during cavitation damage hasbeen investigated in NaCl solutions. The results show that the solution concentrationand area ratio of bubble unacted surface to the bubble-acted surface greatly influencethe cavitation damage of the alloy. The surface galvanic effects can speed up thedissolution rate of the alloy, and the mass loss per area of the alloy increases linearlywith the area ratio of bubble unacted surface to the bubble acted surface of the alloy.

  13. BDS thin film damage competition

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, C J; Thomas, M D; Griffin, A J

    2008-10-24

    A laser damage competition was held at the 2008 Boulder Damage Symposium in order to determine the current status of thin film laser resistance within the private, academic, and government sectors. This damage competition allows a direct comparison of the current state-of-the-art of high laser resistance coatings since they are all tested using the same damage test setup and the same protocol. A normal incidence high reflector multilayer coating was selected at a wavelength of 1064 nm. The substrates were provided by the submitters. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials, and layer count will also be shared.

  14. Civil Liability for Environmental Damages

    Directory of Open Access Journals (Sweden)

    Daniela Ciochină

    2012-05-01

    Full Text Available We debated in this article the civil liability for environmental damages as stipulated in ourlegislation with reference to Community law. The theory of legal liability in environmental law is basedon the duty of all citizens to respect and protect the environment. Considering the importance ofenvironment in which we live, the liability for environmental damages is treated by the Constitution as aprinciple and a fundamental obligation. Many human activities cause environmental damages and, in linewith the principle of sustainable development, they should be avoided. However, when this is notpossible, they must be regulated (by criminal or administrative law in order to limit their adverse effectsand, according to the polluter pays principle, to internalize in advance their externalities (through taxes,insurances or other forms of financial security products. Communication aims to analyze these issues andlegal regulations dealing with the issue of liability for environmental damage.

  15. Climate change: Unattributed hurricane damage

    Science.gov (United States)

    Hallegatte, Stéphane

    2015-11-01

    In the United States, hurricanes have been causing more and more economic damage. A reanalysis of the disaster database using a statistical method that accounts for improvements in resilience opens the possibility that climate change has played a role.

  16. Probabilistic Fatigue Damage Program (FATIG)

    Science.gov (United States)

    Michalopoulos, Constantine

    2012-01-01

    FATIG computes fatigue damage/fatigue life using the stress rms (root mean square) value, the total number of cycles, and S-N curve parameters. The damage is computed by the following methods: (a) traditional method using Miner s rule with stress cycles determined from a Rayleigh distribution up to 3*sigma; and (b) classical fatigue damage formula involving the Gamma function, which is derived from the integral version of Miner's rule. The integration is carried out over all stress amplitudes. This software solves the problem of probabilistic fatigue damage using the integral form of the Palmgren-Miner rule. The software computes fatigue life using an approach involving all stress amplitudes, up to N*sigma, as specified by the user. It can be used in the design of structural components subjected to random dynamic loading, or by any stress analyst with minimal training for fatigue life estimates of structural components.

  17. Damage Atlas for Photographic materials

    Directory of Open Access Journals (Sweden)

    Kristel Van Camp

    2010-11-01

    Full Text Available La conservation des documents photographiques peut nécessiter des interventions préventives ou curatives. Ce choix est guidé par leur état de conservation. Une meilleure connaissance des détériorations est donc cruciale. Le répertoire présenté ici essaie de les classifier selon des caractéristiques spécifiques et leur niveau de gravité. Les différents types de dégradation sont illustrés et décrits avec une terminologie précise. L’auteur propose en regard de ceux-ci l’intervention qui semble la plus appropriée. Ce répertoire s’adresse à toutes les personnes concernées par la photographie, qu’ils soient dans le milieu de la conservation ou dans le domaine artistique, dans les musées ou dans les archives. In order to rescue a damaged photographic object, preventive or conservative actions are needed. Knowing the specific characteristics of different types of damage is crucial. A damage atlas can provide these characteristics. With this atlas the damage can be recognised and appropriate actions can be taken. This damage atlas offers a first attempt to such a characterisation in the field of photography. The damage atlas contains images and the necessary information about damage on photographic material. The atlas with special annotations about the terminology and the grade of the damage is meant for everybody who works with photographic material, as well in museums as in archives.

  18. How expensive is vole damage?

    OpenAIRE

    Walther, B; Fülling, O.; Malevez, J.; Pelz, H.-J.

    2008-01-01

    Vole species, especially Arvicola terrestris and Microtus arvalis cause significant economical damage in organic pomiculture by gnawing the root system of trees. The importance of voles as pest organisms is well known. Nevertheless, the estimation of financial loss caused by voles is difficult for German fruit growers. We conducted a survey among organic fruit growers to get data on kind and amount of annual damage. Using the available publications and official statistics we calculated econom...

  19. Nav Channels in Damaged Membranes.

    Science.gov (United States)

    Morris, C E; Joos, B

    2016-01-01

    Sick excitable cells (ie, Nav channel-expressing cells injured by trauma, ischemia, inflammatory, and other conditions) typically exhibit "acquired sodium channelopathies" which, we argue, reflect bleb-damaged membranes rendering their Nav channels "leaky." The situation is excitotoxic because untreated Nav leak exacerbates bleb damage. Fast Nav inactivation (a voltage-independent process) is so tightly coupled, kinetically speaking, to the inherently voltage-dependent process of fast activation that when bleb damage accelerates and thus left-shifts macroscopic fast activation, fast inactivation accelerates to the same extent. The coupled g(V) and availability(V) processes and their window conductance regions consequently left-shift by the same number of millivolts. These damage-induced hyperpolarizing shifts, whose magnitude increases with damage intensity, are called coupled left shift (CLS). Based on past work and modeling, we discuss how to test for Nav-CLS, emphasizing the virtue of sawtooth ramp clamp. We explain that it is the inherent mechanosensitivity of Nav activation that underlies Nav-CLS. Using modeling of excitability, we show the known process of Nav-CLS is sufficient to predict a wide variety of "sick excitable cell" phenomena, from hyperexcitability through to depolarizing block. When living cells are mimicked by inclusion of pumps, mild Nav-CLS produces a wide array of burst phenomena and subthreshold oscillations. Dynamical analysis of mild damage scenarios shows how these phenomena reflect changes in spike thresholds as the pumps try to counteract the leaky Nav channels. Smart Nav inhibitors designed for sick excitable cells would target bleb-damaged membrane, buying time for cell-mediated removal or repair of Nav-bearing membrane that has become bleb-damaged (ie, detached from the cytoskeleton). PMID:27586295

  20. Mechanism of DNA damage tolerance

    Institute of Scientific and Technical Information of China (English)

    Xin; Bi

    2015-01-01

    DNA damage may compromise genome integrity and lead to cell death. Cells have evolved a variety of processes to respond to DNA damage including damage repair and tolerance mechanisms, as well as damage checkpoints. The DNA damage tolerance(DDT) pathway promotes the bypass of single-stranded DNA lesions encountered by DNA polymerases during DNA replication. This prevents the stalling of DNA replication. Two mechanistically distinct DDT branches have been characterized. One is translesion synthesis(TLS) in which a replicative DNA polymerase is temporarily replaced by a specialized TLS polymerase that has the ability to replicate across DNA lesions. TLS is mechanistically simple and straightforward, but it is intrinsically error-prone. The other is the error-free template switching(TS) mechanism in which the stalled nascent strand switches from the damaged template to the undamaged newly synthesized sister strand for extension past the lesion. Error-free TS is a complex but preferable process for bypassing DNA lesions. However, our current understanding of this pathway is sketchy. An increasing number of factors are being found to participate or regulate this important mechanism, which is the focus of this editorial.

  1. Autologous transplantation of bone marrow mesenchymal stem cells to improve ocular surface in severely damaged cases%自体骨髓间充质干细胞移植改善重度眼表损伤临床观察

    Institute of Scientific and Technical Information of China (English)

    陈洁; 潘志强; 骆非; 接英; 彭秀军

    2011-01-01

    Objective To evaluate the effect of autologous bone marrow mesenchymal stem cells (BMSC) in treating severely damaged ocular surface.Methods Four cases of corneal chemical burn and two cases of Stenven-Johnson Syndrome were enrolled in this study.The BMSCs were obtained and cultured in vitro.The cells were harvested afler 14 days and confirmed to be BMSCs.Then the cells were placed on an amniotic membrane (AM) and expanded until 90% confluence formation before using.After the abnormal conjunctival and corneal tissues were removed from the cornea,the AM coated autologous BMSCs were transplanted onto the corneal surface.Aftersurgery,antibiotics,steroid and lubricant eye drops were used and patients were examined by slit-lamp and impression cytology.Results In all the six treated eyes,the entire corneal epithelium was intact one week after surgery.The visual acuity improved in three eyes,two eyes kept at the same level and decreased in one eye.The ocular surface was smooth,but the new blood vessels didn't show significant reduction.After twelve weeks,the epithelial cells phenotype and goblet cells appeared on corneal surface.Conclusions Autologous BMSCs can improve ocular surface condition in severely damaged patients,which show potential use for treating limbal deficiency.%目的 评价自体骨髓间充质干细胞在严重眼表损伤移植后的治疗效果.方法 选取了化学烧伤4例,Stevens-Johnson综合征2例.骨髓间充质干细胞取自患者,细胞培养14 d后,经细胞检测鉴定为骨髓间充质干细胞,将细胞种植在羊膜表面,细胞扩增融合达90%后使用.手术切除表面结膜化组织达角膜缘外3 mm,将羊膜上培养的自体骨髓间充质干细胞移植到角膜及角膜缘表面,术后予抗生素、激素、人工泪液点眼治疗;病人定期随访,进行裂隙灯显微镜及印迹细胞学检查.结果 6例患眼均覆盖了含有自体骨髓间充质干细胞的羊膜片,术后1周角膜上皮完整.3

  2. FINITE ELEMENT ANALYSIS ON EVOLUTION PROCESS FOR DAMAGE MICROCRACK HEALING

    Institute of Scientific and Technical Information of China (English)

    Huang Peizhen; Li Zhonghua; Sun Jun

    2000-01-01

    Based on the thermal kinetic and mass conservation, a series of controlling equations for the finite element are derived and related programs are developed to simulate the damage microcrack healing process controlled by surface diffusion. Two kinds of typical models for microcrack splitting are proposed, i.e., the grain boundary energy existing on the crack surface and residual stresses applying on the crack surface. And the conditions of microcrack splitting in the two models are given as a function of the microcrack aspect ratio. The microcrack with traction-free surfaces will directly evolve into a spheroid.

  3. 基于RVM回归误差补偿的航空发动机分布式控制系统多步预测控制%Multi-step predictive control for aero-engine distributed control system based on RVM regression error compensation

    Institute of Scientific and Technical Information of China (English)

    王磊; 谢寿生; 苗卓广; 任立通; 余坚

    2013-01-01

    针对具有随机有界双侧时延的航空发动机分布式控制系统,提出了一种基于多步预测和关联向量机(RVM)回归误差补偿的控制方案.首先建立航空发动机分布式控制系统(DCS)的神经网络非线性自回归滑动平均(NARMA)模型,利用当前的系统输出和控制量对N步之后的系统输出进行预测;其次用改进的RVM回归多步预测算法估计NARMA模型的的预测误差,并对预测结果进行误差补偿;最后利用补偿之后的预测值和设定值对控制参数进行滚动优化,设计系统的神经网络逆控制器实现系统的自适应控制.仿真结果证明该控制策略能够避免随机有界双侧时延对控制系统的影响,实现对设定值的稳定跟踪,且控制器具有较好的实时性和鲁棒性.低压转子转速阶跃响应的稳态绝对误差小于0.04%,响应时间小于0.3s.%A multi-step predictive control method based on relevance vector machine (RVM) regression error compensation was put forward to control aero-engine distributed control system (DCS) with stochastic and bounded time-delay.The neural network nonlinear auto regressive moving average (NARMA) model of the aero-engine DCS was established to predict the future output.An improved multi-step prognostic algorithm based on RVM regression was presented to estimate prognostic error series which were compensated for the NARMA model.Finally,a neural network inverse controller was designed,and rolling optimization of the parameters was conducted by prognostic output and the expectations.Simulation results illustrate the control strategy avoids the effect of stochastic and bounded time-delay on the control system.The controller has favorable dynamic tracking and robust performance.The absolute steady error of low-pressure rotor speed step response is less than 0.04%,and the response time is less than 0.3 s.

  4. Wavelength Dependence of Laser-Induced Bulk Damage Morphology in KDP Crystal: Determination of the Damage Formation Mechanism

    Institute of Scientific and Technical Information of China (English)

    HU Guo-Hang; ZHAO Yuan-An; LI Da-Wei; XIAO Qi-Ling

    2012-01-01

    Wet etch process is applied to expose the bulk damage sites in KDP crystals to the surface for the examination by scanning electron microscopy (SEM) and optical microscopy.The damage sites induced by 1064 nm laser consist of three distinct regions:a core,an outer region of modified material,and some oriented cracks.Laser irradiated with 355 nm results in an increase of damage density,a decrease of core diameter and,rarely,occurrence of the crack.WavelengKey Laboratory of Materials for High Power Laser,Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences,Shanghai 201800th dependence of the damage feature suggests that a repulsive force exists among the adjacent plasmas,which prevents further expansion of plasma and decreases the size of plasma. The deposited energy absorbed by the smaller plasma may not be able to generate the crack.

  5. Monitoring asphalt pavement damages using remote sensing techniques

    Science.gov (United States)

    Mettas, Christodoulos; Themistocleous, Kyriacos; Neocleous, Kyriacos; Christofe, Andreas; Pilakoutas, Kypros; Hadjimitsis, Diofantos

    2015-06-01

    One of the main issues in the maintenance plans of road agencies or governmental organizations is the early detection of damaged asphalt pavements. The development of a smart and non-destructive systematic technique for monitoring damaged asphalt pavements is considered a main priority to fill this gap. During the 1970's, remote sensing was used to map road surface distress, while during the last decade, remote sensing became more advanced, thereby assisting in the evolution of the identification and mapping of roads. Various techniques were used in order to explore condition, age, weaknesses and imperfections of asphalted pavements. These methods were fairly successful in the classification of asphalted surfaces and in the detection of some of their characteristics. This paper explores the state of the art of using remote sensing techniques for monitoring damaged pavements and some typical spectral profiles of various asphalt pavements in Cyprus area acquired using the SVC1024 field spectroradiometer.

  6. Contamination resistant coatings for enhanced laser damage thresholds

    Science.gov (United States)

    Weiller, Bruce H.; Fowler, Jesse D.; Villahermosa, Randy M.

    2012-11-01

    This paper describes a novel approach for the suppression of contamination enhanced laser damage to optical components by the use of fluorinated coatings that repel organic contaminates. In prior work we studied laser damage thresholds induced by ppm levels of toluene under nanosecond 1.064 μm irradiation of fused silica optics. That work showed that moderate vapor-phase concentrations (alcohols dramatically increased the laser damage threshold. The data are consistent with the hypothesis that water and alcohols interact more favorably with the hydroxylated silica surface thereby displacing toluene from the surface. In this work, preliminary results show that fluorinated self assembled monolayer coatings can be used to accomplish the same effect. Optics coated with fluorinated films have much higher survival rates compared with uncoated optics under the same conditions. In addition to enhancing survival of laser optics, these coatings have implications for protecting spacecraft imaging optics from organic contamination.

  7. Survey of four damage models for concrete.

    Energy Technology Data Exchange (ETDEWEB)

    Leelavanichkul, Seubpong (University of Utah, Salt Lake City, UT); Brannon, Rebecca Moss (University of Utah, Salt Lake City, UT)

    2009-08-01

    Four conventional damage plasticity models for concrete, the Karagozian and Case model (K&C), the Riedel-Hiermaier-Thoma model (RHT), the Brannon-Fossum model (BF1), and the Continuous Surface Cap Model (CSCM) are compared. The K&C and RHT models have been used in commercial finite element programs many years, whereas the BF1 and CSCM models are relatively new. All four models are essentially isotropic plasticity models for which 'plasticity' is regarded as any form of inelasticity. All of the models support nonlinear elasticity, but with different formulations. All four models employ three shear strength surfaces. The 'yield surface' bounds an evolving set of elastically obtainable stress states. The 'limit surface' bounds stress states that can be reached by any means (elastic or plastic). To model softening, it is recognized that some stress states might be reached once, but, because of irreversible damage, might not be achievable again. In other words, softening is the process of collapse of the limit surface, ultimately down to a final 'residual surface' for fully failed material. The four models being compared differ in their softening evolution equations, as well as in their equations used to degrade the elastic stiffness. For all four models, the strength surfaces are cast in stress space. For all four models, it is recognized that scale effects are important for softening, but the models differ significantly in their approaches. The K&C documentation, for example, mentions that a particular material parameter affecting the damage evolution rate must be set by the user according to the mesh size to preserve energy to failure. Similarly, the BF1 model presumes that all material parameters are set to values appropriate to the scale of the element, and automated assignment of scale-appropriate values is available only through an enhanced implementation of BF1 (called BFS) that regards scale effects to be coupled to

  8. Surface Water & Surface Drainage

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This data set contains boundaries for all surface water and surface drainage for the state of New Mexico. It is in a vector digital data structure digitized from a...

