Evolution of dispersal in spatially and temporally variable environments: The importance of life cycles.

PubMed

Massol, François; Débarre, Florence

2015-07-01

Spatiotemporal variability of the environment is bound to affect the evolution of dispersal, and yet model predictions strongly differ on this particular effect. Recent studies on the evolution of local adaptation have shown that the life cycle chosen to model the selective effects of spatiotemporal variability of the environment is a critical factor determining evolutionary outcomes. Here, we investigate the effect of the order of events in the life cycle on the evolution of unconditional dispersal in a spatially heterogeneous, temporally varying landscape. Our results show that the occurrence of intermediate singular strategies and disruptive selection are conditioned by the temporal autocorrelation of the environment and by the life cycle. Life cycles with dispersal of adults versus dispersal of juveniles, local versus global density regulation, give radically different evolutionary outcomes that include selection for total philopatry, evolutionary bistability, selection for intermediate stable states, and evolutionary branching points. Our results highlight the importance of accounting for life-cycle specifics when predicting the effects of the environment on evolutionarily selected trait values, such as dispersal, as well as the need to check the robustness of model conclusions against modifications of the life cycle. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Fitness and Individuality in Complex Life Cycles.

PubMed

Herron, Matthew D

2016-12-01

Complex life cycles are common in the eukaryotic world, and they complicate the question of how to define individuality. Using a bottom-up, gene-centric approach, I consider the concept of fitness in the context of complex life cycles. I analyze the fitness effects of an allele (or a trait) on different biological units within a complex life history and how these effects drive evolutionary change within populations. Based on these effects, I attempt to construct a concept of fitness that accurately predicts evolutionary change in the context of complex life cycles.

Preliminary study of thermomechanical fatigue of polycrystalline MAR-M 200

NASA Technical Reports Server (NTRS)

Bill, R. C.; Verrilli, M. J.; Mcgaw, M. A.; Halford, G. R.

1984-01-01

Thermomechanical fatigue (TMF) experiments were conducted on polycrystalline MAR-M 200 over a cyclic temperature range of 500 to 1000 C. Inelastic strain ranges of 0.03 to 0.2 percent were imposed on the specimens. The TMF lives were found to be significantly shorter than isothermal low-cycle-fatigue (LCF) life at the maximum cycle temperature, and in-phase cycling was more damaging than out-of-phase cycling. Extensive crack tip oxidation appeared to play a role in promoting the severity of in-phase cycling. Carbide particle - matrix interface cracking was also observed after in-phase TMF cycling. The applicability of various life prediction models to the TMF results obtained was assessed. It was concluded that current life prediction models based on isothermal data as input must be modified to be applicable to the TMF results.

Multiscale Fatigue Life Prediction for Composite Panels

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Yarrington, Phillip W.; Arnold, Steven M.

2012-01-01

Fatigue life prediction capabilities have been incorporated into the HyperSizer Composite Analysis and Structural Sizing Software. The fatigue damage model is introduced at the fiber/matrix constituent scale through HyperSizer s coupling with NASA s MAC/GMC micromechanics software. This enables prediction of the micro scale damage progression throughout stiffened and sandwich panels as a function of cycles leading ultimately to simulated panel failure. The fatigue model implementation uses a cycle jumping technique such that, rather than applying a specified number of additional cycles, a specified local damage increment is specified and the number of additional cycles to reach this damage increment is calculated. In this way, the effect of stress redistribution due to damage-induced stiffness change is captured, but the fatigue simulations remain computationally efficient. The model is compared to experimental fatigue life data for two composite facesheet/foam core sandwich panels, demonstrating very good agreement.

Turbine blade tip durability analysis

NASA Technical Reports Server (NTRS)

Mcknight, R. L.; Laflen, J. H.; Spamer, G. T.

1981-01-01

An air-cooled turbine blade from an aircraft gas turbine engine chosen for its history of cracking was subjected to advanced analytical and life-prediction techniques. The utility of advanced structural analysis techniques and advanced life-prediction techniques in the life assessment of hot section components are verified. Three dimensional heat transfer and stress analyses were applied to the turbine blade mission cycle and the results were input into advanced life-prediction theories. Shortcut analytical techniques were developed. The proposed life-prediction theories are evaluated.

Integrating GLL-Weibull Distribution Within a Bayesian Framework for Life Prediction of Shape Memory Alloy Spring Undergoing Thermo-mechanical Fatigue

NASA Astrophysics Data System (ADS)

Kundu, Pradeep; Nath, Tameshwer; Palani, I. A.; Lad, Bhupesh K.

2018-06-01

The present paper tackles an important but unmapped problem of the reliability estimations of smart materials. First, an experimental setup is developed for accelerated life testing of the shape memory alloy (SMA) springs. Generalized log-linear Weibull (GLL-Weibull) distribution-based novel approach is then developed for SMA spring life estimation. Applied stimulus (voltage), elongation and cycles of operation are used as inputs for the life prediction model. The values of the parameter coefficients of the model provide better interpretability compared to artificial intelligence based life prediction approaches. In addition, the model also considers the effect of operating conditions, making it generic for a range of the operating conditions. Moreover, a Bayesian framework is used to continuously update the prediction with the actual degradation value of the springs, thereby reducing the uncertainty in the data and improving the prediction accuracy. In addition, the deterioration of material with number of cycles is also investigated using thermogravimetric analysis and scanning electron microscopy.

Thermal Cycling Life Prediction of Sn-3.0Ag-0.5Cu Solder Joint Using Type-I Censored Data

PubMed Central

Mi, Jinhua; Yang, Yuan-Jian; Huang, Hong-Zhong

2014-01-01

Because solder joint interconnections are the weaknesses of microelectronic packaging, their reliability has great influence on the reliability of the entire packaging structure. Based on an accelerated life test the reliability assessment and life prediction of lead-free solder joints using Weibull distribution are investigated. The type-I interval censored lifetime data were collected from a thermal cycling test, which was implemented on microelectronic packaging with lead-free ball grid array (BGA) and fine-pitch ball grid array (FBGA) interconnection structures. The number of cycles to failure of lead-free solder joints is predicted by using a modified Engelmaier fatigue life model and a type-I censored data processing method. Then, the Pan model is employed to calculate the acceleration factor of this test. A comparison of life predictions between the proposed method and the ones calculated directly by Matlab and Minitab is conducted to demonstrate the practicability and effectiveness of the proposed method. At last, failure analysis and microstructure evolution of lead-free solders are carried out to provide useful guidance for the regular maintenance, replacement of substructure, and subsequent processing of electronic products. PMID:25121138

Predicting responses to climate change requires all life-history stages.

PubMed

Zeigler, Sara

2013-01-01

In Focus: Radchuk, V., Turlure, C. & Schtickzelle, N. (2013) Each life stage matters: the importance of assessing response to climate change over the complete life cycle in butterflies. Journal of Animal Ecology, 82, 275-285. Population-level responses to climate change depend on many factors, including unexpected interactions among life history attributes; however, few studies examine climate change impacts over complete life cycles of focal species. Radchuk, Turlure & Schtickzelle () used experimental and modelling approaches to predict population dynamics for the bog fritillary butterfly under warming scenarios. Although they found that warming improved fertility and survival of all stages with one exception, populations were predicted to decline because overwintering larvae, whose survival declined with warming, were disproportionately important contributors to population growth. This underscores the importance of considering all life history stages in analyses of climate change's effects on population dynamics. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Some effects of thermal-cycle-induced deformation in rocket thrust chambers

NASA Technical Reports Server (NTRS)

Hannum, N. P.; Price, R. G., Jr.