  9. DNA damage and repair mechanism. [DNA damage and repair mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Grossman, L.

    1976-01-01

    The ability of cells to survive in an environment specifically damaging to its DNA can be attributed to a variety of inherent repair mechanisms. This is a form of repair in which alterations are directly reversed to their original form. This reversibility is exemplified by the photoreactivation of ultraviolet-induced pyrimidine dimers. This phenomenon is attributable to the action of an enzyme, photolyase (photoreactivating enzyme), which is able to monomerize the uv-induced pyrimidine dimers in the presence of 320 to 370 nm light. Dilution of damage can be effected through a series of sister chromatid exchanges, controlled by recombinational mechanisms as a postreplication event. In this form of repair, replication proceeds to the point of damage, stops and resumes at the point of the next initiation site resulting in a gap in the newly synthesized daughter strand. It is presumed that those strands containing damaged regions exchange with undamaged regions of other DNA, strands, resulting in the eventual dilution of such damage.

  10. Effects of Vacuum of Fused Silica UV Damage

    Institute of Scientific and Technical Information of China (English)

    XU Shi-Zhen; LV Hai-Bing; YUAN Xiao-Dong; HUANG Jin; JIANG Xiao-Dong; WANG Hai-Jun; ZU Xiao-Tao; ZHENG Wan-Guo

    2008-01-01

    Damage points induced by 355 nm laser irradiation increase more quickly on the surface of fused silica in vacuum of about 10-3Pa than in atmospheric air at the same fluence.The larger concentration of point defects in vacuum is confirmed by photoluminescence intensity.X-ray photoelectron spectroscopy and infrared absorption indicate the formation of sub-stoichiometric sillca on the surface.The degradation mechanism of fused silica in vacuum is discussed.

  11. Damage Localization and Quantification of Earthquake Excited RC-Frames

    DEFF Research Database (Denmark)

    Skjærbæk, P.S.; Nielsen, Søren R.K.; Kirkegaard, Poul Henning;

    In the paper a recently proposed method for damage localization and quantification of RC-structures from response measurements is tested on experimental data. The method investigated requires at least one response measurement along the structure and the ground surface acceleration. Further, the t...

  12. Effect of defects on long-pulse laser-induced damage of two kinds of optical thin films.

    Science.gov (United States)

    Wang, Bin; Qin, Yuan; Ni, Xiaowu; Shen, Zhonghua; Lu, Jian

    2010-10-10

    In order to study the effect of defects on the laser-induced damage of different optical thin films, we carried out damage experiments on two kinds of thin films with a 1 ms long-pulse laser. Surface-defect and subsurface-defect damage models were used to explain the damage morphology. The two-dimensional finite element method was applied to calculate the temperature and thermal-stress fields of these two films. The results show that damages of the two films are due to surface and subsurface defects, respectively. Furthermore, the different dominant defects for thin films of different structures are discussed.

  13. Accumulated damage process of thermal sprayed coating under rolling contact by acoustic emission technique

    Science.gov (United States)

    Xu, Jia; Zhou, Zhen-yu; Piao, Zhong-yu

    2016-09-01

    The accumulated damage process of rolling contact fatigue (RCF) of plasma-sprayed coatings was investigated. The influences of surface roughness, loading condition, and stress cycle frequency on the accumulated damage status of the coatings were discussed. A ball-ondisc machine was employed to conduct RCF experiments. Acoustic emission (AE) technique was introduced to monitor the RCF process of the coatings. AE signal characteristics were investigated to reveal the accumulated damage process. Result showed that the polished coating would resist the asperity contact and remit accumulated damage. The RCF lifetime would then extend. Heavy load would aggravate the accumulated damage status and induce surface fracture. Wear became the main failure mode that reduced the RCF lifetime. Frequent stress cycle would aggravate the accumulated damage status and induce interface fracture. Fatigue then became the main failure mode that also reduced the RCF lifetime.

  14. Autophagy in DNA Damage Response

    Directory of Open Access Journals (Sweden)

    Piotr Czarny

    2015-01-01

    Full Text Available DNA damage response (DDR involves DNA repair, cell cycle regulation and apoptosis, but autophagy is also suggested to play a role in DDR. Autophagy can be activated in response to DNA-damaging agents, but the exact mechanism underlying this activation is not fully understood, although it is suggested that it involves the inhibition of mammalian target of rapamycin complex 1 (mTORC1. mTORC1 represses autophagy via phosphorylation of the ULK1/2–Atg13–FIP200 complex thus preventing maturation of pre-autophagosomal structures. When DNA damage occurs, it is recognized by some proteins or their complexes, such as poly(ADPribose polymerase 1 (PARP-1, Mre11–Rad50–Nbs1 (MRN complex or FOXO3, which activate repressors of mTORC1. SQSTM1/p62 is one of the proteins whose levels are regulated via autophagic degradation. Inhibition of autophagy by knockout of FIP200 results in upregulation of SQSTM1/p62, enhanced DNA damage and less efficient damage repair. Mitophagy, one form of autophagy involved in the selective degradation of mitochondria, may also play role in DDR. It degrades abnormal mitochondria and can either repress or activate apoptosis, but the exact mechanism remains unknown. There is a need to clarify the role of autophagy in DDR, as this process may possess several important biomedical applications, involving also cancer therapy.

  15. Catastrophic versus microscopic damage: applicability of laboratory measurements to real systems

    International Nuclear Information System (INIS)

    At ultraviolet wavelengths, damage to both coatings and bare surfaces is dominated by the presence of discrete localized defects. During multiple-shot irradition, the overwhelming majority of these defects are damaged by the first or first few shots. Initially, damage morphology is that of a crater of approximately 10 microns in diameter; however, upon continued irradiation, one of two events can occur; either the crater grows to catastrophic dimensions or it remains unchanged. In the latter case, the damage is only observable under a microscope, it may be indistinguishable from cosmetic defects before irradiation, and it is likely that any related degradation in optical performance is unmeasurable. In view of the generally accepted definition of laser damage (i.e. any visible change in the surface), it is important to consider the implications for real systems. These are discussed in the context of ultraviolet test results for both coatings and surfaces

  16. QUANTITATIVE STUDY ON GALVANIC EFFECTS DURING CAVITATION DAMAGE OF 1Cr13 STAINLESS STEEL

    Institute of Scientific and Technical Information of China (English)

    X.Bai; D.B.Sun; 等

    2003-01-01

    The influence of the surface galvanic effects of 1Cr13 SS during cavitation damage has been investigated in NaCl soutions.The results show that the solution concentration and area ratio of bubble unacted surface to the bubble-acted surface greatly influence the cavitation damage of the alloy.The surace galvanic effects can speed up the dissolution rate of the alloy,and the mass loss per area of the alloy increases linearly with the area ratio of bubble unacted surface to the bubble acted surface of the alloy.

  17. The CATDAT damaging earthquakes database

    Science.gov (United States)

    Daniell, J. E.; Khazai, B.; Wenzel, F.; Vervaeck, A.

    2011-08-01

    The global CATDAT damaging earthquakes and secondary effects (tsunami, fire, landslides, liquefaction and fault rupture) database was developed to validate, remove discrepancies, and expand greatly upon existing global databases; and to better understand the trends in vulnerability, exposure, and possible future impacts of such historic earthquakes. Lack of consistency and errors in other earthquake loss databases frequently cited and used in analyses was a major shortcoming in the view of the authors which needed to be improved upon. Over 17 000 sources of information have been utilised, primarily in the last few years, to present data from over 12 200 damaging earthquakes historically, with over 7000 earthquakes since 1900 examined and validated before insertion into the database. Each validated earthquake includes seismological information, building damage, ranges of social losses to account for varying sources (deaths, injuries, homeless, and affected), and economic losses (direct, indirect, aid, and insured). Globally, a slightly increasing trend in economic damage due to earthquakes is not consistent with the greatly increasing exposure. The 1923 Great Kanto (214 billion USD damage; 2011 HNDECI-adjusted dollars) compared to the 2011 Tohoku (>300 billion USD at time of writing), 2008 Sichuan and 1995 Kobe earthquakes show the increasing concern for economic loss in urban areas as the trend should be expected to increase. Many economic and social loss values not reported in existing databases have been collected. Historical GDP (Gross Domestic Product), exchange rate, wage information, population, HDI (Human Development Index), and insurance information have been collected globally to form comparisons. This catalogue is the largest known cross-checked global historic damaging earthquake database and should have far-reaching consequences for earthquake loss estimation, socio-economic analysis, and the global reinsurance field.

  18. The CATDAT damaging earthquakes database

    Directory of Open Access Journals (Sweden)

    J. E. Daniell

    2011-08-01

    Full Text Available The global CATDAT damaging earthquakes and secondary effects (tsunami, fire, landslides, liquefaction and fault rupture database was developed to validate, remove discrepancies, and expand greatly upon existing global databases; and to better understand the trends in vulnerability, exposure, and possible future impacts of such historic earthquakes.

    Lack of consistency and errors in other earthquake loss databases frequently cited and used in analyses was a major shortcoming in the view of the authors which needed to be improved upon.

    Over 17 000 sources of information have been utilised, primarily in the last few years, to present data from over 12 200 damaging earthquakes historically, with over 7000 earthquakes since 1900 examined and validated before insertion into the database. Each validated earthquake includes seismological information, building damage, ranges of social losses to account for varying sources (deaths, injuries, homeless, and affected, and economic losses (direct, indirect, aid, and insured.

    Globally, a slightly increasing trend in economic damage due to earthquakes is not consistent with the greatly increasing exposure. The 1923 Great Kanto ($214 billion USD damage; 2011 HNDECI-adjusted dollars compared to the 2011 Tohoku (>$300 billion USD at time of writing, 2008 Sichuan and 1995 Kobe earthquakes show the increasing concern for economic loss in urban areas as the trend should be expected to increase. Many economic and social loss values not reported in existing databases have been collected. Historical GDP (Gross Domestic Product, exchange rate, wage information, population, HDI (Human Development Index, and insurance information have been collected globally to form comparisons.

    This catalogue is the largest known cross-checked global historic damaging earthquake database and should have far-reaching consequences for earthquake loss estimation, socio-economic analysis, and the global

  19. Interacting damage models mapped onto ising and percolation models

    Energy Technology Data Exchange (ETDEWEB)

    Toussaint, Renaud; Pride, Steven R.

    2004-03-23

    The authors introduce a class of damage models on regular lattices with isotropic interactions between the broken cells of the lattice. Quasistatic fiber bundles are an example. The interactions are assumed to be weak, in the sense that the stress perturbation from a broken cell is much smaller than the mean stress in the system. The system starts intact with a surface-energy threshold required to break any cell sampled from an uncorrelated quenched-disorder distribution. The evolution of this heterogeneous system is ruled by Griffith's principle which states that a cell breaks when the release in potential (elastic) energy in the system exceeds the surface-energy barrier necessary to break the cell. By direct integration over all possible realizations of the quenched disorder, they obtain the probability distribution of each damage configuration at any level of the imposed external deformation. They demonstrate an isomorphism between the distributions so obtained and standard generalized Ising models, in which the coupling constants and effective temperature in the Ising model are functions of the nature of the quenched-disorder distribution and the extent of accumulated damage. In particular, they show that damage models with global load sharing are isomorphic to standard percolation theory, that damage models with local load sharing rule are isomorphic to the standard ising model, and draw consequences thereof for the universality class and behavior of the autocorrelation length of the breakdown transitions corresponding to these models. they also treat damage models having more general power-law interactions, and classify the breakdown process as a function of the power-law interaction exponent. Last, they also show that the probability distribution over configurations is a maximum of Shannon's entropy under some specific constraints related to the energetic balance of the fracture process, which firmly relates this type of quenched-disorder based

  20. 7 CFR 51.2852 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.2852 Section 51.2852 Agriculture... Serious damage. Serious damage means any specific defect described in this section; or any equally... specific defects shall be considered as serious damage: (a) Watery scales when more than the equivalent...

  1. 7 CFR 51.2090 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.2090 Section 51.2090 Agriculture... Standards for Grades of Almonds in the Shell Definitions § 51.2090 Serious damage. Serious damage means any..., rancidity, insect injury and damage by mold. The following defect shall be considered as serious...

  2. 7 CFR 51.3067 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.3067 Section 51.3067 Agriculture... Standards for Florida Avocados Definitions § 51.3067 Serious damage. Serious damage means any defect which... serious damage: (a) Anthracnose when any spot exceeds the area of a circle one-fourth inch in diameter,...

  3. 7 CFR 51.2966 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.2966 Section 51.2966 Agriculture... Standards for Grades of Walnuts in the Shell Definitions § 51.2966 Serious damage. Serious damage means any... serious damage: (a) Discoloration (or stain) which covers, in the aggregate, one-third or more of...

  4. 7 CFR 51.1913 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.1913 Section 51.1913 Agriculture... Consumer Standards for Fresh Tomatoes Definitions § 51.1913 Serious damage. Serious damage means any defect... allowed for any one defect, shall be considered as serious damage: (a) Soft ripe tomatoes or...

  5. Material Induced Anisotropic Damage in DP600

    NARCIS (Netherlands)

    Niazi, M.S.; Wisselink, H.H.; Meinders, V.T.; Boogaard, van den A.H.

    2013-01-01

    Plasticity induced damage development in metals is anisotropic by nature. The anisotropy in damage is driven by two different phenomena; anisotropic deformation state i.e. Load Induced Anisotropic Damage (LIAD) and anisotropic microstructure i.e. Material Induced Anisotropic Damage (MIAD). The contr

  6. Nonlinear cumulative damage model for multiaxial fatigue

    Institute of Scientific and Technical Information of China (English)

    SHANG De-guang; SUN Guo-qin; DENG Jing; YAN Chu-liang

    2006-01-01

    On the basis of the continuum fatigue damage theory,a nonlinear uniaxial fatigue cumulative damage model is first proposed.In order to describe multiaxial fatigue damage characteristics,a nonlinear multiaxial fatigue cumulative damage model is developed based on the critical plane approach,The proposed model can consider the multiaxial fatigue limit,mean hydrostatic pressure and the unseparated characteristic for the damage variables and loading parameters.The recurrence formula of fatigue damage model was derived under multilevel loading,which is used to predict multiaxial fatigue life.The results showed that the proposed nonlinear multiaxial fatigue cumulative damage model is better than Miner's rule.

  7. The Damage Law of HTPB Propellant under Thermomechanical Loading

    Science.gov (United States)

    Liu, Cheng-wu; Yang, Jian-hong; Wang, Xian-meng; Ma, Yong-kang

    2016-01-01

    By way of measuring the acoustic emission (AE) signals of Hydroxyl-terminated polybutadiene (HTPB) propellant in condition of uniform speed, and combined with the scanning electron microscopy (SEM) fracture surface observation, the damage law of HTPB composite solid propellant under thermomechanical loading was studied. The results show that the effects of thermomechanical loading on HTPB propellant are related to the time and can be divided into three different stages. In the first stage, thermal air aging dominates; in the second stage, interface damage is dominant; and in the third stage, thermal air aging is once again dominant.

  8. Nondestructive Evaluation of Damage in Concrete Under Uniaxial Compression

    Science.gov (United States)

    Shokouhi, P.; Zoëga, A.; Wiggenhauser, H.

    2010-02-01

    Surface wave velocities over the sonic frequency range (<20 KHz) were measured on concrete specimens undergoing various cycles of loading and unloading. Acoustic Emission test (AE) was conducted simultaneously to monitor the microcracking activities. The sonic surface wave velocity was found to be highly stress-dependent. The observed changes in surface wavespeed are repeatable and follow a particular trend. By measuring the wave velocities in both loading and unloading phases, the effects of stress and stress-induced damages could be distinguished. The observed trend could be explained by a combination of acoustoelasticity and microcracking theories.

  9. Damage Propagation Modeling for Aircraft Engine Prognostics

    Science.gov (United States)

    Saxena, Abhinav; Goebel, Kai; Simon, Don; Eklund, Neil

    2008-01-01

    This paper describes how damage propagation can be modeled within the modules of aircraft gas turbine engines. To that end, response surfaces of all sensors are generated via a thermo-dynamical simulation model for the engine as a function of variations of flow and efficiency of the modules of interest. An exponential rate of change for flow and efficiency loss was imposed for each data set, starting at a randomly chosen initial deterioration set point. The rate of change of the flow and efficiency denotes an otherwise unspecified fault with increasingly worsening effect. The rates of change of the faults were constrained to an upper threshold but were otherwise chosen randomly. Damage propagation was allowed to continue until a failure criterion was reached. A health index was defined as the minimum of several superimposed operational margins at any given time instant and the failure criterion is reached when health index reaches zero. Output of the model was the time series (cycles) of sensed measurements typically available from aircraft gas turbine engines. The data generated were used as challenge data for the Prognostics and Health Management (PHM) data competition at PHM 08.

  10. Engineering Polymer Blends for Impact Damage Mitigation

    Science.gov (United States)

    Gordon, Keith L.; Smith, Russell W.; Working, Dennis C.; Siochi, Emilie J.

    2016-01-01

    Structures containing polymers such as DuPont's Surlyn® 8940, demonstrate puncture healing when impacted by a 9 millimeter projectile traveling from speeds near 300 meters per second (1,100 feet per second) to hypervelocity impacts in the micrometeoroid velocity range of 5 kilometers per second (16,000 feet per second). Surlyn® 8940 puncture heals over a temperature range of minus 30 degrees Centigrade to plus 70 degrees Centigrade and shows potential for use in pressurized vessels subject to impact damage. However, such polymers are difficult to process and limited in applicability due to their low thermal stability, poor chemical resistance and overall poor mechanical properties. In this work, several puncture healing engineered melt formulations were developed. Moldings of melt blend formulations were impacted with a 5.56 millimeter projectile with a nominal velocity of 945 meters per second (3,100 feet per second) at about 25 degrees Centigrade, 50 degrees Centigrade and 100 degrees Centigrade, depending upon the specific blend being investigated. Self-healing tendencies were determined using surface vacuum pressure tests and tensile tests after penetration using tensile dog-bone specimens (ASTM D 638-10). For the characterization of tensile properties both pristine and impacted specimens were tested to obtain tensile modulus, yield stress and tensile strength, where possible. Experimental results demonstrate a range of new puncture healing blends which mitigate damage in the ballistic velocity regime.

  11. Darlington NGS fuel damage investigation

    International Nuclear Information System (INIS)

    An investigation of the fuel damage at Darlington Nuclear Generating Station employed various measuring, modelling, and inspection techniques to establish that fretting and fatigue were caused by 150 Hz vibration from the primary heat transport pumps. The problem has since been corrected, and the units have been returned to service. 3 figs

  12. Modeling EMP damage to semiconductors

    International Nuclear Information System (INIS)

    Mechanisms that can cause damage to P-N junction devices in an electromagnetic pulse (EMP) environment were examined along with existing models for these mechanisms, with the objective of developing models that can accurately predict the input power threshold for device failure

  13. Compensation for oil pollution damage

    Science.gov (United States)

    Matugina, E. G.; Glyzina, T. S.; Kolbysheva, Yu V.; Klyuchnikov, A. S.; Vusovich, O. V.

    2015-11-01

    The commitment of national industries to traditional energy sources, as well as constantly growing energy demand combined with adverse environmental impact of petroleum production and transportation urge to establish and maintain an appropriate legal and administrative framework for oil pollution damage compensation. The article considers management strategies for petroleum companies that embrace not only production benefits but also environmental issues.

  14. A review of thermographic techniques for damage investigation in composites

    Directory of Open Access Journals (Sweden)

    Laura Vergani

    2014-01-01

    Full Text Available The aim of this work is a review of scientific results in the literature, related to the application of thermographic techniques to composite materials. Thermography is the analysis of the surface temperature of a body by infrared rays detection via a thermal-camera. The use of this technique is mainly based on the modification of the surface temperature of a material, when it is stimulated by means of a thermal or mechanical external source. The presence of defects, in fact, induces a localized variation in its temperature distribution and, then, the measured values of the surface temperature can be used to localize and evaluate the dimensions and the evolution of defects. In the past, many applications of thermography were proposed on homogeneous materials, but only recently this technique has also been extended to composites. In this work several applications of thermography to fibres reinforced plastics are presented. Thermographic measurements are performed on the surface of the specimens, while undergoing static and dynamic tensile loading. The joint analysis of thermal and mechanical data allows one to assess the damage evolution and to study the damage phenomenon from both mechanical and energetic viewpoints. In particular, one of the main issues is to obtain information about the fatigue behaviour of composite materials, by following an approach successfully applied to homogenous materials. This approach is based on the application of infrared thermography on specimens subjected to static or stepwise dynamic loadings and on the definition of a damage stress, D, that is correlated to the fatigue strength of the material. A wide series of experimental fatigue tests has been carried out to verify if the value of the damage stress, D, is correlated with the fatigue strength of the material. The agreement between the different values is good, showing the reliability of the presented thermographic techniques, to the study of composite

  15. Damage Propagation Modeling for Aircraft Engine Run-to-Failure Simulation

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper describes how damage propagation can be modeled within the modules of aircraft gas turbine engines. To that end, response surfaces of all sensors are...

  16. Modeling of Corrosion-induced Concrete Damage

    DEFF Research Database (Denmark)

    Thybo, Anna Emilie A.; Michel, Alexander; Stang, Henrik

    2013-01-01

    In the present paper a finite element model is introduced to simulate corrosion-induced damage in concrete. The model takes into account the penetration of corrosion products into the concrete as well as non-uniform formation of corrosion products around the reinforcement. To ac-count for the non......-uniform formation of corrosion products at the concrete/reinforcement interface, a deterministic approach is used. The model gives good estimates of both deformations in the con-crete/reinforcement interface and crack width when compared to experimental data. Further, it is shown that non-uniform deposition...... of corrosion products affects both the time-to cover cracking and the crack width at the concrete surface....

  17. Elastic properties, strength and damage tolerance of pultruded composites

    Science.gov (United States)

    Saha, Mrinal Chandra

    parameters were measured in the form of dent depth, back surface crack length, and damage area. The compression tests were performed, using an end-gripped compression test fixture, on both the damaged specimens and open-hole specimens. A relationship between the compressive strength and hole-diameter was established. The compressive strength of damaged specimens was compared to determine the "equivalent-hole-diameter." A correlation between damage parameters and the "equivalent-hole-diameter" was established to find a parameter that could be used as a measure of damage resistance and damage tolerance of pultruded composite structures.

  18. Analysis of damage caused by siloxanes in stationary reciprocating internal combustion engines operating with landfill gas

    OpenAIRE

    Álvarez Flórez, Jesús Andrés; Egusquiza Estévez, Eduard

    2015-01-01

    Failures in reciprocating internal combustion engines operating with landfill gas are not uncommon. In general, damage is located in the combustion chamber surfaces and in the ring grooves, where a layer of non-volatile combustion products is deposited. These deposits attached to the surfaces reduce heat transfer and increase inner temperature, which produces a knocking phenomena damaging the crank bearings and fusing of the piston head material. Lubrication problems also appear due to ...

  19. Implementation of an anisotropic damage material model using general second order damage tensor

    NARCIS (Netherlands)

    Niazi, Muhammad; Wisselink, Harm; Meinders, Timo; Horn, ten Carel; Mori, K.; Pietrzyk, M.; Kusiak, J.; Majta, J.; Hartley, P.; Lin, J.

    2010-01-01

    Damage in metals is mainly the process of the initiation and growth of voids. With the growing complexity in materials and forming proc-esses, it becomes inevitable to include anisotropy in damage (tensorial damage variable). Most of the anisotropic damage models define the damage tensor in the prin

  20. Explosive-induced shock damage in copper and recompression of the damaged region

    Science.gov (United States)

    Turley, W. D.; Stevens, G. D.; Hixson, R. S.; Cerreta, E. K.; Daykin, E. P.; Graeve, O. A.; La Lone, B. M.; Novitskaya, E.; Perez, C.; Rigg, P. A.; Veeser, L. R.

    2016-08-01

    We have studied the dynamic spall process for copper samples in contact with detonating low-performance explosives. When a triangular shaped shock wave from detonation moves through a sample and reflects from the free surface, tension develops immediately, one or more damaged layers can form, and a spall scab can separate from the sample and move ahead of the remaining target material. For dynamic experiments, we used time-resolved velocimetry and x-ray radiography. Soft-recovered samples were analyzed using optical imaging and microscopy. Computer simulations were used to guide experiment design. We observe that for some target thicknesses the spall scab continues to run ahead of the rest of the sample, but for thinner samples, the detonation product gases accelerate the sample enough for it to impact the spall scab several microseconds or more after the initial damage formation. Our data also show signatures in the form of a late-time reshock in the time-resolved data, which support this computational prediction. A primary goal of this research was to study the wave interactions and damage processes for explosives-loaded copper and to look for evidence of this postulated recompression event. We found both experimentally and computationally that we could tailor the magnitude of the initial and recompression shocks by varying the explosive drive and the copper sample thickness; thin samples had a large recompression after spall, whereas thick samples did not recompress at all. Samples that did not recompress had spall scabs that completely separated from the sample, whereas samples with recompression remained intact. This suggests that the hypothesized recompression process closes voids in the damage layer or otherwise halts the spall formation process. This is a somewhat surprising and, in some ways controversial, result, and the one that warrants further research in the shock compression community.

  1. Laser induced damage of fused silica polished optics due to a droplet forming organic contaminant

    Energy Technology Data Exchange (ETDEWEB)

    Bien-Aime, Karell; Neauport, Jerome; Tovena-Pecault, Isabelle; Fargin, Evelyne; Labrugere, Christine; Belin, Colette; Couzi, Michel

    2009-04-20

    We report on the effect of organic molecular contamination on single shot laser induced damage density at the wavelength of 351 nm, with a 3 ns pulse length. Specific contamination experiments were made with dioctylphthalate (DOP) in liquid or gaseous phase, on the surface of fused silica polished samples, bare or solgel coated. Systematic laser induced damage was observed only in the case of liquid phase contamination. Different chemical and morphological characterization methods were used to identify and understand the damage process. We demonstrate that the contaminant morphology, rather than its physicochemical nature, can be responsible for the decrease of laser induced damage threshold of optics.

  2. Laser induced damage of fused silica polished optics due to a droplet forming organic contaminant.

    Science.gov (United States)

    Bien-Aimé, Karell; Néauport, Jérome; Tovena-Pecault, Isabelle; Fargin, Evelyne; Labrugère, Christine; Belin, Colette; Couzi, Michel

    2009-04-20

    We report on the effect of organic molecular contamination on single shot laser induced damage density at the wavelength of 351 nm, with a 3 ns pulse length. Specific contamination experiments were made with dioctylphthalate (DOP) in liquid or gaseous phase, on the surface of fused silica polished samples, bare or solgel coated. Systematic laser induced damage was observed only in the case of liquid phase contamination. Different chemical and morphological characterization methods were used to identify and understand the damage process. We demonstrate that the contaminant morphology, rather than its physicochemical nature, can be responsible for the decrease of laser induced damage threshold of optics. PMID:19381171

  3. Nondestructive Investigation of Stress-Induced Damage in Concrete

    Directory of Open Access Journals (Sweden)

    P. Shokouhi

    2010-01-01

    Full Text Available The changes in the sonic surface wave velocity of concrete under stress were investigated in this paper. Surface wave velocities at sonic frequency range were measured on a prismatic concrete specimen undergoing several cycles of uniaxial compression. The loading was applied (or removed gradually in predefined small steps (stress-controlled. The surface wave velocity was measured at every load step during both loading and unloading phases. Acoustic Emission (AE test was conducted simultaneously to monitor the microcracking activities at different levels of loading. It was found that the sonic surface wave velocity is highly stress dependent and the velocity-stress relationship follows a particular trend. The observed trend could be explained by a combination of acoustoelasticity and microcracking theories, each valid over a certain range of applied stresses. Having measured the velocities while unloading, when the material suffers no further damage, the effect of stress and damage could be differentiated. The slope of the velocity-stress curves over the elastic region was calculated for different load cycles. This quantity was normalized to yield a dimensionless nonlinear parameter. This parameter generally increases with the level of induced damage in concrete.

  4. Surfactant damages on coastal vegetation in southern Italy

    Directory of Open Access Journals (Sweden)

    2005-01-01

    Full Text Available Coastal vegetation decline caused by seaspray has been reported to affect a variety of species in several countries: Australia, South of France, along the Italian Tyrrhenian coast, Spain and Tunisia. The most serious injury is due to the interaction between sea salt and surfactants, even if surfactants may cause direct damage on cell membranes. The salt uptake is enhanced by the durfactant-induced erosion of the epicuticular wax, which reduces the water surface tension. The symptoms are non-specific and consist in leaf discoloration and necrosis. In needles, necrosis begins from the apex; in leaves, from the edges. Directionality of crown damage is the main symptom for diagnosing the involvement of polluted seaspray. If an obstacle is placed between trees and sea wind, the trees do not show appreciable damage. In Italy, the tree decline caused by seaspray and surfactants has been investigated with special reference to the pinewoods of the San Rossore (Tuscany, Central Italy, or on the Tyrrhenian coastlands of Central Italy, such as the area around Castelporziano in Lazio. This research is aimed at a preliminary assessment of the extent of surfactant damage to the coastal vegetation in four regions in Southern Italy by: i field surveys and mapping of damage caused by surfactants; ii detecting the presence of surfactants on the tree crowns. The damages have been observed in a lot of zones in Apulia, Basilicata, Campania and Calabria, within 500 m inland from the sea, for a maximum length of 5500 m coastline, near the mouth of a river or stream, near the outlet of sewage canals and in any other coastal areas where the surface currents carry a surfactant load.

  5. Electrical impedance tomography-based sensing skin for quantitative imaging of damage in concrete

    International Nuclear Information System (INIS)

    This paper outlines the development of a large-area sensing skin for damage detection in concrete structures. The developed sensing skin consists of a thin layer of electrically conductive copper paint that is applied to the surface of the concrete. Cracking of the concrete substrate results in the rupture of the sensing skin, decreasing its electrical conductivity locally. The decrease in conductivity is detected with electrical impedance tomography (EIT) imaging. In previous works, electrically based sensing skins have provided only qualitative information on the damage on the substrate surface. In this paper, we study whether quantitative imaging of the damage is possible. We utilize application-specific models and computational methods in the image reconstruction, including a total variation (TV) prior model for the damage and an approximate correction of the modeling errors caused by the inhomogeneity of the painted sensing skin. The developed damage detection method is tested experimentally by applying the sensing skin to polymeric substrates and a reinforced concrete beam under four-point bending. In all test cases, the EIT-based sensing skin provides quantitative information on cracks and/or other damages on the substrate surface: featuring a very low conductivity in the damage locations, and a reliable indication of the lengths and shapes of the cracks. The results strongly support the applicability of the painted EIT-based sensing skin for damage detection in reinforced concrete elements and other substrates. (paper)

  6. Combination resonance of aero-engine compressor blade with a breathing crack under displacement excitation of rotor shaft%受转子位移激励的航空压气机呼吸裂纹叶片的联合共振

    Institute of Scientific and Technical Information of China (English)

    韩刚; 陈予恕

    2015-01-01

    The amplitude-frequency response of combination resonance of an aero-engine compressor blade with a breathing crack under the lateral displacement excitation of the rotor shaft was investigated.The blade was simplified into a single degree of freedom system using Galerkin’s method.The first order equation of the resonance response under parametric excitation combining with displacement excitation was derived by using the multi-scale method.The effects of the opening and closing depth of crack,the location of lateral section with crack and the displacement amplitude of rotor shaft on the amplitude-frequency response of resonance were analyzed.The obtained results show that controlling the changes of the above mentioned parameters which are of great influence on the dynamic behavior is an effective measure for preventing fatigue of the blade.%研究了航空压气机呼吸裂纹叶片在转子位移激励下的联合共振幅频响应的变化规律;叶片连续体模型采用伽辽金法简化成单自由度的系统模型,通过多尺度法导出了叶片在参数激励与位移激励联合作用下的共振幅频响应的一阶近似方程;分析了裂纹的开合深度、裂纹所在截面的位置以及转子在垂直与水平方向上的位移幅值差对幅频响应的影响;数值结果表明以上三个物理参数是促使叶片动力学行为发生变化的敏感参数,控制这三个物理参数的变化是有效防止叶片进一步破坏的根本途径。

  7. Radiation damage in biomolecular systems

    CERN Document Server

    Fuss, Martina Christina

    2012-01-01

    Since the discovery of X-rays and radioactivity, ionizing radiations have been widely applied in medicine both for diagnostic and therapeutic purposes. The risks associated with radiation exposure and handling led to the parallel development of the field of radiation protection. Pioneering experiments done by Sanche and co-workers in 2000 showed that low-energy secondary electrons, which are abundantly generated along radiation tracks, are primarily responsible for radiation damage through successive interactions with the molecular constituents of the medium. Apart from ionizing processes, which are usually related to radiation damage, below the ionization level low-energy electrons can induce molecular fragmentation via dissociative processes such as internal excitation and electron attachment. This prompted collaborative projects between different research groups from European countries together with other specialists from Canada,  the USA and Australia. This book summarizes the advances achieved by these...