1981-01-01

The deformation process observed in the hot gas side wall of rocket combustion chambers was investigaged for three different liner materials. Five thrust chambers were cycled to failure by using hydrogen and oxygen as propellants at a chamber pressure of 4.14 MN/cu m. The deformation was observed nondestructively at midlife points and destructively after failure occurred. The cyclic life results are presented with an accompanying discussion about the problems of life prediction associated with the types of failures encountered in the present work. Data indicating the deformation of the thrust chamber liner as cycles are accumulated are presented for each of the test thrust chambers. From these deformation data and observation of the failure sites it is evident that modeling the failure process as classic low cycle thermal fatigue is inadequate as a life prediction method.

Interior Fracture Mechanism Analysis and Fatigue Life Prediction of Surface-Hardened Gear Steel under Axial Loading.

PubMed

Li, Wei; Deng, Hailong; Liu, Pengfei

2016-10-18

The interior defect-induced fracture of surface-hardened metallic materials in the long life region has become a key issue on engineering design. In the present study, the axial loading test with fully reversed condition was performed to examine the fatigue property of a surface-carburized low alloy gear steel in the long life region. Results show that this steel represents the duplex S-N (stress-number of cycles) characteristics without conventional fatigue limit related to 10⁷ cycles. Fatigue cracks are all originated from the interior inclusions in the matrix region due to the inhabitation effect of carburized layer. The inclusion induced fracture with fisheye occurs in the short life region below 5 × 10⁵ cycles, whereas the inclusion induced fracture with fine granular area (FGA) and fisheye occurs in the long life region beyond 10⁶ cycles. The stress intensity factor range at the front of FGA can be regarded as the threshold value controlling stable growth of interior long crack. The evaluated maximum inclusion size in the effective damage volume of specimen is about 27.29 μm. Considering the size relationships between fisheye and FGA, and inclusion, the developed life prediction method involving crack growth can be acceptable on the basis of the good agreement between the predicted and experimental results.

Strainrange partitioning behavior of the nickel-base superalloys, Rene' 80 and in 100

NASA Technical Reports Server (NTRS)

Halford, G. R.; Nachtigall, A. J.

1978-01-01

A study was made to assess the ability of the method of Strainrange Partitioning (SRP) to both correlate and predict high-temperature, low cycle fatigue lives of nickel base superalloys for gas turbine applications. The partitioned strainrange versus life relationships for uncoated Rene' 80 and cast IN 100 were also determined from the ductility normalized-Strainrange Partitioning equations. These were used to predict the cyclic lives of the baseline tests. The life predictability of the method was verified for cast IN 100 by applying the baseline results to the cyclic life prediction of a series of complex strain cycling tests with multiple hold periods at constant strain. It was concluded that the method of SRP can correlate and predict the cyclic lives of laboratory specimens of the nickel base superalloys evaluated in this program.

Solar-cell interconnect design for terrestrial photovoltaic modules

NASA Technical Reports Server (NTRS)

Mon, G. R.; Moore, D. M.; Ross, R. G., Jr.

1984-01-01

Useful solar cell interconnect reliability design and life prediction algorithms are presented, together with experimental data indicating that the classical strain cycle (fatigue) curve for the interconnect material does not account for the statistical scatter that is required in reliability predictions. This shortcoming is presently addressed by fitting a functional form to experimental cumulative interconnect failure rate data, which thereby yields statistical fatigue curves enabling not only the prediction of cumulative interconnect failures during the design life of an array field, but also the quantitative interpretation of data from accelerated thermal cycling tests. Optimal interconnect cost reliability design algorithms are also derived which may allow the minimization of energy cost over the design life of the array field.

Solar-cell interconnect design for terrestrial photovoltaic modules

NASA Astrophysics Data System (ADS)

Mon, G. R.; Moore, D. M.; Ross, R. G., Jr.

1984-11-01

Useful solar cell interconnect reliability design and life prediction algorithms are presented, together with experimental data indicating that the classical strain cycle (fatigue) curve for the interconnect material does not account for the statistical scatter that is required in reliability predictions. This shortcoming is presently addressed by fitting a functional form to experimental cumulative interconnect failure rate data, which thereby yields statistical fatigue curves enabling not only the prediction of cumulative interconnect failures during the design life of an array field, but also the quantitative interpretation of data from accelerated thermal cycling tests. Optimal interconnect cost reliability design algorithms are also derived which may allow the minimization of energy cost over the design life of the array field.

A comparison of major petroleum life cycle models

EPA Science Inventory

Many organizations have attempted to develop an accurate well-to-pump life cycle model of petroleum products in order to inform decision makers of the consequences of its use. Our paper studies five of these models, demonstrating the differences in their predictions and attemptin...

Statistical analysis of lithium iron sulfide status cell cycle life and failure mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gay, E.C.; Battles, J.E.; Miller, W.E.

1983-08-01

A statistical model was developed for life cycle testing of electrochemical cell life cycle trials and verified experimentally. The Weibull distribution was selected to predict the end of life for a cell, based on a 20 percent loss of initial stabilized capacity or a decrease to less than 95 percent coulombic efficiency. Groups of 12 or more Li-alloy/FeS cells were cycled to determine the mean time to failure (MTTF) and also to identify the failure modes. The cells were all full size electric vehicle batteries with 150-350 A-hr capacity. The Weibull shape factors were determined and verified in prediction ofmore » the number of cell failures in two 10 cell modules. The short circuit failure in the cells with BN-felt and MgO powder separators were found to be caused by the formation of Li-Al protrusions that penetrated the BN-felt separators, and the extrusion of active material at the edge of the electrodes.« less

Evaluation program for secondary spacecraft cells: Cycle life test

NASA Technical Reports Server (NTRS)

Harkness, J. D.

1979-01-01

The service life and storage stability for several storage batteries were determined. The batteries included silver-zinc batteries, nickel-cadmium batteries, and silver-cadmium batteries. The cell performance characteristics and limitations are to be used by spacecraft power systems planners and designers. A statistical analysis of the life cycle prediction and cause of failure versus test conditions is presented.

[Life cycle of the taiga tick ixodes persulcatus in taiga forests of the eastern Sayan Plateau].

PubMed

Korotkov, Iu S

2014-01-01

The Ixodes persulcatus life cycle has been studied in natural environments of taiga fo- rests in The Eastern Sayan Plateau (56 10' N, 91 30' E). Engorged larvae and nymphs de- velop with a morphogenetic diapause or without diapause, with ratio of these two ways of development for larvae and nymphs 77.25/22.75% and 43.43/56.57%, respectively. The hypothetic season hemipopulation consists of 34.5 +/- 4.5, 50.1 +/- 1.3, 13.2 +/- 4.0 n 2.2% of unfed imagoes, completing 3-year, 4-year, 5-year, and 6-year life cycles, respectively. Mean life span is 3.83 +/- 0.10 years per generation. The "life table" predicting the probability to complete life cycle through phases from egg to adult, was developed.

Practical theories for service life prediction of critical aerospace structural components

NASA Technical Reports Server (NTRS)

Ko, William L.; Monaghan, Richard C.; Jackson, Raymond H.