  8. A damage model for fracking

    CERN Document Server

    Norris, J Quinn; Rundle, John B

    2015-01-01

    Injections of large volumes of water into tight shale reservoirs allows the extraction of oil and gas not previously accessible. This large volume "super" fracking induces damage that allows the oil and/or gas to flow to an extraction well. The purpose of this paper is to provide a model for understanding super fracking. We assume that water is injected from a small spherical cavity into a homogeneous elastic medium. The high pressure of the injected water generates hoop stresses that reactivate natural fractures in the tight shales. These fractures migrate outward as water is added creating a spherical shell of damaged rock. The porosity associated with these fractures is equal to the water volume injected. We obtain an analytic expression for this volume. We apply our model to a typical tight shale reservoir and show that the predicted water volumes are in good agreement with the volumes used in super fracking.

  9. Comparative study of approaches to assess damage in thermally fatigued Cusbnd Crsbnd Zr alloy

    Science.gov (United States)

    Chatterjee, Arya; Mitra, R.; Chakraborty, A. K.; Rotti, C.; Ray, K. K.

    2016-06-01

    For the first time the nature of response of thermal fatigue damage (TFD) in Cusbnd Crsbnd Zr alloys, considered for the High Heat Flux components of Tokamak and its subsystems in International Thermonuclear Experimental Reactor application has been studied. Temperature cycling between 290 °C and 30 °C, similar to the service condition, has been carried out on two differently aged Cusbnd Crsbnd Zr alloys. The TFD has been assessed by damage mechanics approach using damage parameters, and by surface characteristics. The damage parameters increase exponentially during initial fatigue cycles and saturates, whilst surface characteristics shows continuous increase with increase in thermal fatigue cycles. Damages are different in the aged alloys depending upon the aging conditions.

  10. Damage Detection of a Continuous Bridge from Response of a Moving Vehicle

    OpenAIRE

    Li, Z. H.; Au, F. T. K.

    2014-01-01

    This paper presents a multi-stage multi-pass method to identify the location of damage of a continuous bridge from the vertical response of a moving vehicle. The damage can be detected from this response by some existing methods if the road surface of the bridge is smooth, which implies that the vibration of the vehicle contains information of the damage. The detection becomes difficult if the road surface of the bridge is rough as it will affect the response of the vehicle and may mask the i...

  11. Optimum inductively coupled plasma etching of fused silica to remove subsurface damage layer

    Science.gov (United States)

    Jiang, Xiaolong; Liu, Ying; Liu, Zhengkun; Qiu, Keqiang; Xu, Xiangdong; Hong, Yilin; Fu, Shaojun

    2015-11-01

    In this work, we introduce an optimum ICP etching technique that successfully removes the subsurface damage (SSD) layer of fused silica without causing plasma induced surface damage (PISD) or lateral etching of SSD. As one of the commonest PISD initiators, metal contamination from reactor chamber is prevented by employing a simple isolation device. Based on this device, a unique low-density pitting damage is discovered and subsequently eliminated by optimizing the etching parameters. Meanwhile etching anisotropy also improves a lot, thus preventing the lateral etching of SSD. Using this proposed technique, SSD layer of fused silica is successfully removed with a surface roughness of 0.23 nm.

  12. Ultrasonic evaluation of creep damage of Cr-Mo-V steel by acoustic microscopy

    Institute of Scientific and Technical Information of China (English)

    WEI Tingcun

    2004-01-01

    The evaluation of creep damages of Cr-Mo-V steel used in the gas turbine of power plant has been carried out using the line-focus-beam (LFB) acoustic microscopy. The velocity of leaky surface acoustic wave (LSAW) propagated near the specimen surface was used for the quantitative evaluations, which was measured by LFB acoustic microscopy using the v(z) curve analysis method. It has been shown that with the increase of creep damage fraction of metal material the LSAW velocity decreases obviously, which suggests the possibility of nondestructive and quantitative evaluations of creep damages in metal materials by acoustic microscopy.

  13. A damage model for fracking

    OpenAIRE

    Norris, J. Quinn; Turcotte, Donald L.; John B. Rundle

    2015-01-01

    Injections of large volumes of water into tight shale reservoirs allows the extraction of oil and gas not previously accessible. This large volume "super" fracking induces damage that allows the oil and/or gas to flow to an extraction well. The purpose of this paper is to provide a model for understanding super fracking. We assume that water is injected from a small spherical cavity into a homogeneous elastic medium. The high pressure of the injected water generates hoop stresses that reactiv...

  14. Quantification of thermal damage in skin tissue

    Institute of Scientific and Technical Information of China (English)

    Xu Feng; Wen Ting; Lu Tianjian; Seffen Keith

    2008-01-01

    Skin thermal damage or skin burns are the most commonly encountered type of trauma in civilian and military communities. Besides, advances in laser, microwave and similar technologies have led to recent developments of thermal treatments for disease and damage involving skin tissue, where the objective is to induce thermal damage precisely within targeted tissue structures but without affecting the surrounding, healthy tissue. Further, extended pain sensation induced by thermal damage has also brought great problem for burn patients. Thus, it is of great importance to quantify the thermal damage in skin tissue. In this paper, the available models and experimental methods for quantification of thermal damage in skin tissue are discussed.

  15. Experiment and numerical simulation of welding induced damage: stainless steel 15-5PH

    International Nuclear Information System (INIS)

    The objective of this study is the prediction of damage and residual stresses induced by hot processing which leads to phase transformation in martensitic stainless steel. This study firstly concerns the modelling of the damage of material induced by a complex history of thermo-elastoplastic multiphase in heat-affected-zone (HAZ) of welding. In this work, a two-scale mode of elastoplastic damage multiphase was developed in the framework of thermodynamics of irreversible process. The constitutive equations are coupling with ductile damage, elasto-plasticity, phase transformation, and transformation plasticity. Besides, a damage equation was proposed based on the Lemaitre's damage model in the framework of continuum damage mechanics. The experiments of 15-5PH were implemented for the identification of phase transformation, transformation plasticity and damage models. Tensile tests of round specimens were used to identify the parameters of damage model as well as mechanical behaviours at various temperatures. Tests of flat notched specimen were designed to provide the validation of damage model and strain localization using three dimensional image correlation technologies. In addition, microscopic analysis was performed to provide microstructure characterization of 15-5PH and to discover the damage mechanism. Finally the numerical simulation was performed in the code CAST3M of CEA. On the one hand, numerical verification of the flat notched plates was implemented and compared with experimental results. On the other hand, we used the two-scale model including phase transformation, transformation plasticity and damage to simulate the level of residual stresses of a disk made of 15-5PH metal heated by laser. The internal variables, such as strain, stress, damage, were successfully traced in the simulation of two-scale model. The simulation results showed the transformation plasticity changes the level of residual stresses and should not be negligible; damage decreases

  16. Continuum damage and fracture mechanics

    CERN Document Server

    Öchsner, Andreas

    2016-01-01

    This textbook offers readers an introduction to damage and fracture mechanics, equipping them to grasp the basic ideas of the presented approaches to modeling in applied mechanics. In the first part, the book reviews and expands on the classical theory of elastic and elasto-plastic material behavior. A solid understanding of these two topics is the essential prerequisite to advancing to damage and fracture mechanics. Thus, the second part of this course provides an introduction to the treatment of damage and fractures in the context of applied mechanics. Wherever possible, the one-dimensional case is first introduced and then generalized in a following step. This departs somewhat from the more classical approach, where first the most general case is derived and then simplified to special cases. In general, the required mathematics background is kept to a minimum.   Tutorials are included at the end of each chapter, presenting the major steps for the solution and offering valuable tips and tricks. The supplem...

  17. Economic measurement of environment damages

    Energy Technology Data Exchange (ETDEWEB)

    Krawiec, F.

    1980-05-01

    The densities, energy consumption, and economic development of the increasing population exacerbate environmental degradation. Air and water pollution is a major environmental problem affecting life and health, outdoor recreation, household soiling, vegetation, materials, and production. The literature review indicated that numerous studies have assessed the physical and monetary damage to populations at risk from excessive concentrations of major air and water pollutants-sulfur dioxide, total suspended particulate matter, oxidants, and carbon monoxide in air; and nutrients, oil, pesticides, and toxic metals and others in water. The measurement of the damages was one of the most controversial issues in pollution abatement. The methods that have been used to estimate the societal value of pollution abatement are: (1) chain of effects, (2) market approaches, and (3) surveys. National gross damages of air pollution of $20.2 billion and of water pollution of $11.1 billion for 1973 are substantial. These best estimates, updated for the economic and demographic conditions, could provide acceptable control totals for estimating and predicting benefits and costs of abating air and water pollution emissions. The major issues to be resolved are: (1) lack of available noneconomic data, (2) theoretical and empirical difficulties of placing a value on human life and health and on benefits such as aesthetics, and (3) lack of available demographic and economic data.

  18. Advanced Mitigation Process (AMP) for Improving Laser Damage Threshold of Fused Silica Optics

    Science.gov (United States)

    Ye, Xin; Huang, Jin; Liu, Hongjie; Geng, Feng; Sun, Laixi; Jiang, Xiaodong; Wu, Weidong; Qiao, Liang; Zu, Xiaotao; Zheng, Wanguo

    2016-08-01

    The laser damage precursors in subsurface of fused silica (e.g. photosensitive impurities, scratches and redeposited silica compounds) were mitigated by mineral acid leaching and HF etching with multi-frequency ultrasonic agitation, respectively. The comparison of scratches morphology after static etching and high-frequency ultrasonic agitation etching was devoted in our case. And comparison of laser induce damage resistance of scratched and non-scratched fused silica surfaces after HF etching with high-frequency ultrasonic agitation were also investigated in this study. The global laser induce damage resistance was increased significantly after the laser damage precursors were mitigated in this case. The redeposition of reaction produce was avoided by involving multi-frequency ultrasonic and chemical leaching process. These methods made the increase of laser damage threshold more stable. In addition, there is no scratch related damage initiations found on the samples which were treated by Advanced Mitigation Process.

  19. Laser Induced Damage Studies in Borosilicate Glass Using nanosecond and sub nanosecond pulses

    CERN Document Server

    Rastogi, Vinay; Munda, D S

    2016-01-01

    The damage mechanism induced by laser pulse of different duration in borosilicate glass widely used for making confinement geometry targets which are important for laser driven shock multiplication and elongation of pressure pulse, is studied. We measured the front and rear surface damage threshold of borosilicate glass and their dependency on laser parameters. In this paper, we also study the thermal effects on the damage diameters, generated at the time of plasma formation. These induced damage width, geometries and microstructure changes are measured and analyzed with optical microscope, scanning electron microscope and Raman spectroscopy. The results show that at low energies symmetrical damages are found and these damage width increases nonlinearly with laser intensity. The emitted optical spectrum during the process of breakdown is also investigated and is used for the characterization of emitted plasma such as plasma temperature and free electron density. Optical emission lines from Si I at 500 nm, Si ...

  20. Improving laser damage resistance of 355 nm high-reflective coatings by co-evaporated interfaces.

    Science.gov (United States)

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

    2016-03-15

    355 nm high-reflective multilayer coatings with or without coevaporated interfaces (CEIs) were prepared by electron beam evaporation under the same deposition condition. Their transmission spectra, surface roughness, and mechanical stress properties were evaluated. Elemental composition analysis of the multilayer interfaces was performed using x-ray photoelectron spectroscopy, and laser-induced damage thresholds were obtained in both 1-on-1 and 300-on-1 testing modes. The coatings with CEIs reveal a lower mechanical stress and a higher laser damage resistance when irradiated with high laser fluence, and the corresponding damage modeling indicates that CEIs can significantly decrease defect density. The resulting damage morphologies show that CEI coatings can significantly suppress coating delamination and exhibit a "bulk-like" damage behavior, demonstrating better damage performance against high-power lasers. PMID:26977682

  1. Advanced Mitigation Process (AMP) for Improving Laser Damage Threshold of Fused Silica Optics.

    Science.gov (United States)

    Ye, Xin; Huang, Jin; Liu, Hongjie; Geng, Feng; Sun, Laixi; Jiang, Xiaodong; Wu, Weidong; Qiao, Liang; Zu, Xiaotao; Zheng, Wanguo

    2016-01-01

    The laser damage precursors in subsurface of fused silica (e.g. photosensitive impurities, scratches and redeposited silica compounds) were mitigated by mineral acid leaching and HF etching with multi-frequency ultrasonic agitation, respectively. The comparison of scratches morphology after static etching and high-frequency ultrasonic agitation etching was devoted in our case. And comparison of laser induce damage resistance of scratched and non-scratched fused silica surfaces after HF etching with high-frequency ultrasonic agitation were also investigated in this study. The global laser induce damage resistance was increased significantly after the laser damage precursors were mitigated in this case. The redeposition of reaction produce was avoided by involving multi-frequency ultrasonic and chemical leaching process. These methods made the increase of laser damage threshold more stable. In addition, there is no scratch related damage initiations found on the samples which were treated by Advanced Mitigation Process. PMID:27484188

  2. Tissue damage negatively regulates LPS-induced macrophage necroptosis.

    Science.gov (United States)

    Li, Z; Scott, M J; Fan, E K; Li, Y; Liu, J; Xiao, G; Li, S; Billiar, T R; Wilson, M A; Jiang, Y; Fan, J

    2016-09-01

    Infection is a common clinical complication following tissue damage resulting from surgery and severe trauma. Studies have suggested that cell pre-activation by antecedent trauma/tissue damage profoundly impacts the response of innate immune cells to a secondary infectious stimulus. Cell necroptosis, a form of regulated inflammatory cell death, is one of the mechanisms that control cell release of inflammatory mediators from important innate immune executive cells such as macrophages (Mφ), which critically regulate the progress of inflammation. In this study, we investigated the mechanism and role of trauma/tissue damage in the regulation of LPS-induced Mφ necroptosis using a mouse model simulating long-bone fracture. We demonstrate that LPS acting through Toll-like receptor (TLR) 4 promotes Mφ necroptosis. However, necroptosis is ameliorated by high-mobility group box 1 (HMGB1) release from damaged tissue. We show that HMGB1 acting through cell surface receptor for advanced glycation end products (RAGE) upregulates caveolin-1 expression, which in turn induces caveolae-mediated TLR4 internalization and desensitization to decrease Mφ necroptosis. We further show that RAGE-MyD88 activation of Cdc42 and subsequent activation of transcription factor Sp1 serves as a mechanism underlying caveolin-1 transcriptional upregulation. These results reveal a previous unidentified protective role of damage-associated molecular pattern (DAMP) molecules in restricting inflammation in response to exogenous pathogen-associated molecular pattern molecules. PMID:26943325

  3. Damage Detection and Localization from Dense Network of Strain Sensors

    Directory of Open Access Journals (Sweden)

    Simon Laflamme

    2016-01-01

    Full Text Available Structural health monitoring of large systems is a complex engineering task due to important practical issues. When dealing with large structures, damage diagnosis, localization, and prognosis necessitate a large number of sensors, which is a nontrivial task due to the lack of scalability of traditional sensing technologies. In order to address this challenge, the authors have recently proposed a novel sensing solution consisting of a low-cost soft elastomeric capacitor that transduces surface strains into measurable changes in capacitance. This paper demonstrates the potential of this technology for damage detection, localization, and prognosis when utilized in dense network configurations over large surfaces. A wind turbine blade is adopted as a case study, and numerical simulations demonstrate the effectiveness of a data-driven algorithm relying on distributed strain data in evidencing the presence and location of damage, and sequentially ranking its severity. Numerical results further show that the soft elastomeric capacitor may outperform traditional strain sensors in damage identification as it provides additive strain measurements without any preferential direction. Finally, simulation with reconstruction of measurements from missing or malfunctioning sensors using the concepts of virtual sensors and Kriging demonstrates the robustness of the proposed condition assessment methodology for sparser or malfunctioning grids.

  4. Subsurface Damage in Scratch Testing of Potassium Dihydrogen Phosphate Crystal

    Institute of Scientific and Technical Information of China (English)

    WANG Ben; WU Dongjiang; GAO Hang; KANG Renke; GUO Dongming

    2009-01-01

    Potassium dihydrogen phosphate (KDP) is an important electro-optic crystal, often used for frequency conversion and Pockels cells in large aperture laser systems. To investigate the influence of anisotropy to the depth of subsurface damage and the profiles of cracks in subsurface of KDP crystal, an experimental study was made to obtain the form of subsurface damage produced by scratches on KDP crystal in [100], [120] and [110] crystal directions on (001) crystal plane. The results indicated that there were great differences between depth and crack shape in different directions. For many slip planes in KDP, the plastic deformation and cracks generated under pressure in the subsurfacewerecomplex. Fluctuations of subsurface damage depth at transition point were attributed to the deformation of the surface which consumed more energy when the surface deformation changed from the mixed region of brittle and plastic to the complete brittle region along the scratch. Also, the process of subsurface damage from shallow to deep, from dislocation to big crack in KDP crystal with the increase of radial force and etch pit on different crystal plane were obtained. Because crystallographic orientation and processing orientation was different, etching pits on (100) crystal plane were quadrilateral while on (110) plane and (120) plane were trapezoidal and triangular, respectively.