1992-01-01

A new second-order theory was developed for predicting the service lives of aerospace structural components. The predictions based on this new theory were compared with those based on the Ko first-order theory and the classical theory of service life predictions. The new theory gives very accurate service life predictions. An equivalent constant-amplitude stress cycle method was proposed for representing the random load spectrum for crack growth calculations. This method predicts the most conservative service life. The proposed use of minimum detectable crack size, instead of proof load established crack size as an initial crack size for crack growth calculations, could give a more realistic service life.

Generation of Finite Life Distributional Goodman Diagrams for Reliability Prediction

NASA Technical Reports Server (NTRS)

Kececioglu, D.; Guerrieri, W. N.

1971-01-01

The methodology of developing finite life distributional Goodman diagrams and surfaces is described for presenting allowable combinations of alternating stress and mean stress to the design engineer. The combined stress condition is that of an alternating bending stress and a constant shear stress. The finite life Goodman diagrams and surfaces are created from strength distributions developed at various ratios of alternating to mean stress at particular cycle life values. The conclusions indicate that the Von Mises-Hencky ellipse, for cycle life values above 1000 cycles, is an adequate model of the finite life Goodman diagram. In addition, suggestions are made which reduce the number of experimental data points required in a fatigue data acquisition program.

A New Multiaxial High-Cycle Fatigue Criterion Based on the Critical Plane for Ductile and Brittle Materials

NASA Astrophysics Data System (ADS)

Wang, Cong; Shang, De-Guang; Wang, Xiao-Wei

2015-02-01

An improved high-cycle multiaxial fatigue criterion based on the critical plane was proposed in this paper. The critical plane was defined as the plane of maximum shear stress (MSS) in the proposed multiaxial fatigue criterion, which is different from the traditional critical plane based on the MSS amplitude. The proposed criterion was extended as a fatigue life prediction model that can be applicable for ductile and brittle materials. The fatigue life prediction model based on the proposed high-cycle multiaxial fatigue criterion was validated with experimental results obtained from the test of 7075-T651 aluminum alloy and some references.

A comparison of major petroleum life cycle models | Science ...

EPA Pesticide Factsheets

Many organizations have attempted to develop an accurate well-to-pump life cycle model of petroleum products in order to inform decision makers of the consequences of its use. Our paper studies five of these models, demonstrating the differences in their predictions and attempting to evaluate their data quality. Carbon dioxide well-to-pump emissions for gasoline showed a variation of 35 %, and other pollutants such as ammonia and particulate matter varied up to 100 %. Differences in allocation do not appear to explain differences in predictions. Effects of these deviations on well-to-wheels passenger vehicle and truck transportation life cycle models may be minimal for effects such as global warming potential (6 % spread), but for respiratory effects of criteria pollutants (41 % spread) and other impact categories, they can be significant. A data quality assessment of the models’ documentation revealed real differences between models in temporal and geographic representativeness, completeness, as well as transparency. Stakeholders may need to consider carefully the tradeoffs inherent when selecting a model to conduct life cycle assessments for systems that make heavy use of petroleum products. This is a qualitative and quantitative comparison of petroleum LCA models intended for an expert audience interested in better understanding the data quality of existing petroleum life cycle models and the quantitative differences between these models.

Life prediction of thermomechanical fatigue using total strain version of strainrange partitioning (SRP): A proposal

NASA Technical Reports Server (NTRS)

Saltsman, James F.; Halford, Gary R.

1988-01-01

A method is proposed (without experimental verification) for extending the total strain version of Strainrange Partitioning (TS-SRP) to predict the lives of thermomechanical fatigue (TMF) cycles. The principal feature of TS SRP is the determination of the time-temperature-waveshape dependent elastic strainrange versus life lines that are added subsequently to the classical inelastic strainrange versus life lines to form the total strainrange versus life relations. The procedure is based on a derived relation between failure and flow behavior. Failure behavior is represented by conventional SRP inelastic strainrange versus cyclic life relations, while flow behavior is captured in terms of the cyclic stress-strain response characteristics. Stress-strain response is calculated from simple equations developed from approximations to more complex cyclic constitutive models. For applications to TMF life prediction, a new testing technique, bithermal cycling, is proposed as a means for generating the inelastic strainrange versus life relations. Flow relations for use in predicting TMF lives would normally be obtained from approximations to complex thermomechanical constitutive models. Bithermal flow testing is also proposed as an alternative to thermomechanical flow testing at low strainranges where the hysteresis loop is difficult to analyze.

Procedures for characterizing an alloy and predicting cyclic life with the total strain version of Strainrange Partitioning

NASA Technical Reports Server (NTRS)

Saltsman, James F.; Halford, Gary R.

1989-01-01

Procedures are presented for characterizing an alloy and predicting cyclic life for isothermal and thermomechanical fatigue conditions by using the total strain version of strainrange partitioning (TS-SRP). Numerical examples are given. Two independent alloy characteristics are deemed important: failure behavior, as reflected by the inelastic strainrange versus cyclic life relations; and flow behavior, as indicated by the cyclic stress-strain-time response (i.e., the constitutive behavior). Failure behavior is characterized by conducting creep-fatigue tests in the strain regime, wherein the testing times are reasonably short and the inelastic strains are large enough to be determined accurately. At large strainranges, stress-hold, strain-limited tests are preferred because a high rate of creep damage per cycle is inherent in this type of test. At small strainranges, strain-hold cycles are more appropriate. Flow behavior is characterized by conducting tests wherein the specimen is usually cycled far short of failure and the wave shape is appropriate for the duty cycle of interest. In characterizing an alloy pure fatigue, or PP, failure tests are conducted first. Then depending on the needs of the analyst a series of creep-fatigue tests are conducted. As many of the three generic SRP cycles are featured as are required to characterize the influence of creep on fatigue life (i.e., CP, PC, and CC cycles, respectively, for tensile creep only, compressive creep only, and both tensile and compressive creep). Any mean stress effects on life also must be determined and accounted for when determining the SRP inelastic strainrange versus life relations for cycles featuring creep. This is particularly true for small strainranges. The life relations thus are established for a theoretical zero mean stress condition.

Life prediction of thermal-mechanical fatigue using strainrange partitioning

NASA Technical Reports Server (NTRS)

Halford, G. R.; Manson, S. S.

1975-01-01

This paper describes the applicability of the method of Strainrange Partitioning to the life prediction of thermal-mechanical strain-cycling fatigue. An in-phase test on 316 stainless steel is analyzed as an illustrative example. The observed life is in excellent agreement with the life predicted by the method using the recently proposed Step-Stress Method of experimental partitioning, the Interaction Damage Rule, and the life relationships determined at an isothermal temperature of 705 C. Implications of the present study are discussed relative to the general thermal fatigue problem.

Life prediction of thermal-mechanical fatigue using strain-range partitioning

NASA Technical Reports Server (NTRS)

Halford, G. R.; Manson, S. S.

1975-01-01

The applicability is described of the method of Strainrange Partitioning to the life prediction of thermal-mechanical strain-cycling fatigue. An in-phase test on 316 stainless steel is analyzed as an illustrative example. The observed life is in excellent agreement with the life predicted by the method using the recently proposed Step-Stress Method of experimental partitioning, the Interation Damage Rule, and the life relationships determined at an isothermal temperature of 705 C. Implications of the study are discussed relative to the general thermal fatigue problem.