  5. Investigation of cutting-induced damage in CMC bend bars

    Directory of Open Access Journals (Sweden)

    Neubrand A.

    2015-01-01

    Full Text Available Ceramic matrix composites (“CMC” with a strong fibre-matrix interface can be made damage-tolerant by introducing a highly porous matrix. Such composites typically have only a low interlaminar shear strength, which can potentially promote damage when preparing specimens or components by cutting. In order to investigate the damage induced by different cutting methods, waterjet cutting with and without abrasives, laser-cutting, wire eroding and cutoff grinding were used to cut plates of two different CMCs with a matrix porosity up to 35 vol.-%. For each combination of cutting method and composite, the flexural and interlaminar shear strength of the resulting specimens was determined. Additionally, the integrity of the regions near the cut surfaces was investigated by high-resolution x-ray computer tomography. It could be shown that the geometrical quality of the cut is strongly affected by the cutting method employed. Laser cut and waterjet cut specimens showed damage and delaminations near the cut surface leading to a reduced interlaminar shear strength of short bend bars in extreme cases.

  6. Radiation damage effects in zircon

    Science.gov (United States)

    Trachenko, Kostya; Dove, Martin; Salje, Ekhard

    2002-03-01

    Zircon, ZrSiO_4, is important for geology and geochronology, and has been proposed as a host material to immobilize highly radioactive materials from dismantled weapons and nuclear waste from power stations [1]. In these applications zircon is exposed to alpha-irradiation. Computer simulations have started to be employed to simulate radiation damage in zircon [2], but the origin and microscopic mechanisms of the most important structural changes in zircon - unit cell expansion and large macroscopic swelling at higher doses, strong shear deformation of the crystalline lattice, and polymerization of SiOn units [3], remain unknown. Here, we perform the molecular dynamics simulation of highly energetic recoils in zircon. Basing on the simulation results, we propose the simple picture of the density change in the damaged region that consists of the depleted and densified matter. We find that the experimentally observed structural changes originate from the interaction of the damaged region with the surrounding crystalline lattice: the shear of the lattice around the damaged region causes shear deformation and expansion of the unit cells. The polymers of connected SiOn polyhedra are most commonly present in the densified shell at the periphery of the damaged region. [1] R C Ewing et al, J. Mater. Res. 10, 243 (1995); W J Weber et al, B E Burakov et al, in Scientific Basis for Nuclear Waste Management XIX, 25-32 and 33-40 (Plenum, New York, 1996); R C Ewing, et al in Crystalline Ceramics: Waste Forms for the Disposal of Weapons Plutonium, NATO Workshop Proceedings 65 (Academic Publishers, Dordrecht, The Netherlands, 1996). [2] B Park et al, Phys. Rev. B, 64, 174108 (1-16) (2001); J P Crocombette and D Ghaleb, J. Nucl. Mater., 295, 167 (2001); K Trachenko et al, J. Appl. Phys., 87, 7702 (2000); K Trachenko et al, J. Phys.: Cond. Matt., 13, 1947 (2001). [3] T Murakami et al, Am. Min., 76, 1510 (1991); H D Holland and D Gottfried, Acta Cryst. 8, 291 (1955).; W J Weber, J. Am

  7. Damage assessment of compression loaded debond damaged sandwich panels

    DEFF Research Database (Denmark)

    Moslemian, Ramin; Berggreen, Christian; Quispitupa, Amilcar;

    2010-01-01

    Sandwich composites with face sheets of fiber-reinforced plastics (FRP) and cores of polymer foam offer a lightweight construction that is well suited to wind turbine blades, naval and other vessels for high-speed operation or where payload considerations require that the structural weight...... be minimized. Some of these applications involve the use of highly optimized sandwich solutions. Studies are under way to establish how the structural performance is influenced by the presence of production defects or in-service damage. This paper deals with the failure of compression loaded sandwich panels...

  8. Strain localization and damage development in 2060 alloy during bending

    Institute of Scientific and Technical Information of China (English)

    Xiao Jin; Bao-qin Fu; Cheng-lu Zhang; Wei Liu

    2015-01-01

    The microstructure evolution and damage development of the third-generation Al–Li alloy 2060 (T8) were studied using in situ bending tests. Specimens were loaded with a series of punches of different radii, and the microstructure evolution was studied by scanning electron microscopy, electron backscatter diffraction, and digital image correlation (DIC) methods. The evolution of the microscopic fracture strain distribution and microstructure in 2060 alloy during bending was characterized, where the dispersion distribution of precipitates was recorded by backscattered electron imaging and later inputted into a DIC system for strain calculations. The experimental results showed that strain localization in the free surface of bent specimens induced damage to the microstructure. The region of crack initiation lies on the free surface with maximum strain, and the shear crack propagates along the macro-shear band in the early stages of bending. Crack propagation in the later stages was interpreted on the basis of the conventional mechanism of ductile fracture.

  9. Database of average-power damage thresholds at 1064 nm

    International Nuclear Information System (INIS)

    We have completed a database of average-power, laser-induced, damage thresholds at 1064 nm on a variety of materials. Measurements were made with a newly constructed laser to provide design input for moderate and high average-power laser projects. The measurements were conducted with 16-ns pulses at pulse-repetition frequencies ranging from 6 to 120 Hz. Samples were typically irradiated for time ranging from a fraction of a second up to 5 minutes (36,000 shots). We tested seven categories of samples which included antireflective coatings, high reflectors, polarizers, single and multiple layers of the same material, bare and overcoated metal surfaces, bare polished surfaces, and bulk materials. The measured damage threshold ranged from 2 for some metals to > 46 J/cm2 for a bare polished glass substrate. 4 refs., 7 figs., 1 tab

  10. Damage behaviors of fiber Bragg grating sensor in fabrication

    Science.gov (United States)

    Tang, Liqun; Sang, Dengfeng; Chen, Jinming; Yang, Bao; Liu, Yiping

    2008-11-01

    It is has been noted that for fiber Bragg grating sensor (FBGS), the tensile strengths of fiber Bragg grating sensors (FBGSs) were decreased after the gratings were written, which may reduce the sensor's measurement range obviously. In this paper, we focused on the damage behaviours of FBGS after fabrication experimentally. Firstly, the tensile tests were carried to measure the tensile strengths of naked optical fiber, decoated optical fiber and optical fiber with Bragg gratings to learn deduction of the tensile strength of optical fiber in the cases respectively. Further, the microscope photography was used to observe the surfaces of optical fiber with or without exposure of excimer laser. The main conclusion is that the UV pulse is the main contribution to reduce the strength remarkably, and the mechanical decoating method also can induce the surface damage on the optical fiber.

  11. Case Study of Local Damage Indicators for a 2-Bay, 6-Storey RC-Frame subject to Earthquakes

    DEFF Research Database (Denmark)

    Skjærbæk, P. S.; Nielsen, Søren R. K.; Kirkegaard, Poul Henning;

    1997-01-01

    A simulation study of a 2-bay, 6storey model test RC-frame(scale 1:5) subject to earthquakes is considered in this paper. Based on measured (simulated) storey accelerations and ground surface accelerations several indices for the storey damage, including interstorey drift, flexural damage ratios......, normalized cumulative dissipated energy, Park and Ang's indicator, a low-cycle fatigue damage index and a recently proposed local softening damage index estimated from time-varying eigenfrequencies are used to evaluate the damage state of the structure after the earthquake. Storey displacements are obtained...

  12. Case Study of Local Damage Indicators for a 2-Bay, 6-Storey RC-Frame subject to Earthquakes

    DEFF Research Database (Denmark)

    Skjærbæk, P. S.; Nielsen, Søren R. K.; Kirkegaard, Poul Henning;

    A simulation study of a 2-bay, 6storey model test RC-frame(scale 1:5) subject to earthquakes is considered in this paper. Based on measured (simulated) storey accelerations and ground surface accelerations several indices for the storey damage, including interstorey drift, flexural damage ratios......, normalized cumulative dissipated energy, Park and Ang's indicator, a low-cycle fatigue damage index and a recently proposed local softening damage index estimated from time-varying eigenfrequencies are used to evaluate the damage state of the structure after the earthquake. Storey displacements are obtained...

  13. How Acid Reflux Disease Damages Teeth

    Science.gov (United States)

    ... more Seniors' Oral Health How to Keep Your Teeth for a Lifetime Tooth loss is simply the ... your desktop! more... How Acid Reflux Disease Damages Teeth Article Chapters How Acid Reflux Disease Damages Teeth ...

  14. DNA Damage and Repair in Vascular Disease.

    Science.gov (United States)

    Uryga, Anna; Gray, Kelly; Bennett, Martin

    2016-01-01

    DNA damage affecting both genomic and mitochondrial DNA is present in a variety of both inherited and acquired vascular diseases. Multiple cell types show persistent DNA damage and a range of lesions. In turn, DNA damage activates a variety of DNA repair mechanisms, many of which are activated in vascular disease. Such DNA repair mechanisms either stall the cell cycle to allow repair to occur or trigger apoptosis or cell senescence to prevent propagation of damaged DNA. Recent evidence has indicated that DNA damage occurs early, is progressive, and is sufficient to impair function of cells composing the vascular wall. The consequences of persistent genomic and mitochondrial DNA damage, including inflammation, cell senescence, and apoptosis, are present in vascular disease. DNA damage can thus directly cause vascular disease, opening up new possibilities for both prevention and treatment. We review the evidence for and the causes, types, and consequences of DNA damage in vascular disease. PMID:26442438

  15. Galvanic effects on cavitation damage for 1Cr13 stainless steel

    Institute of Scientific and Technical Information of China (English)

    Dongbai Sun; Xia Bai; Hongying Yu; Huimin Meng; Huiqing Li

    2003-01-01

    Based on the electric-spark principle, a new kind of cavitation damage testing apparatus was designed, which could produce the bubble. Bubbles collapsed and acted on a small surface area of the alloy surface, so an intensive electrochemical inhomoge nous state would be induced and lead to the existence of surface galvanic effect on the alloy. The galvanic effect of 1Cr13 SS during cavitation damage has been quantitatively investigated in NaCl solution. The results show that intensive galvanic effect of 1Crl3 SS during cavitation damage appears the potential of the damaged area shifting negatively with the bubble collapse and simultaneously the galvanic current generates. The mass loss of alloy due to cavitation increases with the bubble quantity, and increases with the in creasing of Cl- content. And both the total mass loss and the mass loss due to galvanic corrosion increase linearly with the area ratio of cavitation damaged to undamaged area. Such surface galvanic effects speed up the dissolution rate of the alloy, which, in turn, accelerates the mechanical damage, and aggravates the mass loss of the alloy. It has been further confirmed that the mass loss due to the surface galvanic effect can be decreased by catholic protection.

  16. Procedural Issues Concerning Environmental Damage In Ecuador

    Directory of Open Access Journals (Sweden)

    René Bedón Garzón

    2013-01-01

    Full Text Available This paper aims to determine, through a deep analysis of different doctrines, the definition of environmental damage; it also seeks to determine the difference between damage to nature and the civil environmental damage, which is damage to individual interests or collective environmental event occasion. To this purpose, we intend to study certain procedural rules and case law concerning Ecuadorian environmental management, also in comparative law considers how countries like Chile, Spain and Argentina regulate compensation and repair environment.

  17. Quantification of thermal damage in skin tissue

    Institute of Scientific and Technical Information of China (English)

    徐峰; 文婷; 卢天健; Seffen; Keith

    2008-01-01

    Skin thermal damage or skin burns are the most commonly encountered type of trauma in civilian and military communities. Besides, advances in laser, microwave and similar technologies have led to recent developments of thermal treatments for disease and damage involving skin tissue, where the objective is to induce thermal damage precisely within targeted tissue structures but without affecting the surrounding, healthy tissue. Further, extended pain sensation induced by thermal damage has also brought great...

  18. Damage Caused by Wheeled Skidders on Cambisols of Central Europe

    OpenAIRE

    Allman, Michal; Ferenčík, Michal; Jankovský, Martin; Stanovský, Miroslav; Messingerová, Valéria

    2015-01-01

    Machine traffic and timber skidding significantly affect the soil surface and soil properties. The effects are mostly negative and result in soil erosion, worsening of soil properties and inhibition of the growth of roots and soil organisms. In this study, we evaluated forest soil damage caused by the HSM 805 HD wheeled skidder during timber skidding in selected forest stands in the School Forest Enterprise in Zvolen. We estimated the limits for operation of forest machines in the stands and ...

  19. 7 CFR 51.1010 - Damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Damage. 51.1010 Section 51.1010 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Persian (Tahiti) Limes Definitions § 51.1010 Damage. Damage means any defect which...

  20. 7 CFR 51.646 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.646 Section 51.646 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...) Definitions § 51.646 Serious damage. Serious damage means any specific defect described in § 51.652, Table...

  1. 7 CFR 51.1874 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.1874 Section 51.1874 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Fresh Tomatoes 1 Definitions § 51.1874 Serious damage. Serious damage means any...

  2. 7 CFR 51.708 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.708 Section 51.708 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... § 51.708 Serious damage. Serious damage means any specific defect described in § 51.713, Table IV;...

  3. 7 CFR 51.2129 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.2129 Section 51.2129 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Shelled Almonds Definitions § 51.2129 Serious damage. Serious damage means...

  4. 7 CFR 51.1222 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.1222 Section 51.1222 Agriculture... Standards for Grades of Peaches Definitions § 51.1222 Serious damage. “Serious damage” means any injury or... allowed for any one defect, shall be considered as serious damage: (a) Bacterial spot, when any cracks...

  5. 7 CFR 51.3210 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.3210 Section 51.3210 Agriculture... Standards for Grades of Bermuda-Granex-Grano Type Onions Definitions § 51.3210 Serious damage. Serious..., shall be considered as serious damage: (a) Seedstems when more than 1/2 inch in diameter; (b) Dry...

  6. 7 CFR 51.1561 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.1561 Section 51.1561 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Potatoes 1 Definitions § 51.1561 Serious damage. Serious damage means any defect,...

  7. 7 CFR 51.1358 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.1358 Section 51.1358 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Pears for Canning Definitions § 51.1358 Serious damage. Serious damage means any injury...

  8. 7 CFR 51.777 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.777 Section 51.777 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Florida Grapefruit Definitions § 51.777 Serious damage. Serious damage means...

  9. 7 CFR 51.1833 - Serious damage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.1833 Section 51.1833 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Florida Tangerines Definitions § 51.1833 Serious damage. Serious damage means...

  10. Subclinical organ damage and cardiovascular risk prediction

    DEFF Research Database (Denmark)

    Sehestedt, Thomas; Olsen, Michael H

    2010-01-01

    by measuring subclinical organ damage. We have (i) reviewed recent studies linking markers of subclinical organ damage in the heart, blood vessels and kidney to cardiovascular risk; (ii) discussed the evidence for improvement in cardiovascular risk prediction using markers of subclinical organ damage; (iii...

  11. The Research of Liquidated Damages in China

    Institute of Scientific and Technical Information of China (English)

    Xu; Ting

    2014-01-01

    <正>I.Liquidated damages provisions of Anglo-American countries distinguished from that in China Liquidated damages provisions in Anglo-American countries are different from penalty clauses.However,Chinese law does not recognise liquidated damages in the same way as in Anglo-

  12. Damage Diagnosis for High Temperature Coke-oven Chamber Walls

    Science.gov (United States)

    Sugiura, Masato; Sakaida, Michitaka; Fujikake, Yohichi; Irie, Keisuke

    Metallurgical coke is needed as reducing reagent and energy source in blast furnaces. Most of coke ovens in Japan have been working over 30 years and have become gradually decrepit. A coke oven consists of many coking chambers, and each chamber is 6 m high, 16 m long and 0.4m wide. Uneven damage at the chamber-wall surface such as brick erosion and carbon deposition disturbs production because the coke is pushed horizontally when discharged from the chamber. To diagnose the chamber wall which is constantly sustained at a high temperature, we have developed a water-cooling heat-resistance probe. Line scan cameras mounted in the probe obtain thermal images of the entire chamber-wall surfaces with high resolution. In addition, to measure topographical information of the wall, a laser light-section method combined with line-scan-camera imaging has been considered. It is emphasized that the diagnosis probe works under enormously severe conditions, such as at a temperature of over 1000°C and inside a width of only 0.4m. Clarifying the appearance of chamber-wall damages in operating aged coke ovens, we proposed the index relating unevenness of a chamber-wall surface to pushing load. The index is utilized for the guidance enabling effective repairs of damaged oven walls.