Research on strength attenuation law of concrete in freezing - thawing environment

NASA Astrophysics Data System (ADS)

Xiao, qianhui; Cao, zhiyuan; Li, qiang

2018-03-01

By rapid freezing and thawing method, the experiments of concrete have been 300 freeze-thaw cycles specimens in the water. The cubic compression strength value under different freeze-thaw cycles was measured. By analyzing the test results, the water-binder ratio of the concrete under freeze-thaw environments, fly ash and air entraining agent is selected dosage recommendations. The exponential attenuation prediction model and life prediction model of compression strength of concrete under freezing-thawing cycles considering the factors of water-binder ratio, fly ash content and air-entraining agent dosage were established. The model provides the basis for predicting the durability life of concrete under freezing-thawing environment. It also provides experimental basis and references for further research on concrete structures with antifreeze requirements.

Application of an Energy-Based Life Prediction Model to Bithermal and Thermomechanical Fatigue

NASA Technical Reports Server (NTRS)

Radhakrishnan, V. M.; Kalluri, Sreeramesh; Halford, Gary R.

1994-01-01

The inelastic hysteresis energy applied to the material in a cycle is used as the basis for predicting nonisothermal fatigue life of a wrought cobalt-base superalloy, Haynes 188, from isothermal fatigue data. Damage functions that account for hold-time effects and time-dependent environmental phenomena such as oxidation and hot corrosion are proposed in terms of the inelastic hysteresis energy per cycle. The proposed damage functions are used to predict the bithermal and thermomechanical fatigue lives of Haynes 188 between 316 and 760 C from isothermal fatigue data. Predicted fatigue lives of all but two of the nonisothermal tests are within a factor of 1.5 of the experimentally observed lives.

[Prediction method of rural landscape pattern evolution based on life cycle: a case study of Jinjing Town, Hunan Province, China].

PubMed

Ji, Xiang; Liu, Li-Ming; Li, Hong-Qing

2014-11-01

Taking Jinjing Town in Dongting Lake area as a case, this paper analyzed the evolution of rural landscape patterns by means of life cycle theory, simulated the evolution cycle curve, and calculated its evolution period, then combining CA-Markov model, a complete prediction model was built based on the rule of rural landscape change. The results showed that rural settlement and paddy landscapes of Jinjing Town would change most in 2020, with the rural settlement landscape increased to 1194.01 hm2 and paddy landscape greatly reduced to 3090.24 hm2. The quantitative and spatial prediction accuracies of the model were up to 99.3% and 96.4%, respectively, being more explicit than single CA-Markov model. The prediction model of rural landscape patterns change proposed in this paper would be helpful for rural landscape planning in future.

A New Ductility Exhaustion Model for High Temperature Low Cycle Fatigue Life Prediction of Turbine Disk Alloys

NASA Astrophysics Data System (ADS)

Zhu, Shun-Peng; Huang, Hong-Zhong; Li, Haiqing; Sun, Rui; Zuo, Ming J.

2011-06-01

Based on ductility exhaustion theory and the generalized energy-based damage parameter, a new viscosity-based life prediction model is introduced to account for the mean strain/stress effects in the low cycle fatigue regime. The loading waveform parameters and cyclic hardening effects are also incorporated within this model. It is assumed that damage accrues by means of viscous flow and ductility consumption is only related to plastic strain and creep strain under high temperature low cycle fatigue conditions. In the developed model, dynamic viscosity is used to describe the flow behavior. This model provides a better prediction of Superalloy GH4133's fatigue behavior when compared to Goswami's ductility model and the generalized damage parameter. Under non-zero mean strain conditions, moreover, the proposed model provides more accurate predictions of Superalloy GH4133's fatigue behavior than that with zero mean strains.

How can mortality increase population size? A test of two mechanistic hypotheses.

PubMed

McIntire, Kristina M; Juliano, Steven A

2018-05-03

Overcompensation occurs when added mortality increases survival to the next life-cycle stage. Overcompensation can contribute to the Hydra Effect, wherein added mortality increases equilibrium population size. One hypothesis for overcompensation is that added mortality eases density-dependence, increasing survival to adulthood ("temporal separation of mortality and density dependence"). Mortality early in the life cycle is therefore predicted to cause overcompensation, whereas mortality later in the life cycle is not. Another hypothesis for overcompensation is that threat of mortality (e.g., from predation) causes behavioral changes that reduce overexploitation of resources, allowing resource recovery, and increasing production of adults ("prudent resource exploitation"). Behaviorally active predation cues alone are therefore predicted to cause overcompensation. We tested these predictions in two experiments with larvae of two species of Aedes. As predicted, early mortality yielded greater production of adults, and of adult females, and greater estimated rate of population increase than did later mortality. Addition of water-borne predation cues usually reduced browsing on surfaces in late-stage larvae, but contrary to prediction, resulted in neither significantly greater production of adult mosquitoes nor significantly greater estimated rate of increase. Thus we have strong evidence that timing of mortality contributes to overcompensation and the Hydra effect in mosquitoes. Evidence that predation cues alone can result in overcompensation via prudent resource exploitation is lacking. We expect the overcompensation in response to early mortality will be common in organisms with complex life cycles, density dependence among juveniles, and developmental control of populations. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

A comprehensive energy approach to predict fatigue life in CuAlBe shape memory alloy

NASA Astrophysics Data System (ADS)

Sameallah, S.; Legrand, V.; Saint-Sulpice, L.; Kadkhodaei, M.; Arbab Chirani, S.

2015-02-01

Stabilized dissipated energy is an effective parameter on the fatigue life of shape memory alloys (SMAs). In this study, a formula is proposed to directly evaluate the stabilized dissipated energy for different values of the maximum and minimum applied stresses, as well as the loading frequency, under cyclic tensile loadings. To this aim, a one-dimensional fully coupled thermomechanical constitutive model and a cycle-dependent phase diagram are employed to predict the uniaxial stress-strain response of an SMA in a specified cycle, including the stabilized one, with no need of obtaining the responses of the previous cycles. An enhanced phase diagram in which different slopes are defined for the start and finish of a backward transformation strip is also proposed to enable the capture of gradual transformations in a CuAlBe shape memory alloy. It is shown that the present approach is capable of reproducing the experimental responses of CuAlBe specimens under cyclic tensile loadings. An explicit formula is further presented to predict the fatigue life of CuAlBe as a function of the maximum and minimum applied stresses as well as the loading frequency. Fatigue tests are also carried out, and this formula is verified against the empirically predicted number of cycles for failure.

Ceramic Matrix Composites (CMC) Life Prediction Method Development

NASA Technical Reports Server (NTRS)

Levine, Stanley R.; Calomino, Anthony M.; Ellis, John R.; Halbig, Michael C.; Mital, Subodh K.; Murthy, Pappu L.; Opila, Elizabeth J.; Thomas, David J.; Thomas-Ogbuji, Linus U.; Verrilli, Michael J.

2000-01-01

Advanced launch systems (e.g., Reusable Launch Vehicle and other Shuttle Class concepts, Rocket-Based Combine Cycle, etc.), and interplanetary vehicles will very likely incorporate fiber reinforced ceramic matrix composites (CMC) in critical propulsion components. The use of CMC is highly desirable to save weight, to improve reuse capability, and to increase performance. CMC candidate applications are mission and cycle dependent and may include turbopump rotors, housings, combustors, nozzle injectors, exit cones or ramps, and throats. For reusable and single mission uses, accurate prediction of life is critical to mission success. The tools to accomplish life prediction are very immature and not oriented toward the behavior of carbon fiber reinforced silicon carbide (C/SiC), the primary system of interest for a variety of space propulsion applications. This paper describes an approach to satisfy the need to develop an integrated life prediction system for CMC that addresses mechanical durability due to cyclic and steady thermomechanical loads, and takes into account the impact of environmental degradation.