  13. Structural Health Monitoring for Impact Damage in Composite Structures.

    Energy Technology Data Exchange (ETDEWEB)

    Roach, Dennis P.; Raymond Bond (Purdue); Doug Adams (Purdue)

    2014-08-01

    Composite structures are increasing in prevalence throughout the aerospace, wind, defense, and transportation industries, but the many advantages of these materials come with unique challenges, particularly in inspecting and repairing these structures. Because composites of- ten undergo sub-surface damage mechanisms which compromise the structure without a clear visual indication, inspection of these components is critical to safely deploying composite re- placements to traditionally metallic structures. Impact damage to composites presents one of the most signi fi cant challenges because the area which is vulnerable to impact damage is generally large and sometimes very dif fi cult to access. This work seeks to further evolve iden- ti fi cation technology by developing a system which can detect the impact load location and magnitude in real time, while giving an assessment of the con fi dence in that estimate. Fur- thermore, we identify ways by which impact damage could be more effectively identi fi ed by leveraging impact load identi fi cation information to better characterize damage. The impact load identi fi cation algorithm was applied to a commercial scale wind turbine blade, and results show the capability to detect impact magnitude and location using a single accelerometer, re- gardless of sensor location. A technique for better evaluating the uncertainty of the impact estimates was developed by quantifying how well the impact force estimate meets the assump- tions underlying the force estimation technique. This uncertainty quanti fi cation technique was found to reduce the 95% con fi dence interval by more than a factor of two for impact force estimates showing the least uncertainty, and widening the 95% con fi dence interval by a fac- tor of two for the most uncertain force estimates, avoiding the possibility of understating the uncertainty associated with these estimates. Linear vibration based damage detection tech- niques were investigated in the

  14. Radiation damage of structural materials

    CERN Document Server

    Koutsky, Jaroslav

    1994-01-01

    Maintaining the integrity of nuclear power plants is critical in the prevention or control of severe accidents. This monograph deals with both basic groups of structural materials used in the design of light-water nuclear reactors, making the primary safety barriers of NPPs. Emphasis is placed on materials used in VVER-type nuclear reactors: Cr-Mo-V and Cr-Ni-Mo-V steel for RPV and Zr-Nb alloys for fuel element cladding. The book is divided into 7 main chapters, with the exception of the opening one and the chapter providing a phenomenological background for the subject of radiation damage. Ch

  15. Origin of plate tectonics: Grain-damage, inheritance and hysteresis

    Science.gov (United States)

    Bercovici, D.; Ricard, Y. R.

    2015-12-01

    The emergence of plate tectonics is enigmatic because of the lack of observations in the early Archean as well as the challenge of understanding how plates form. The damage theory of lithospheric weakening by grain-reduction provides a physical framework for plate generation. This model builds on grain-scale physics to describe planetary-scale processes, and is consistent with lab and field observations of polycrystalline rocks and lithospheric mylonites. Grain-damage accounts for the evolution of damage and healing by grain growth, hence predicts plate boundary formation and longevity, and how they depend on surface conditions. The establishment of global plate tectonics likely started between >4Ga and 2.7Ga, and may have taken over a billion years to develop. Under Earth-like conditions, grain-damage combined with intermittent Archean protosubduction produces persistent weak zones that accumulate into well developed plates by 3Ga. However, Venus' hotter surface promotes healing, suppresses damage and inhibits weak zone accumulation, which suggests why plate tectonics failed to spread on our sister planet. New work posits that interface damage is possibly suppressed at moderate grain-size; this induces a hysteresis loop wherein three equilibrium deformation branches coexist. These branches include a stable large-grain, weakly-deforming state in dislocation creep, a stable small-grain rapidly-deforming state in diffusion creep analogous to mylonites, and an unstable intermediate-grain state. At the right conditions, a lithosphere can acquire two stable deformation states characteristic of plate tectonics; i.e., both slowly deforming plate interiors and rapidly deforming plate boundaries can co-exist. Earth currently sits inside the hysteresis loop and can have coexisting deformation states, while Venus sits at the end of the loop where only the weakly deforming branch dominates. The hot post-Hadean Earth might have had peak deformation only on the weakly

  16. Quantitative analysis of energetics of DNA damage

    Energy Technology Data Exchange (ETDEWEB)

    Nikjoo, H.; Goorley, T.; Fulford, J.; Takakura, K.; Ito, T

    2002-07-01

    Application of Monte Carlo track structure has been very successful in the modelling and quantification of DNA damage, clustered-damage and spectrum of DNA damage for energetic electrons and ions. However, there are paradoxical axioms in quantitative assessment of the energetics of DNA damage at very low electron energy and in the vacuum UV region. This paper, after a brief review of the parameters used in modelling of DNA damage, presents an analysis of experimental data of strand breaks in aqueous solution in the vacuum UV, the region to which little attention has been paid in spite of its fundamental importance in providing reaction parameters for radiation actions. (author)

  17. Capacitance-based damage detection sensing for aerospace structural composites

    Science.gov (United States)

    Bahrami, P.; Yamamoto, N.; Chen, Y.; Manohara, H.

    2014-04-01

    Damage detection technology needs improvement for aerospace engineering application because detection within complex composite structures is difficult yet critical to avoid catastrophic failure. Damage detection is challenging in aerospace structures because not all the damage detection technology can cover the various defect types (delamination, fiber fracture, matrix crack etc.), or conditions (visibility, crack length size, etc.). These defect states are expected to become even more complex with future introduction of novel composites including nano-/microparticle reinforcement. Currently, non-destructive evaluation (NDE) methods with X-ray, ultrasound, or eddy current have good resolutions (analysis currently requires excessive wiring and complex signal analysis. Here, we present a capacitance sensor-based, structural defect detection technology with improved sensing capability. Thin dielectric polymer layer is integrated as part of the structure; the defect in the structure directly alters the sensing layer's capacitance, allowing full-coverage sensing capability independent of defect size, orientation or location. In this work, capacitance-based sensing capability was experimentally demonstrated with a 2D sensing layer consisting of a dielectric layer sandwiched by electrodes. These sensing layers were applied on substrate surfaces. Surface indentation damage (~1mm diameter) and its location were detected through measured capacitance changes: 1 to 250 % depending on the substrates. The damage detection sensors are light weight, and they can be conformably coated and can be part of the composite structure. Therefore it is suitable for aerospace structures such as cryogenic tanks and rocket fairings for example. The sensors can also be operating in space and harsh environment such as high temperature and vacuum.

  18. Irradiation damage in lithium ceramics

    International Nuclear Information System (INIS)

    The irradiation response of two candidate tritium-breeding materials, LiAlO2 and Li2ZrO3, was investigated using electron irradiation to produce atomic displacements, and EPR and transmission electron microscopy (TEM) to detect damage responses. In a first set of experiments, single crystals and sintered polycrystals of γ-LiAlO2 were irradiated with 2.5 MeV electrons at a temperature of 20 K. EPR measurements made at 4 K on samples kept at 77 K after electron irradiation confirm that paramagnetic defects are created during irradiation, and that most of these defects disappear at about 100 K. TEM observations at room temperature indicate, however, that annealing of these defects does not result in visible defect aggregates. In a second set of experiments, sintered polycrystalline LiAlO2 and Li2ZrO3 samples were thinned to electron transparency and heavily irradiated in situ with 200 keV electrons. In LiAlO2, laths of LiAl5O8 grew intragranularly under irradiation. Li2ZrO3 showed little or no aggregate damage after extensive irradiation near room temperature. (orig.)

  19. Malnutrition, liver damage, and cancer.

    Science.gov (United States)

    Grasso, P

    1981-01-01

    There is no clear indication that malnutrition, per se, is a principal cause of cancer in man, but the prevalence of liver cancer in areas where malnutrition exists supports this hypothesis. Liver damage and liver cancer have been induced in laboratory rats by diets consisting of peanut meal and proteins deficient in some essential amino acids. However, liver damage, but not cancer, was produced when the diets contained no peanut meal but consisted of a mixture of amino acids deficient in methionine and cysteine, so that it is possible that aflatoxin, a contaminant of peanut meal, may have been responsible for the malignancies seen in the earlier experiments. Liver cancer developes in a high proportion of mice allowed to feed ad libitum or given a diet containing a high proportion of fat (groundnut oil) or protein (casein). Dietary restriction reduced the incidences of this cancer. This findings lends some support to current thinking that diet may be a factor in the development of cancer in man.

  20. [Liver damage caused by drugs].

    Science.gov (United States)

    Strohmeyer, G; Weik, C

    1999-05-01

    The liver has a central role in the metabolism of many drugs, since this organ is the main site of biotransformation of endo- and xenobiotics. Water-soluble drugs have a small volume of distribution and can be eliminated unchanged in the urine. By contrast, lipid-soluble drugs have a larger volume of distribution and require conversion to water-soluble metabolites for their elimination in urine or bile. The liver with its specific receptors, transporters and enzymes is responsible for the uptake, transformation and excretion of the lipophilic drugs. While most of the drugs are transformed into stable metabolites, other drugs form reactive, potentially toxic, metabolites producing liver cell damage. Liver injury caused by drugs may mimic almost any kind of liver disease. Clinical findings are gastrointestinal symptoms with nausea, vomiting and abdominal pain, cholestatic liver injury with jaundice and pruritus of severe inflammatory and cirrhotic liver damage with signs of liver failure, encephalopathy and cerebral edema. The morphological changes vary from hepatitis, cholestasis, fatty liver, granulomatous hepatitis, peri-/portal inflammation, to fibrosis with cirrhotic alterations and vascular lesions and tumors. The most commonly used drugs causing severe liver injury are discussed in detail. These are anabolics, oral contraceptives, antituberculous and antifungal agents, nonsteroidal anti-inflammatory drugs, ring substituted amphetamins ("designer drugs"), antiarrhythmics and antibiotics.

  1. Excitotoxic damage to white matter

    Science.gov (United States)

    Matute, Carlos; Alberdi, Elena; Domercq, María; Sánchez-Gómez, María-Victoria; Pérez-Samartín, Alberto; Rodríguez-Antigüedad, Alfredo; Pérez-Cerdá, Fernando

    2007-01-01

    Glutamate kills neurons by excitotoxicity, which is caused by sustained activation of glutamate receptors. In recent years, it has been shown that glutamate can also be toxic to white matter oligodendrocytes and to myelin by this mechanism. In particular, glutamate receptor-mediated injury to these cells can be triggered by activation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid, kainate and N-methyl-d-aspartate glutamate receptor types. Thus, these receptor classes, and the intermediaries of the signal cascades they activate, are potential targets for drug development to treat white matter damage in acute and chronic diseases. In addition, alterations of glutamate homeostasis in white matter can determine glutamate injury to oligodendrocytes and myelin. Astrocytes are responsible for most glutamate uptake in synaptic and non-synaptic areas and consequently are the major regulators of glutamate homeostasis. Activated microglia in turn may secrete cytokines and generate radical oxygen species, which impair glutamate uptake and reduce the expression of glutamate transporters. Finally, oligodendrocytes also contribute to glutamate homeostasis. This review aims at summarizing the current knowledge about the mechanisms leading to oligodendrocyte cell death and demyelination as a consequence of alterations in glutamate signalling, and their clinical relevance to disease. In addition, we show evidence that oligodendrocytes can also be killed by ATP acting at P2X receptors. A thorough understanding of how oligodendrocytes and myelin are damaged by excitotoxicity will generate knowledge that can lead to improved therapeutic strategies to protect white matter. PMID:17504270

  2. Cell damage seen from Chernobyl

    International Nuclear Information System (INIS)

    The 30 kilometer radius forbidden zone around the Chernobyl atomic plant serves as a sobering reminder of the world's worst nuclear accident. But for former Soviet biologists, it's also a unique natural laboratory. And one scientist, Nadejda Gulaya of Kiev's Pallaguine Institute of Biochemistry, has been doing studies that she claims offer surprising evidence of Chernobyl's after-effects. Prolonged exposure to radioactive fallout from the 1986 accident, she says, has caused damage to cell membranes in both animals and humans. For the past year, Gulaya has been comparing tissues from animals such as mink, pigs, and rodents inhabiting the Chernobyl area with those from other parts of Ukraine. Her conclusion: Exposure to radiation has, in many cases, caused alterations to membrane phospholipids. These changes, are similar to those that disrupt cellular metabolism following exposure to oxidizing free radicals. Gulaya also has preliminary data from human studies. She claims to have found similar alterations in the neurons of people who have died since being exposed to Chernobyl radiation. That leads her to speculate that the frequent psychiatric disorders may not just be from mental stress or radiophobia, but might reflect actual damage to the central nervous system

  3. Pulverization Texturein Fault Damage Zones: A result of Implosion Damage or Dynamic Compressive Stresses?

    Science.gov (United States)

    Rockwell, T. K.; Girty, G.; Whearty, J.; Mitchell, T. M.

    2015-12-01

    Micro-brecciation, or pulverization, is recognized as a fundamental component of the architecture and damage products of many large faults, although the precise mechanisms to produce this damage are debated, with both compressive and tensile mechanisms proposed. We characterized several sites along the San Jacinto fault, southern California, where the total depth of exhumation for the life history of the fault can be determined, to study the confining stresses required for pulverization. In basement rock near Anza, where exhumation is less than 100 m, granitic dikes injected into schist of the Burnt Valley Complex are pulverized out to several meters from the fault core, whereas the schist is brecciated at the macro-scale and contains narrow centimeter-thick seams of black cataclasite. Similar relationships are observed in Horse Canyon, which is exhumed about 400 m below a regional Tertiary erosion surface, where granitic dikes emplaced into schist are pulverized out to distances of several tens of meters from the fault core. These observations imply that very low confining stress is required for micro-brecciation in granitic rock. Unconsolidated sandstones (alluvial fan deposits) along the SJF in Rock House Canyon are undeformed where the deposits are exhumed by about 70 m, but show incipient pulverization (high-density, sub-grain cracking) at 120 m depth of exhumation. Cracks oriented perpendicular to the fault formed in individual quartz and feldspar grains out to a few meters from the fault core. These observations suggest that the confining stress required for onset of pulverization in unconsolidated deposits is on the order of 2-2.5 MPa. As the tensile strength of quartz is an order of magnitude higher than these confining stresses, the most likely mechanism that is producing this damage is dynamic compressive stresses during passage of the rupture front.

  4. Millennium-long damage to building materials in London.

    Science.gov (United States)

    Brimblecombe, Peter; Grossi, Carlota M

    2009-02-01

    Damage functions from a range of sources are used to estimate deterioration of carbonate stone, iron and copper, in addition to the rate of blackening of stone surfaces in London across the period 1100-2100 CE. Meteorological and pollution input is available for only a relatively short part of this span, so non-instrumental weather records and modelled pollution are utilised for historic values, while future climate is adapted from the HadCM3A2 model output and pollution assessed from likely regulatory trends. The results from the different damage functions compare reasonably well showing comparable changes in damage rates with time. A potential square-root dependence of change in deposition velocity of SO2 to limestone suggests a possible overestimate of damage when pollution is high. Deterioration is especially intense from the 1700s. It is difficult to be certain whether the corrosion of copper accelerated as early as this or it developed in the 20th century. Nevertheless all the functions predict a decline in copper corrosion from the end of the 20th century. A blackening function was developed to relate elemental carbon concentration and the colour of deposited particulate matter to blackening rate, which suggests that soiling was particularly rapid in the late 19th century. The increase and subsequent decrease in damage to building materials is interpreted in terms of a Kuznets curve. The centuries where pollution controlled damage to durable building material seems to be over. Weathering, in a changing climate may have the greatest impact in the future.

  5. Damage Assessment of Composite Structures Using Digital Image Correlation

    Science.gov (United States)

    Caminero, M. A.; Lopez-Pedrosa, M.; Pinna, C.; Soutis, C.

    2014-02-01

    The steady increase of Carbon-Fiber Reinforced Polymer (CFRP) Structures in modern aircraft will reach a new dimension with the entry into service of the Boeing 787 and Airbus 350. Replacement of damaged parts will not be a preferable solution due to the high level of integration and the large size of the components involved. Consequently the need to develop repair techniques and processes for composite components is readily apparent. Bonded patch repair technologies provide an alternative to mechanically fastened repairs with significantly higher performance, especially for relatively thin skins. Carefully designed adhesively bonded patches can lead to cost effective and highly efficient repairs in comparison with conventional riveted patch repairs that cut fibers and introduce highly strained regions. In this work, the assessment of the damage process taking place in notched (open-hole) specimens under uniaxial tensile loading was studied. Two-dimensional (2D) and three-dimensional (3D) Digital Image Correlation (DIC) techniques were employed to obtain full-field surface strain measurements in carbon-fiber/epoxy T700/M21 composite plates with different stacking sequences in the presence of an open circular hole. Penetrant enhanced X-ray radiographs were taken to identify damage location and extent after loading around the hole. DIC strain fields were compared to finite element predictions. In addition, DIC techniques were used to characterise damage and performance of adhesively bonded patch repairs in composite panels under tensile loading. This part of work relates to strength/stiffness restoration of damaged composite aircraft that becomes more important as composites are used more extensively in the construction of modern jet airliners. The behaviour of bonded patches under loading was monitored using DIC full-field strain measurements. Location and extent of damage identified by X-ray radiography correlates well with DIC strain results giving confidence to

  6. Description of Concrete Durability Damage Process

    Institute of Scientific and Technical Information of China (English)

    CHEN Yueshun; WEI Jun; ZHAO Xiaolong

    2006-01-01

    Based on the damage mechanics, the concrete damage grade of relative stable environment in measurable spatial is constructed in this paper, and the concrete damage evolving model and corresponding failure rule is constructed based on the damage grade fore-defined. Therefore, the concrete health status and the residual life-span can be assessed according to the measured damage grade. It is propitious to drive the development of concrete durability assessment and life-span forecast. Its feasibility of concrcte damage process description and health assessment is validated with the example in this paper, in which the damage state is described with the ultrasound velocity attenuation, and the freeze-thaw process is regarded as the concrete durability degradation influencing factor to reflect the concrete durability degradation process.

  7. Damage development in the adhesive zone and mortar of porous asphalt concrete

    NARCIS (Netherlands)

    Mo, L.T.

    2010-01-01

    This research is focused on damage development in the adhesive zone and the mortar of porous asphalt concrete. The motive of this research is the loss of stone from the pavement surface, the so-called ravelling of noise reducing surface wearing courses. Ravelling is the dominant defect of porous asp

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

    International Nuclear Information System (INIS)

    Silicon substrate damage caused by HBr/O2 plasma exposure was investigated by spectroscopic ellipsometry (SE), high-resolution Rutherford backscattering spectroscopy, and transmission electron microscopy. The damage caused by H2, Ar, and O2 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/O2 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.

  9. Evaluation of microstructure and creep damage in high-Cr ferritic steel welds

    Institute of Scientific and Technical Information of China (English)

    Masaaki TABUCHI; Hiromichi HONGO

    2011-01-01

    11Cr-0.4Mo-2W-CuVNb steel (ASME Gr.122) is used for boiler components in ultrasupercritical (USC) thermal power plants. The creep strength of high-Cr steel welds decreases due to the formation of Type Ⅳ creep damage in the heat-affected zone (HAZ) during long-term use at high temperatures. In the present study, the processes and mechanisms of Type Ⅳ creep damage were elucidated by investigating the long-term creep strength, microstructure and damage behavior of Gr.122 steel welds.Creep tests using thick welded joints were interrupted at several time steps, and the initiation, evolution and distribution of creep damage were measured. It was found that the formation and growth of creep damage was suppressed during the steadystate stage; creep voids formed at 0.5 of life, and coalesced to form a crack after 0.9of life. Type Ⅳ creep damage was mostly observed in the area about 30% below the surface of the plate. Differences in creep damage behavior between Gr.122 and Gr.91 steel welds were examined. Experimental creep damage distribution was compared with computed versions using the finite element method and damage mechanics.

  10. Damage Resistant Optical Glasses for High Power Lasers: A Continuing Glass Science and Technology Challenge

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J H

    2002-08-28

    A major challenge in the development of optical glasses for high-power lasers is reducing or eliminating laser-induced damage to the interior (bulk) and the polished surface of the glass. Bulk laser damage in glass generally originates from inclusions. With the development of novel glass melting and forming processes it is now possible to make both fused silica and a suit of meta-phosphate laser glasses in large sizes ({approx}>0.5-lm diameter), free of inclusions and with high optical homogeneity ({approx} 10{sup -6}). Considerable attention also has been focused on improving the laser damage resistance to polished optical glass surfaces. Studies have shown that laser-induced damage to surfaces grows exponentially with the number of shots when illuminated with nano-second pulses at 351-nm above a given fluence threshold. A new approach for reducing and eliminating laser-induced surface damage relies on a series of post-polishing treatment steps. This damage improvement method is briefly reviewed.

  11. Legal protection against nuclear damage

    International Nuclear Information System (INIS)

    The IAEA Director General appointed an international Panel of Experts to go into the question of Civil Liability and State Responsibility for Nuclear Hazards. The Panel had before it certain basic postulates formulated after a preliminary and tentative consideration of the subject. From the viewpoint of the public, the first postulate is, of course, that the use of nuclear energy be regulated by adequate licensing and control mechanisms so as to prevent any accidents. To the extent, however, that nuclear damage cannot be prevented, there must be liability on the part of the enterprise which caused the damage and, where damage exceeds its liability or its financial resources there should be some assurance of compensation by the State. This should be so not only within the borders of one State, but especially also on an international basis. Security should be required for the possible liability of the enterprises connected with a nuclear incident. Litigation with respect to liability should be concentrated in the most convenient tribunal and be governed by a single clearly defined law. The methods of distribution should meet general standards of equity and be as expeditious as possible. Emergency measures, especially evacuation, first aid and decontamination, should be organized and financed without delay. At the same time, the liability of an enterprise should not exceed its reasonable financial capabilities. This means that a ceiling should be imposed upon the amount of third party liability to which an enterprise could be held. And the liability should generally be such as can be covered by adequate financial security. Uniformity in the treatment of victims of nuclear incidents in all these fields is a desirable goal. Yet, if a rule adopted on an international level or suggested by uniform legislation were to be viable, it should adapt itself to the social, economic and legal order already existing in individual States. This may mean that in certain fields it

  12. Durable, Low-Surface-Energy Treatments

    Science.gov (United States)

    Willis, Paul B.; Mcelroy, Paul M.; Hickey, Gregory S.

    1992-01-01

    Chemical treatment for creation of durable, low-surface-energy coatings for glass, ceramics and other protonated surfaces easily applied, and creates very thin semipermanent film with extremely low surface tension. Exhibits excellent stability; surfaces retreated if coating becomes damaged or eroded. Uses include water-repellent surfaces, oil-repellent surfaces, antimigration barriers, corrosion barriers, mold-release agents, and self-cleaning surfaces. Film resists wetting by water, alcohols, hydrocarbon solvents, and silicone oil. Has moderate resistance to abrasion, such as rubbing with cloths, and compression molding to polymers and composite materials.

  13. Darlington NGS fuel damage investigation

    International Nuclear Information System (INIS)

    Darlington Unit 2 operated successfully from July to November 1990, but then a fuelling machine jammed, and the problem was soon traced to fuel debris. Initial inspections done with the CIGAR video camera, and subsequent metallurgical inspections at AECL, showed that vibration had produced fatigue cracking of some fuel end plates, and the damaged fuel had fretted one or two pressure tubes. The inspection and modelling programs showed that the cause of the trouble was resonant amplification of pressure pulsations produced by the primary heat transport system pumps. The trouble, which also affected the operation of Unit 1, has been cured by changing the number of vanes on each impeller from five to seven. Other possible solutions were considered

  14. Nanofoams Response to Radiation Damage

    International Nuclear Information System (INIS)

    Conclusions of this presentation are: (1) np-Au foams were successfully synthesized by de-alloying process; (2) np-Au foams remain porous structure after Ne ion irradiation to 1 dpa; (3) SFTs were observed in irradiated np-Au foams with highest and intermediate flux, while no SFTs were observed with lowest flux; (4) SFTs were observed in irradiated np-Au foams at RT, whereas no SFTs were observed at LNT irradiation; (5) The diffusivity of vacancies in Au at RT is high enough so that the vacancies have enough time to agglomerate and thus collapse. As a result, SFTs were formed; (6) The high flux created much more damage/time, vacancies don't have enough time to diffuse or recombine. As a result, SFTs were formed.

  15. Nanofoams Response to Radiation Damage

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Engang [Los Alamos National Laboratory; Serrano De Caro, Magdalena [Los Alamos National Laboratory; Wang, Yongqiang [Los Alamos National Laboratory; Nastasi, Michael [Nebraska Center for Energy Sciences Research, University of Nebraska-Lincoln, NE 68508; Zepeda-Ruiz, Luis [PLS, Lawrence Livermore National Laboratory, Livermore, CA 94551; Bringa, Eduardo M. [CONICET and Inst. Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza, 5500 Argentina; Baldwin, Jon K. [Los Alamos National Laboratory; Caro, Jose A. [Los Alamos National Laboratory

    2012-07-30

    Conclusions of this presentation are: (1) np-Au foams were successfully synthesized by de-alloying process; (2) np-Au foams remain porous structure after Ne ion irradiation to 1 dpa; (3) SFTs were observed in irradiated np-Au foams with highest and intermediate flux, while no SFTs were observed with lowest flux; (4) SFTs were observed in irradiated np-Au foams at RT, whereas no SFTs were observed at LNT irradiation; (5) The diffusivity of vacancies in Au at RT is high enough so that the vacancies have enough time to agglomerate and thus collapse. As a result, SFTs were formed; (6) The high flux created much more damage/time, vacancies don't have enough time to diffuse or recombine. As a result, SFTs were formed.

  16. Apophyseal damage in adolescent athlete

    International Nuclear Information System (INIS)

    The increasing demands on the adolescent athlete in high perfomance sports puts high biomechanical stress on the growing structures of the active and passive locomotor system. The ''growing factor'' itself increases stretching forces on tendon insertions, which are often overloaded when a physical demanding sport is performed additionally. The apophysis is an ossification nucleus near the tendon insertion, which appears before the growing age resumes and these apophysis finally fuses with the adjacent bone. The tensile forces from vigorous sports activity leads to a chronic or acute avulsion of the ossifying tendon insertion. The radiological appearance of this apophyseal damage with ossification and osteolytic processes is sometimes difficult with respect to differential diagnoses. Apophyseal impairment is associated with pain, tenderness to palpation and decreased muscle function. If it is not diagnosed and treated properly it can lead to end of career in many adolescent athletes. (orig.)

  17. Drilling Damage in Composite Material

    Directory of Open Access Journals (Sweden)

    Luís Miguel P. Durão

    2014-05-01

    Full Text Available The characteristics of carbon fibre reinforced laminates have widened their use from aerospace to domestic appliances, and new possibilities for their usage emerge almost daily. In many of the possible applications, the laminates need to be drilled for assembly purposes. It is known that a drilling process that reduces the drill thrust force can decrease the risk of delamination. In this work, damage assessment methods based on data extracted from radiographic images are compared and correlated with mechanical test results—bearing test and delamination onset test—and analytical models. The results demonstrate the importance of an adequate selection of drilling tools and machining parameters to extend the life cycle of these laminates as a consequence of enhanced reliability.

  18. Radiation damage in silicon detectors

    CERN Document Server

    Bruzzi, Mara

    2000-01-01

    This work presents an overview of the most important mechanisms of radiation damage in silicon detectors to be used for high energy experiments in LHC. The changes in the shallow concentration have been studied by Thermally Stimulated Currents (TSC) after proton and neutron irradiation with fluences up to 1015 cm-2 to investigate the role of thermal donors and the donor-removal effect in standard and oxygen enriched silicon with different resistivities. Deep defects in irradiated silicon have been analysed by Deep Level Transient Spectroscopy (DLTS) and Photo Induced Current Transient Spectroscopy (P1CTS) in the same materials. The radiation-induced microscopic disorder has been related with the carrier transport properties of irradiated silicon measured by Hall effect, by capacitance and current vs. voltage characteristics and with charge collection efficiency. The dependence of the irradiated silicon detectors performances on crystal orientation, on incident particle type and on the starting concentration o...

  19. Repair of DNA damage induced by ultraviolet radiation

    International Nuclear Information System (INIS)

    Studies documenting the depletion of the ozone layer and the resulting increases in UV-B radiation (280-320 nm) at the Earth's surface have served to focus attention on the biological effects of UV light. One obvious target for UVB- induced damage is DNA. Although a11 biological tissues are rich in UV-absorbing agents (largely nucleic acids and proteins) and plants produce additional UV-absorbing pigments, no DNA in superficial tissue can completely avoid UV exposure. Plants, like a11 living organisms, must have some capacity for the repair of UV-induced DNA damage. Because plants are unique in the obligatory nature of their exposure to UV, it is also conceivable that they may have evolved particularly efficient mechanisms for the elimination of UV-induced DNA damage. This review will summarize what we know about DNA repair mechanisms in higher plants. Readers interested in broader aspects of UV-induced damage and UV filters are directed to recent reviews (Middleton and Teramura, 1994; Strid et al., 1994; Fiscus and Booker, 1995). Our knowledge of DNA repair mechanisms in plants lags far behind our understanding of these pathways in animals, and a significant number of questions concerning the basic phenomenology of DNA repair in plants remain to be addressed

  20. Terrorism and nuclear damage coverage

    International Nuclear Information System (INIS)

    This paper deals with nuclear terrorism and the manner in which nuclear operators can insure themselves against it, based on the international nuclear liability conventions. It concludes that terrorism is currently not covered under the treaty exoneration provisions on 'war-like events' based on an analysis of the concept on 'terrorism' and travaux preparatoires. Consequently, operators remain liable for nuclear damage resulting from terrorist acts, for which mandatory insurance is applicable. Since nuclear insurance industry looks at excluding such insurance coverage from their policies in the near future, this article aims to suggest alternative means for insurance, in order to ensure adequate compensation for innocent victims. The September 11, 2001 attacks at the World Trade Center in New York City and the Pentagon in Washington, DC resulted in the largest loss in the history of insurance, inevitably leading to concerns about nuclear damage coverage, should future such assaults target a nuclear power plant or other nuclear installation. Since the attacks, some insurers have signalled their intentions to exclude coverage for terrorism from their nuclear liability and property insurance policies. Other insurers are maintaining coverage for terrorism, but are establishing aggregate limits or sublimits and are increasing premiums. Additional changes by insurers are likely to occur. Highlighted by the September 11th events, and most recently by those in Madrid on 11 March 2004, are questions about how to define acts of terrorism and the extent to which such are covered under the international nuclear liability conventions and various domestic nuclear liability laws. Of particular concern to insurers is the possibility of coordinated simultaneous attacks on multiple nuclear facilities. This paper provides a survey of the issues, and recommendations for future clarifications and coverage options.(author)

  1. Radiation damage to DNA constituents

    International Nuclear Information System (INIS)

    The molecular changes of the DNA molecule, in various systems exposed to inoizing radiation, have been the subject of a great number of studies. In the present work electron spin resonance spectroscopy (ESR) has been applied to irradiated crystalline systems, in particular single crystals of DNA subunits and their derivatives. The main conclusions about the molecular damage are based on this technique in combination with molecular orbital calculations. It should be emphasized that the ESR technique is restricted to damage containing unpaired electrons. These unstable intermediates called free radicals seem, however, to be involved in all molecular models describing the action of radiation on DNA. One of the premises for a detailed theory of the radiation induced reactions at the physico-chemical level seems to involve exact knowledge of the induced free radicals as well as the modes of their formation and fate. For DNA, as such, it is hardly possible to arrive at such a level of knowledge since the molecular complexity prevents selective studies of the many different radiation induced products. One possible approach is to study the free radicals formed in the constituents of DNA. In the present work three lines of approach should be mentioned. The first is based on the observation that radical formation in general causes only minor structural alterations to the molecule in question. The use of isotopes with different spin and magnetic moment (in particular deuterium) may also serve a source of information. Deuteration leads to a number of protons, mainly NH - and OH, becoming substituted, and if any of these are involved in interactions with unpaired protons the resonance pattern is influeneed. The third source of information is molecular orbital calculation. The electron spin density distribution is a function in the three dimensional space based on the system's electronic wave functions. This constitutes the basis for the idea that ESR data can be correlated with

  2. Rotor damage detection by using piezoelectric impedance

    Science.gov (United States)

    Qin, Y.; Tao, Y.; Mao, Y. F.

    2016-04-01

    Rotor is a core component of rotary machinery. Once the rotor has the damage, it may lead to a major accident. Thus the quantitative rotor damage detection method based on piezoelectric impedance is studied in this paper. With the governing equation of piezoelectric transducer (PZT) in a cylindrical coordinate, the displacement along the radius direction is derived. The charge of PZT is calculated by the electric displacement. Then, by the use of the obtained displacement and charge, an analytic piezoelectric impedance model of the rotor is built. Given the circular boundary condition of a rotor, annular elements are used as the analyzed objects and spectral element method is used to set up the damage detection model. The Electro-Mechanical (E/M) coupled impedance expression of an undamaged rotor is deduced with the application of a low-cost impedance test circuit. A Taylor expansion method is used to obtain the approximate E/M coupled impedance expression for the damaged rotor. After obtaining the difference between the undamaged and damaged rotor impedance, a rotor damage detection method is proposed. This method can directly calculate the change of bending stiffness of the structural elements, it follows that the rotor damage can be effectively detected. Finally, a preset damage configuration is used for the numerical simulation. The result shows that the quantitative damage detection algorithm based on spectral element method and piezoelectric impedance proposed in this paper can identify the location and the severity of the damaged rotor accurately.