Life cycle monitoring of lithium-ion polymer batteries using cost-effective thermal infrared sensors with applications for lifetime prediction

NASA Astrophysics Data System (ADS)

Zhou, Xunfei; Malik, Anav; Hsieh, Sheng-Jen

2017-05-01

Lithium-ion batteries have become indispensable parts of our lives for their high-energy density and long lifespan. However, failure due to from abusive usage conditions, flawed manufacturing processes, and aging and adversely affect battery performance and even endanger people and property. Therefore, battery cells that are failing or reaching their end-of-life need to be replaced. Traditionally, battery lifetime prediction is achieved by analyzing data from current, voltage and impedance sensors. However, such a prognostic system is expensive to implement and requires direct contact. In this study, low-cost thermal infrared sensors were used to acquire thermographic images throughout the entire lifetime of small scale lithium-ion polymer batteries (410 cycles). The infrared system (non-destructive) took temperature readings from multiple batteries during charging and discharging cycles of 1C. Thermal characteristics of the batteries were derived from the thermographic images. A time-dependent and spatially resolved temperature mapping was obtained and quantitatively analyzed. The developed model can predict cycle number using the first 10 minutes of surface temperature data acquired through infrared imaging at the beginning of the cycle, with an average error rate of less than 10%. This approach can be used to correlate thermal characteristics of the batteries with life cycles, and to propose cost-effective thermal infrared imaging applications in battery prognostic systems.

A Combined High and Low Cycle Fatigue Model for Life Prediction of Turbine Blades

PubMed Central

Yue, Peng; Yu, Zheng-Yong; Wang, Qingyuan

2017-01-01

Combined high and low cycle fatigue (CCF) generally induces the failure of aircraft gas turbine attachments. Based on the aero-engine load spectrum, accurate assessment of fatigue damage due to the interaction of high cycle fatigue (HCF) resulting from high frequency vibrations and low cycle fatigue (LCF) from ground-air-ground engine cycles is of critical importance for ensuring structural integrity of engine components, like turbine blades. In this paper, the influence of combined damage accumulation on the expected CCF life are investigated for turbine blades. The CCF behavior of a turbine blade is usually studied by testing with four load-controlled parameters, including high cycle stress amplitude and frequency, and low cycle stress amplitude and frequency. According to this, a new damage accumulation model is proposed based on Miner’s rule to consider the coupled damage due to HCF-LCF interaction by introducing the four load parameters. Five experimental datasets of turbine blade alloys and turbine blades were introduced for model validation and comparison between the proposed Miner, Manson-Halford, and Trufyakov-Kovalchuk models. Results show that the proposed model provides more accurate predictions than others with lower mean and standard deviation values of model prediction errors. PMID:28773064

A Combined High and Low Cycle Fatigue Model for Life Prediction of Turbine Blades.

PubMed

Zhu, Shun-Peng; Yue, Peng; Yu, Zheng-Yong; Wang, Qingyuan

2017-06-26

Combined high and low cycle fatigue (CCF) generally induces the failure of aircraft gas turbine attachments. Based on the aero-engine load spectrum, accurate assessment of fatigue damage due to the interaction of high cycle fatigue (HCF) resulting from high frequency vibrations and low cycle fatigue (LCF) from ground-air-ground engine cycles is of critical importance for ensuring structural integrity of engine components, like turbine blades. In this paper, the influence of combined damage accumulation on the expected CCF life are investigated for turbine blades. The CCF behavior of a turbine blade is usually studied by testing with four load-controlled parameters, including high cycle stress amplitude and frequency, and low cycle stress amplitude and frequency. According to this, a new damage accumulation model is proposed based on Miner's rule to consider the coupled damage due to HCF-LCF interaction by introducing the four load parameters. Five experimental datasets of turbine blade alloys and turbine blades were introduced for model validation and comparison between the proposed Miner, Manson-Halford, and Trufyakov-Kovalchuk models. Results show that the proposed model provides more accurate predictions than others with lower mean and standard deviation values of model prediction errors.

Effects of complex life cycles on genetic diversity: cyclical parthenogenesis.

PubMed

Rouger, R; Reichel, K; Malrieu, F; Masson, J P; Stoeckel, S

2016-11-01

Neutral patterns of population genetic diversity in species with complex life cycles are difficult to anticipate. Cyclical parthenogenesis (CP), in which organisms undergo several rounds of clonal reproduction followed by a sexual event, is one such life cycle. Many species, including crop pests (aphids), human parasites (trematodes) or models used in evolutionary science (Daphnia), are cyclical parthenogens. It is therefore crucial to understand the impact of such a life cycle on neutral genetic diversity. In this paper, we describe distributions of genetic diversity under conditions of CP with various clonal phase lengths. Using a Markov chain model of CP for a single locus and individual-based simulations for two loci, our analysis first demonstrates that strong departures from full sexuality are observed after only a few generations of clonality. The convergence towards predictions made under conditions of full clonality during the clonal phase depends on the balance between mutations and genetic drift. Second, the sexual event of CP usually resets the genetic diversity at a single locus towards predictions made under full sexuality. However, this single recombination event is insufficient to reshuffle gametic phases towards full-sexuality predictions. Finally, for similar levels of clonality, CP and acyclic partial clonality (wherein a fixed proportion of individuals are clonally produced within each generation) differentially affect the distribution of genetic diversity. Overall, this work provides solid predictions of neutral genetic diversity that may serve as a null model in detecting the action of common evolutionary or demographic processes in cyclical parthenogens (for example, selection or bottlenecks).

Live Fast, Die Young: Experimental Evidence of Population Extinction Risk due to Climate Change.

PubMed

Bestion, Elvire; Teyssier, Aimeric; Richard, Murielle; Clobert, Jean; Cote, Julien

2015-10-01

Evidence has accumulated in recent decades on the drastic impact of climate change on biodiversity. Warming temperatures have induced changes in species physiology, phenology, and have decreased body size. Such modifications can impact population dynamics and could lead to changes in life cycle and demography. More specifically, conceptual frameworks predict that global warming will severely threaten tropical ectotherms while temperate ectotherms should resist or even benefit from higher temperatures. However, experimental studies measuring the impacts of future warming trends on temperate ectotherms' life cycle and population persistence are lacking. Here we investigate the impacts of future climates on a model vertebrate ectotherm species using a large-scale warming experiment. We manipulated climatic conditions in 18 seminatural populations over two years to obtain a present climate treatment and a warm climate treatment matching IPCC predictions for future climate. Warmer temperatures caused a faster body growth, an earlier reproductive onset, and an increased voltinism, leading to a highly accelerated life cycle but also to a decrease in adult survival. A matrix population model predicts that warm climate populations in our experiment should go extinct in around 20 y. Comparing our experimental climatic conditions to conditions encountered by populations across Europe, we suggest that warming climates should threaten a significant number of populations at the southern range of the distribution. Our findings stress the importance of experimental approaches on the entire life cycle to more accurately predict population and species persistence in future climates.