  3. Radiation damage in a high Ni weld

    International Nuclear Information System (INIS)

    WWER-1000 RPV weld metals are characterized by a high content of nickel, mostly about 1.7 mass % with content of manganese around 0.8 mass % with a very low copper content - about 0.05 mass %. In such material some late blooming phase effect should be observed during irradiation. Such typical weld material was irradiated in the experimental reactor LVR-15 in N RI Rez at the irradiation temperature 290 C degrees and at five neutron fluences from 1.5 to 9.5 *1023 m-2 (E>1 MeV). Charpy V-notch impact tests, static fracture toughness tests, tensile and hardness measurement were performed to obtain effect of neutron fluence on radiation hardening as well as embrittlement. Neutron fluence dependences of all these property changes have monotonic character but with a high neutron embrittlement exponent around 0.8. Scanning electron microscope of fracture surfaces showed no or very small portion of intercrystalline fracture. Transmission electron microscopy was performed on specimens from all neutron fluences. Only low density of black-dot damage has been observed. It is assumed that most of defect are dislocation loops. The late blooming phase which may be observed from results of mechanical properties are probably below the resolution of the used JEM-2010, i.e. 1.5 nm. (authors)

  4. Insulin Protects against Hepatic Damage Postburn

    Science.gov (United States)

    Jeschke, Marc G; Kraft, Robert; Song, Juquan; Gauglitz, Gerd G; Cox, Robert A; Brooks, Natasha C; Finnerty, Celeste C; Kulp, Gabriela A; Herndon, David N; Boehning, Darren

    2011-01-01

    Burn injury causes hepatic dysfunction associated with endoplasmic reticulum (ER) stress and induction of the unfolded protein response (UPR). ER stress/UPR leads to hepatic apoptosis and activation of the Jun-N-terminal kinase (JNK) signaling pathway, leading to vast metabolic alterations. Insulin has been shown to attenuate hepatic damage and to improve liver function. We therefore hypothesized that insulin administration exerts its effects by attenuating postburn hepatic ER stress and subsequent apoptosis. Male Sprague Dawley rats received a 60% total body surface area (TBSA) burn injury. Animals were randomized to receive saline (controls) or insulin (2.5 IU/kg q. 24 h) and euthanized at 24 and 48 h postburn. Burn injury induced dramatic changes in liver structure and function, including induction of the ER stress response, mitochondrial dysfunction, hepatocyte apoptosis, and up-regulation of inflammatory mediators. Insulin decreased hepatocyte caspase-3 activation and apoptosis significantly at 24 and 48 h postburn. Furthermore, insulin administration decreased ER stress significantly and reversed structural and functional changes in hepatocyte mitochondria. Finally, insulin attenuated the expression of inflammatory mediators IL-6, MCP-1, and CINC-1. Insulin alleviates burn-induced ER stress, hepatocyte apoptosis, mitochondrial abnormalities, and inflammation leading to improved hepatic structure and function significantly. These results support the use of insulin therapy after traumatic injury to improve patient outcomes. PMID:21267509

  5. Chemistry of radiation damage to wire chambers

    Energy Technology Data Exchange (ETDEWEB)

    Wise, J.

    1992-08-01

    Proportional counters are used to study aspects of radiation damage to wire chambers (wire aging). Principles of low-pressure, rf plasma chemistry are used to predict the plasma chemistry in electron avalanches (1 atm, dc). (1) Aging is studied in CF{sub 4}/iC{sub 4}H{sub 10} gas mixtures. Wire deposits are analyzed by Auger electron spectroscopy. An apparent cathode aging process resulting in loss of gain rather than in a self-sustained current is observed in CF{sub 4}-rich gases. A four-part model considering plasma polymerization of the hydrocarbon, etching of wire deposits by CF{sub 4}, acceleration of deposition processes in strongly etching environments, and reactivity of the wire surface is developed to understand anode wire aging in CF{sub 4}/iC{sub 4}H{sub 10} gases. Practical guidelines suggested by the model are discussed. (2) Data are presented to suggest that trace amounts of Freons do not affect aging rates in either dimethyl ether or Ar/C{sub 2}H{sub 6}. Apparent loss of gain is explained by attachment of primary electrons to a continuously increasing concentration of Freon 11 (CCl{sub 3}F) in the counter gas. An increase in the concentration of Freon 11 in dimethyl ether is caused by a distillation process in the gas supply bottle and is a natural consequence of the unequal volatilities of the two compounds.

  6. Chemistry of radiation damage to wire chambers

    International Nuclear Information System (INIS)

    Proportional counters are used to study aspects of radiation damage to wire chambers (wire aging). Principles of low-pressure, rf plasma chemistry are used to predict the plasma chemistry in electron avalanches (1 atm, dc). (1) Aging is studied in CF4/iC4H10 gas mixtures. Wire deposits are analyzed by Auger electron spectroscopy. An apparent cathode aging process resulting in loss of gain rather than in a self-sustained current is observed in CF4-rich gases. A four-part model considering plasma polymerization of the hydrocarbon, etching of wire deposits by CF4, acceleration of deposition processes in strongly etching environments, and reactivity of the wire surface is developed to understand anode wire aging in CF4/iC4H10 gases. Practical guidelines suggested by the model are discussed. (2) Data are presented to suggest that trace amounts of Freons do not affect aging rates in either dimethyl ether or Ar/C2H6. Apparent loss of gain is explained by attachment of primary electrons to a continuously increasing concentration of Freon 11 (CCl3F) in the counter gas. An increase in the concentration of Freon 11 in dimethyl ether is caused by a distillation process in the gas supply bottle and is a natural consequence of the unequal volatilities of the two compounds

  7. Convolution Sum Discrete Process Neural Network and Its Application in Aeroengine Exhausted Gas Temperature Prediction%卷积和离散过程神经网络及其在航空发动机排气温度预测中的应用

    Institute of Scientific and Technical Information of China (English)

    钟诗胜; 雷达; 丁刚

    2012-01-01

    The changing process of aeroengine exhausted gas temperature (EGT) is affected by complicated nonlinear time varying factors, which make it difficult to construct its mathematic model. To cope with this issue, a convolution sum discrete process neural network (CSDPNN) model is proposed and used for EGT prediction. This model directly utilizes discrete sampling points as input, and uses the convolution sum to deal with the time accumulation process. Compared with the process neural network(PNN)with continuous function inputs, there is ho need to fit the sampling points to get input functions and then to decompose them by orthogonal basis functions which can lead to precision loss. Therefore, this model can a-chieve higher prediction precision. A learning algorithm for this model is also developed, and the model is explained and validated via Mackey-Glass chaos time series prediction. Then, the model is adopted to predict a real EGT time series. The prediction results are compared with results obtained by the process neural network with function inputs and the traditional artificial neural network(ANN), which proves that CSDPNN model has higher precision than the other two networks, and it exhibits good adaptability to EGT prediction. This model offers an effective method for real EGT prediction.%针对航空发动机排气温度的变化过程受复杂非线性时变因素的影响而难以用精确数学模型描述的问题,提出了卷积和离散过程神经网络(CSDPNN)模型,并将其应用于航空发动机排气温度(EGT)预测.该模型以离散样本作为直接输入,采用卷积和算法实现对时间累积效应的处理.相较于以连续函数作为输入的过程神经网络(PNN),不需要拟合离散样本得到连续函数后进行正交基展开,减少了精度损失,具有更高的预测精度.给出了卷积和离散过程神经网络模型的学习算法,并通过对Mackey-Glass混沌时间序列的预测对提出的方法进行应用说明

  8. DNA Damage Signals and Space Radiation Risk

    Science.gov (United States)

    Cucinotta, Francis A.

    2011-01-01

    Space radiation is comprised of high-energy and charge (HZE) nuclei and protons. The initial DNA damage from HZE nuclei is qualitatively different from X-rays or gamma rays due to the clustering of damage sites which increases their complexity. Clustering of DNA damage occurs on several scales. First there is clustering of single strand breaks (SSB), double strand breaks (DSB), and base damage within a few to several hundred base pairs (bp). A second form of damage clustering occurs on the scale of a few kbp where several DSB?s may be induced by single HZE nuclei. These forms of damage clusters do not occur at low to moderate doses of X-rays or gamma rays thus presenting new challenges to DNA repair systems. We review current knowledge of differences that occur in DNA repair pathways for different types of radiation and possible relationships to mutations, chromosomal aberrations and cancer risks.

  9. Damage Tensor Analysis on Regional Seismic Status

    Institute of Scientific and Technical Information of China (English)

    Zhong Jimao; Cheng Wanzheng

    2006-01-01

    In this paper, we researched the regional seismic status by using theories of the Damage Mechanics. The macroscopic damage status of the earth crust block, which is caused by earthquake fracture, is described with several concepts-the damage degree, the damage rate and the strain rate. In the earthquake process, the average strain rate of the studied block is equal to the sum of all seismic moment tensors of the earthquakes taking place in unit time and physical volume. To describe the anisotropy of microdamage of the crust block, we use the damage tensor that is expressed in the fissure density. By means of the transformation from the focal coordinate system to the observation system, we obtained the external normal vector of the focal fault plane expressed in its observation system and obtained the macrodamage degree of the researched block, which is calculated in dyadic. This provides a new analysis method for recognizing the underground damage status and the stress status.

  10. COMBINED DAMAGE FRACTURE CRITERIA FOR PIEZOELECTRIC CERAMICS

    Institute of Scientific and Technical Information of China (English)

    Yang Xinhua; Chen Chuanyao; Hu Yuantai; Wang Cheng

    2005-01-01

    Mechanical and electrical damages are introduced to study the fracture mechanics of piezoelectric ceramics in this paper. Two kinds of piezoelectric fracture criteria are established using the method of least squares combined with a damage analysis of the well-known piezoelectric fracture experiments of Park and Sun's. One is based on a linear combination of the mechanical and electrical damages and the other on their nonlinear combination. When the combined damage D is up to its critical value Dc, piezoelectric fracture occurs. It is found from the qualitative comparison of the numerical results with the experimental data that the nonlinearly combined damage fracture criterion can give a better prediction of piezoelectric fracture. And it is concluded from the nonlinearly combined damage fracture criterion that a negative electric field impedes fracture whereas the effect of a positive electric field on fracture depends on its magnitude.

  11. Subclinical organ damage and cardiovascular risk prediction

    DEFF Research Database (Denmark)

    Sehestedt, Thomas; Olsen, Michael H

    2010-01-01

    ) investigated which and how many markers to measure and (iv) finally discussed whether measuring subclinical organ damage provided benefits beyond risk prediction. In conclusion, more studies and if possible randomized studies are needed to investigate (i) the importance of markers of subclinical organ damage......Traditional cardiovascular risk factors have poor prognostic value for individuals and screening for subclinical organ damage has been recommended in hypertension in recent guidelines. The aim of this review was to investigate the clinical impact of the additive prognostic information provided...... by measuring subclinical organ damage. We have (i) reviewed recent studies linking markers of subclinical organ damage in the heart, blood vessels and kidney to cardiovascular risk; (ii) discussed the evidence for improvement in cardiovascular risk prediction using markers of subclinical organ damage; (iii...

  12. Using DNA damage to monitor water environment

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    DNA damage of aquatic organisms living in polluted environments can be used as a biomarker of the genotoxicity of toxic agents to organisms. This technique has been playing an important role in ecotoxicological study and environmental risk assessment. In this article, main types of DNA damage caused by pollutants in water environments were reviewed; methods of detecting DNA damage were also documented for water environmental monitoring.

  13. Economic evaluation of subsidence damage mitigation techniques

    International Nuclear Information System (INIS)

    Coal mining in Illinois has resulted in many structures being exposed to subsidence damage. Damage mitigation techniques (DMT) applied in the foundation design/construction have proven successful in minimizing damage in several test cases. To determine the practicality of these techniques, the costs of their application are investigated. The DMT costs are compared to foundation and total house costs for various classes and sizes of houses. An economical and effective subsidence resistant foundation construction is proposed

  14. On Damage Characterization of a Steel Sheet

    OpenAIRE

    Guzmán Inostroza, Carlos Felipe; Habraken, Anne

    2014-01-01

    Ductile damage is a physical phenomena which involves progressive deterioration of mechanical properties of metals, when undergoing high deformations. Compared to plasticity, the physical mechanisms behind damage are more complex and the microscale is not longer negligible. In mathematical damage models, founding an optimal set of material parameters can be a hard task due to the strong coupling and non-linearity of the equations. An identification strategy is then crucial to arrive to a gene...

  15. Focused Ion Beam tomography of the damage produced in zirconia toughened alumina

    OpenAIRE

    Rodríguez Rivera, Cristina Marie

    2014-01-01

    Two different three-dimensional reconstructions of the crack propagation induced by mechanical testing in zirconia-toughened alumina (ZTA) were made. The first tomography is of the damage caused by an indentation, with the objective to visualize how the crack propagates inside of the material and how it interacts with the different phases that compose the material. The second reconstruction is based on the damage caused by a scratch test on the surface of the material and the fissures gene...

  16. Laser-induced damage of 1064-nm narrow-band interference filters under different laser modes

    Institute of Scientific and Technical Information of China (English)

    Weidong Gao(高卫东); Hongbo He(贺洪波); Jianda Shao(邵建达); Zhengxiu Fan(范正修)

    2004-01-01

    The laser-induced damage behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running laser mode.The absorption measurement of such coatings has been performed by surface thermal lensing(STL)technique.The relationship between damage morphology and absorption under the two different laser modes was studied in detail.The explanation was given by the standing-wave distribution theory.

  17. Evolution of bulk damage initiation in DKDP

    Science.gov (United States)

    Carr, Christopher W.; McMillian, T. H.; Staggs, Mike C.; Radousky, Harry B.; Demos, Stavros G.

    2003-05-01

    We investigate the evolution of laser-induced damage initiated in the bulk of DKDP crystals using in-situ microscopy. Experimental results indicate that at peek fluences greater than 10 J/cm2, damage sites are formed with increasing number as a function of the laser fluence. Following plasma formation, cracks are observed which grow in size for tens of seconds after the termination of the laser pulse. Subsequent irradiation leads to modest increase in size only during the initial 2-5 pulses. Experimental results suggest that there is also relaxation of the stresses adjacent to a damage site for several hours after initial damage.

  18. CHARACTERIZATION OF THERMALLY DAMAGED LX-17

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P C

    2007-07-11

    Thermal damage was applied to LX-17 at 190 C for several hours. The damaged LX-17 samples, after cooled down to room temperature, were characterized for their material properties (density, porosity, permeability, moduli), safety, and performance. Weight losses upon thermal exposure were insignificant (< 0.1% wt.). The damaged LX-17 samples expanded, resulting in a bulk density reduction of 4.3%. Subsequent detonation measurements (cylinder tests) were conducted on the thermally-damaged LX-17 samples. The results showed that the fractions of damaged LX-17 reacted were slightly lower than those of pristine LX-17. The thermally damaged LX-17 had a detonation velocity of 7.315 mm/{micro}s, lower than that (7.638 mm/{micro}s) of pristine LX-17. Detonation energy density for the damaged LX-17 was 5.08 kJ/cm{sup 3}, about 9.0% lower than the detonation energy density of 5.50 kJ/cm{sup 3} for the pristine LX-17. The break-out curves showed reaction zone lengths for pristine LX-17 and damaged LX-17 were similar but the damaged samples had ragged detonation fronts.

  19. Studies on the Neutron Radiation Damage Equivalence

    Directory of Open Access Journals (Sweden)

    ZOU De-hui

    2015-01-01

    Full Text Available To establish a unified standard of the evaluation of different sources of radiation damage, the neutron radiation damage equivalent standard source was determined both at home and abroad, and a lot of equivalence research work was done for making weapons anti neutron radiation performance examination and acceptance basis. The theoretical research progress was combed according to the relationship between the displacement damage function and the radiation source spectra ,and the experimental research progress was combed from the basic experimental methods, the controlling trend of effect parameters and field parameters. The experiment method to reduce the uncertainty was discussed, and present the research directions of radiation damage equivalence.

  20. Structural damage assessment as an identification problem

    Science.gov (United States)

    Hajela, Prabhat; Soeiro, F. J.

    1989-01-01

    Damage assessment of structural assemblies is treated as an identification problem. A brief review of identification methods is first presented with particular focus on the output error approach. The use of numerical optimization methods in identifying the location and extent of damage in structures is studied. The influence of damage on eigenmode shapes and static displacements is explored as a means of formulating a measure of damage in the structure. Preliminary results obtained in this study are presented and special attention is directed at the shortcomings associated with the nonlinear programming approach to solving the optimization problem.