Live Fast, Die Young: Experimental Evidence of Population Extinction Risk due to Climate Change

PubMed Central

Bestion, Elvire; Teyssier, Aimeric; Richard, Murielle; Clobert, Jean; Cote, Julien

2015-01-01

Evidence has accumulated in recent decades on the drastic impact of climate change on biodiversity. Warming temperatures have induced changes in species physiology, phenology, and have decreased body size. Such modifications can impact population dynamics and could lead to changes in life cycle and demography. More specifically, conceptual frameworks predict that global warming will severely threaten tropical ectotherms while temperate ectotherms should resist or even benefit from higher temperatures. However, experimental studies measuring the impacts of future warming trends on temperate ectotherms' life cycle and population persistence are lacking. Here we investigate the impacts of future climates on a model vertebrate ectotherm species using a large-scale warming experiment. We manipulated climatic conditions in 18 seminatural populations over two years to obtain a present climate treatment and a warm climate treatment matching IPCC predictions for future climate. Warmer temperatures caused a faster body growth, an earlier reproductive onset, and an increased voltinism, leading to a highly accelerated life cycle but also to a decrease in adult survival. A matrix population model predicts that warm climate populations in our experiment should go extinct in around 20 y. Comparing our experimental climatic conditions to conditions encountered by populations across Europe, we suggest that warming climates should threaten a significant number of populations at the southern range of the distribution. Our findings stress the importance of experimental approaches on the entire life cycle to more accurately predict population and species persistence in future climates. PMID:26501958

Experimental and modeling results of creep fatigue life of Inconel 617 and Haynes 230 at 850 C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xiang; Sokolov, Mikhail A; Sham, Sam

Creep fatigue testing of Ni-based superalloy Inconel 617 and Haynes 230 were conducted in the air at 850 C. Tests were performed with fully reversed axial strain control at a total strain range of 0.5%, 1.0% or 1.5% and hold time at maximum tensile strain for 3, 10 or 30 min. In addition, two creep fatigue life prediction methods, i.e. linear damage summation and frequency-modified tensile hysteresis energy modeling, were evaluated and compared with experimental results. Under all creep fatigue tests, Haynes 230 performed better than Inconel 617. Compared to the low cycle fatigue life, the cycles to failure formore » both materials decreased under creep fatigue test conditions. Longer hold time at maximum tensile strain would cause a further reduction in both material creep fatigue life. The linear damage summation could predict the creep fatigue life of Inconel 617 for limited test conditions, but considerably underestimated the creep fatigue life of Haynes 230. In contrast, frequency-modified tensile hysteresis energy modeling showed promising creep fatigue life prediction results for both materials.« less

Experimental and modeling results of creep-fatigue life of Inconel 617 and Haynes 230 at 850 °C

NASA Astrophysics Data System (ADS)

Chen, Xiang; Sokolov, Mikhail A.; Sham, Sam; Erdman, Donald L., III; Busby, Jeremy T.; Mo, Kun; Stubbins, James F.

2013-01-01

Creep-fatigue testing of Ni-based superalloy Inconel 617 and Haynes 230 were conducted in the air at 850 °C. Tests were performed with fully reversed axial strain control at a total strain range of 0.5%, 1.0% or 1.5% and hold time at maximum tensile strain for 3, 10 or 30 min. In addition, two creep-fatigue life prediction methods, i.e. linear damage summation and frequency-modified tensile hysteresis energy modeling, were evaluated and compared with experimental results. Under all creep-fatigue tests, Haynes 230 performed better than Inconel 617. Compared to the low cycle fatigue life, the cycles to failure for both materials decreased under creep-fatigue test conditions. Longer hold time at maximum tensile strain would cause a further reduction in both material creep-fatigue life. The linear damage summation could predict the creep-fatigue life of Inconel 617 for limited test conditions, but considerably underestimated the creep-fatigue life of Haynes 230. In contrast, frequency-modified tensile hysteresis energy modeling showed promising creep-fatigue life prediction results for both materials.

Weibull-Based Design Methodology for Rotating Aircraft Engine Structures

NASA Technical Reports Server (NTRS)

Zaretsky, Erwin; Hendricks, Robert C.; Soditus, Sherry

2002-01-01

The NASA Energy Efficient Engine (E(sup 3)-Engine) is used as the basis of a Weibull-based life and reliability analysis. Each component's life and thus the engine's life is defined by high-cycle fatigue (HCF) or low-cycle fatigue (LCF). Knowing the cumulative life distribution of each of the components making up the engine as represented by a Weibull slope is a prerequisite to predicting the life and reliability of the entire engine. As the engine Weibull slope increases, the predicted lives decrease. The predicted engine lives L(sub 5) (95 % probability of survival) of approximately 17,000 and 32,000 hr do correlate with current engine maintenance practices without and with refurbishment. respectively. The individual high pressure turbine (HPT) blade lives necessary to obtain a blade system life L(sub 0.1) (99.9 % probability of survival) of 9000 hr for Weibull slopes of 3, 6 and 9, are 47,391 and 20,652 and 15,658 hr, respectively. For a design life of the HPT disks having probable points of failure equal to or greater than 36,000 hr at a probability of survival of 99.9 %, the predicted disk system life L(sub 0.1) can vary from 9,408 to 24,911 hr.

Low-cycle thermal fatigue

NASA Technical Reports Server (NTRS)

Halford, G. R.

1986-01-01

A state-of-the-art review is presented of the field of thermal fatigue. Following a brief historical review, the concept is developed that thermal fatigue can be viewed as processes of unbalanced deformation and cracking. The unbalances refer to dissimilar mechanisms occurring in opposing halves of thermal fatigue loading and unloading cycles. Extensive data summaries are presented and results are interpreted in terms of the unbalanced processes involved. Both crack initiation and crack propagation results are summarized. Testing techniques are reviewed, and considerable discussion is given to a technique for thermal fatigue simulation, known as the bithermal fatigue test. Attention is given to the use of isothermal life prediction methods for the prediction of thermal fatigue lives. Shortcomings of isothermally-based life prediction methods are pointed out. Several examples of analyses and thermal fatigue life predictions of high technology structural components are presented. Finally, numerous dos and don'ts relative to design against thermal fatigue are presented.

Investigation of Cumulative Fatigue Damage Through Sequential Low Cycle Fatigue and High Cycle Fatigue Cycling at High Temperature for a Type 316LN Stainless Steel: Life-Prediction Techniques and Associated Mechanisms

NASA Astrophysics Data System (ADS)

Sarkar, Aritra; Nagesha, A.; Parameswaran, P.; Sandhya, R.; Laha, K.; Okazaki, M.

2017-03-01

Cumulative fatigue damage under sequential low cycle fatigue (LCF) and high cycle fatigue (HCF) cycling was investigated at 923 K (650 °C) by conducting HCF tests on specimens subjected to prior LCF cycling at various strain amplitudes. Remnant HCF lives were found to decrease drastically with increase in prior fatigue exposure as a result of strong LCF-HCF interactions. The rate of decrease in remnant lives varied as a function of the applied strain amplitude. A threshold damage in terms of prior LCF life-fraction was found, below which no significant LCF-HCF interaction takes place. Similarly, a critical damage during the LCF pre-cycling marking the highest degree of LCF-HCF interaction was identified which was found to depend on the applied strain amplitude. In view of the non-linear damage accumulation behavior, Miner's linear damage rule proved to be highly non-conservative. Manson's damage curve approach, suitably modified, was found to be a better alternative for predicting the remnant HCF life. The single constant ( β) employed in the model, which reflects the damage accumulation of the material under two/multi-level loading conditions is derived from the regression analysis of the experimental results and validated further.

Semi-empirical long-term cycle life model coupled with an electrolyte depletion function for large-format graphite/LiFePO4 lithium-ion batteries

NASA Astrophysics Data System (ADS)

Park, Joonam; Appiah, Williams Agyei; Byun, Seoungwoo; Jin, Dahee; Ryou, Myung-Hyun; Lee, Yong Min

2017-10-01

To overcome the limitation of simple empirical cycle life models based on only equivalent circuits, we attempt to couple a conventional empirical capacity loss model with Newman's porous composite electrode model, which contains both electrochemical reaction kinetics and material/charge balances. In addition, an electrolyte depletion function is newly introduced to simulate a sudden capacity drop at the end of cycling, which is frequently observed in real lithium-ion batteries (LIBs). When simulated electrochemical properties are compared with experimental data obtained with 20 Ah-level graphite/LiFePO4 LIB cells, our semi-empirical model is sufficiently accurate to predict a voltage profile having a low standard deviation of 0.0035 V, even at 5C. Additionally, our model can provide broad cycle life color maps under different c-rate and depth-of-discharge operating conditions. Thus, this semi-empirical model with an electrolyte depletion function will be a promising platform to predict long-term cycle lives of large-format LIB cells under various operating conditions.

A model for life predictions of nickel-base superalloys in high-temperature low cycle fatigue

NASA Technical Reports Server (NTRS)

Romanoski, Glenn R.; Pelloux, Regis M.; Antolovich, Stephen D.

1988-01-01

Extensive characterization of low-cycle fatigue damage mechanisms was performed on polycrystalline Rene 80 and IN100 tested in the temperature range from 871 to 1000 C. Low-cycle fatigue life was found to be dominated by propagation of microcracks to a critical size governed by the maximum tensile stress. A model was developed which incorporates a threshold stress for crack extension, a stress-based crack growth expression, and a failure criterion. The mathematical equivalence between this mechanistically based model and the strain-life low-cycle fatigue law was demonstrated using cyclic stress-strain relationships. The model was shown to correlate the high-temperature low-cycle fatigue data of the different nickel-base superalloys considered in this study.

Strainrange partitioning behavior of an automotive turbine alloy

NASA Technical Reports Server (NTRS)

Annis, C. G.; Vanwanderham, M. C.; Wallace, R. M.

1976-01-01

This report addresses Strainrange Partitioning, an advanced life prediction analysis procedure, as applied to CA-101 (cast IN 792 + Hf), an alloy proposed for turbine disks in automotive gas turbine engines. The methodology was successful in predicting specimen life under thermal-mechanical cycling, to within a factor of + or - 2.

Evolution and maintenance of haploid-diploid life cycles in natural populations: The case of the marine brown alga Ectocarpus.

PubMed

Couceiro, Lucía; Le Gac, Mickael; Hunsperger, Heather M; Mauger, Stéphane; Destombe, Christophe; Cock, J Mark; Ahmed, Sophia; Coelho, Susana M; Valero, Myriam; Peters, Akira F

2015-07-01

The evolutionary stability of haploid-diploid life cycles is still controversial. Mathematical models indicate that niche differences between ploidy phases may be a necessary condition for the evolution and maintenance of these life cycles. Nevertheless, experimental support for this prediction remains elusive. In the present work, we explored this hypothesis in natural populations of the brown alga Ectocarpus. Consistent with the life cycle described in culture, Ectocarpus crouaniorum in NW France and E. siliculosus in SW Italy exhibited an alternation between haploid gametophytes and diploid sporophytes. Our field data invalidated, however, the long-standing view of an isomorphic alternation of generations. Gametophytes and sporophytes displayed marked differences in size and, conforming to theoretical predictions, occupied different spatiotemporal niches. Gametophytes were found almost exclusively on the alga Scytosiphon lomentaria during spring whereas sporophytes were present year-round on abiotic substrata. Paradoxically, E. siliculosus in NW France exhibited similar habitat usage despite the absence of alternation of ploidy phases. Diploid sporophytes grew both epilithically and epiphytically, and this mainly asexual population gained the same ecological advantage postulated for haploid-diploid populations. Consequently, an ecological interpretation of the niche differences between haploid and diploid individuals does not seem to satisfactorily explain the evolution of the Ectocarpus life cycle. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Incorporation of Half-Cycle Theory Into Ko Aging Theory for Aerostructural Flight-Life Predictions

NASA Technical Reports Server (NTRS)

Ko, William L.; Tran, Van T.; Chen, Tony

2007-01-01

The half-cycle crack growth theory was incorporated into the Ko closed-form aging theory to improve accuracy in the predictions of operational flight life of failure-critical aerostructural components. A new crack growth computer program was written for reading the maximum and minimum loads of each half-cycle from the random loading spectra for crack growth calculations and generation of in-flight crack growth curves. The unified theories were then applied to calculate the number of flights (operational life) permitted for B-52B pylon hooks and Pegasus adapter pylon hooks to carry the Hyper-X launching vehicle that air launches the X-43 Hyper-X research vehicle. A crack growth curve for each hook was generated for visual observation of the crack growth behavior during the entire air-launching or captive flight. It was found that taxiing and the takeoff run induced a major portion of the total crack growth per flight. The operational life theory presented can be applied to estimate the service life of any failure-critical structural components.

Isothermal life prediction of composite lamina using a damage mechanics approach

NASA Technical Reports Server (NTRS)

Abuelfoutouh, Nader M.; Verrilli, Michael J.; Halford, Gary R.

1989-01-01

A method for predicting isothermal plastic fatigue life of a composite lamina is presented in which both fibers and matrix are isotropic materials. In general, the fatigue resistances of the matrix, fibers, and interfacial material must be known in order to predict composite fatigue life. Composite fatigue life is predicted using only the matrix fatigue resistance due to inelasticity micromechanisms. The effect of the fiber orientation on loading direction is accounted for while predicting composite life. The application is currently limited to isothermal cases where the internal thermal stresses that might arise from thermal strain mismatch between fibers and matrix are negligible. The theory is formulated to predict the fatigue life of a composite lamina under either load or strain control. It is applied currently to predict the life of tungsten-copper composite lamina at 260 C under tension-tension load control. The calculated life of the lamina is in good agreement with available composite low cycle fatigue data.

Metallic positive expulsion diaphragms

NASA Technical Reports Server (NTRS)

Gleich, D.

1972-01-01

High-cycle life ring-reinforced hemispherical type positive expulsion diaphragm performance was demonstrated by room temperature fluid expulsion tests of 13" diameter, 8 mil thick stainless steel configurations. A maximum of eleven (11) leak-free, fluid expulsions were achieved by a 25 deg cone angle diaphragm hoop-reinforced with .110-inch cross-sectional diameter wires. This represents a 70% improvement in diaphragm reversal cycle life compared to results previously obtained. The reversal tests confirmed analytic predictions for diaphragm cycle life increases due to increasing values of diaphragm cone angle, radius to thickness ratio and material strain to necking capacity. Practical fabrication techniques were demonstrated for forming close-tolerance, thin corrugated shells and for obtaining closely controlled reinforcing ring stiffness required to maximize diaphragm cycle life. A non-destructive inspection technique for monitoring large local shell bending strains was developed.

The Effect of Drive Signal Limiting on High Cycle Fatigue Life Analysis

NASA Technical Reports Server (NTRS)

Kihm, Frederic; Rizzi, Stephen A.

2014-01-01

It is common practice to assume a Gaussian distribution of both the input acceleration and the response when modeling random vibration tests. In the laboratory, however, shaker controllers often limit the drive signal to prevent high amplitude peaks. The high amplitudes may either be truncated at a given level (socalled brick wall limiting or abrupt clipping), or compressed (soft limiting), resulting in drive signals which are no longer Gaussian. The paper first introduces several methods for limiting a drive signal, including brick wall limiting and compression. The limited signal is then passed through a linear time-invariant system representing a device under test. High cycle fatigue life predictions are subsequently made using spectral fatigue and rainflow cycle counting schemes. The life predictions are compared with those obtained from unclipped input signals. Some guidelines are provided to help the test engineer decide how clipping should be applied under different test scenarios.

Effects of complex life cycles on genetic diversity: cyclical parthenogenesis

PubMed Central

Rouger, R; Reichel, K; Malrieu, F; Masson, J P; Stoeckel, S

2016-01-01

Neutral patterns of population genetic diversity in species with complex life cycles are difficult to anticipate. Cyclical parthenogenesis (CP), in which organisms undergo several rounds of clonal reproduction followed by a sexual event, is one such life cycle. Many species, including crop pests (aphids), human parasites (trematodes) or models used in evolutionary science (Daphnia), are cyclical parthenogens. It is therefore crucial to understand the impact of such a life cycle on neutral genetic diversity. In this paper, we describe distributions of genetic diversity under conditions of CP with various clonal phase lengths. Using a Markov chain model of CP for a single locus and individual-based simulations for two loci, our analysis first demonstrates that strong departures from full sexuality are observed after only a few generations of clonality. The convergence towards predictions made under conditions of full clonality during the clonal phase depends on the balance between mutations and genetic drift. Second, the sexual event of CP usually resets the genetic diversity at a single locus towards predictions made under full sexuality. However, this single recombination event is insufficient to reshuffle gametic phases towards full-sexuality predictions. Finally, for similar levels of clonality, CP and acyclic partial clonality (wherein a fixed proportion of individuals are clonally produced within each generation) differentially affect the distribution of genetic diversity. Overall, this work provides solid predictions of neutral genetic diversity that may serve as a null model in detecting the action of common evolutionary or demographic processes in cyclical parthenogens (for example, selection or bottlenecks). PMID:27436524

Compositional shifts in root-associated bacterial and archaeal microbiota track the plant life cycle in field-grown rice

PubMed Central

Edwards, Joseph A.; Santos-Medellín, Christian M.; Liechty, Zachary S.; Nguyen, Bao; Lurie, Eugene; Eason, Shane; Phillips, Gregory

2018-01-01

Bacterial communities associated with roots impact the health and nutrition of the host plant. The dynamics of these microbial assemblies over the plant life cycle are, however, not well understood. Here, we use dense temporal sampling of 1,510 samples from root spatial compartments to characterize the bacterial and archaeal components of the root-associated microbiota of field grown rice (Oryza sativa) over the course of 3 consecutive growing seasons, as well as 2 sites in diverse geographic regions. The root microbiota was found to be highly dynamic during the vegetative phase of plant growth and then stabilized compositionally for the remainder of the life cycle. Bacterial and archaeal taxa conserved between field sites were defined as predictive features of rice plant age by modeling using a random forest approach. The age-prediction models revealed that drought-stressed plants have developmentally immature microbiota compared to unstressed plants. Further, by using genotypes with varying developmental rates, we show that shifts in the microbiome are correlated with rates of developmental transitions rather than age alone, such that different microbiota compositions reflect juvenile and adult life stages. These results suggest a model for successional dynamics of the root-associated microbiota over the plant life cycle. PMID:29474469

Compositional shifts in root-associated bacterial and archaeal microbiota track the plant life cycle in field-grown rice.

PubMed

Edwards, Joseph A; Santos-Medellín, Christian M; Liechty, Zachary S; Nguyen, Bao; Lurie, Eugene; Eason, Shane; Phillips, Gregory; Sundaresan, Venkatesan

2018-02-01

Bacterial communities associated with roots impact the health and nutrition of the host plant. The dynamics of these microbial assemblies over the plant life cycle are, however, not well understood. Here, we use dense temporal sampling of 1,510 samples from root spatial compartments to characterize the bacterial and archaeal components of the root-associated microbiota of field grown rice (Oryza sativa) over the course of 3 consecutive growing seasons, as well as 2 sites in diverse geographic regions. The root microbiota was found to be highly dynamic during the vegetative phase of plant growth and then stabilized compositionally for the remainder of the life cycle. Bacterial and archaeal taxa conserved between field sites were defined as predictive features of rice plant age by modeling using a random forest approach. The age-prediction models revealed that drought-stressed plants have developmentally immature microbiota compared to unstressed plants. Further, by using genotypes with varying developmental rates, we show that shifts in the microbiome are correlated with rates of developmental transitions rather than age alone, such that different microbiota compositions reflect juvenile and adult life stages. These results suggest a model for successional dynamics of the root-associated microbiota over the plant life cycle.

Multiaxial Fatigue Life Prediction Based on Short Crack Propagation Model with Equivalent Strain Parameter

NASA Astrophysics Data System (ADS)

Zhao, Xiang-Feng; Shang, De-Guang; Sun, Yu-Juan; Song, Ming-Liang; Wang, Xiao-Wei

2018-01-01

The maximum shear strain and the normal strain excursion on the critical plane are regarded as the primary parameters of the crack driving force to establish a new short crack model in this paper. An equivalent strain-based intensity factor is proposed to correlate the short crack growth rate under multiaxial loading. According to the short crack model, a new method is proposed for multiaxial fatigue life prediction based on crack growth analysis. It is demonstrated that the method can be used under proportional and non-proportional loadings. The predicted results showed a good agreement with experimental lives in both high-cycle and low-cycle regions.

Technical evaluation report of the Specialists Meeting on Characterization of Low Cycle High Temperature Fatigue by the Strainrange Partitioning Method

NASA Technical Reports Server (NTRS)

Drapier, J. M.; Hirschberg, M. H.

1979-01-01

The ability of the Strainrange Partitioning Method SRP was evaluated to correlate the creep-fatigue behavior of gas turbine materials and to predict the creep fatigue life of laboratory specimens subjected to complex cycling conditions. A reference body of high temperature creep fatigue data which can be used in the evaluation of other SRP and low cycle high temperature fatigue predictive techniques was provided.

A Satellite View of Global Water and Energy Cycling

NASA Astrophysics Data System (ADS)

Houser, P. R.

2012-12-01

The global water cycle describes liquid, solid and vapor water dynamics as it moves through the atmosphere, oceans and land. Life exists because of water, and civilization depends on adapting to the constraints imposed by water availability. The carbon, water and energy cycles are strongly interdependent - energy is moved through evaporation and condensation, and photosynthesis is closely related to transpiration. There are significant knowledge gaps about water storage, fluxes and dynamics - we currently do not really know how much water is stored in snowpacks, groundwater or reservoirs. The view from space offers a vision for water science advancement. This vision includes observation, understanding, and prediction advancements that will improve water management and to inform water-related infrastructure that planning to provide for human needs and to protect the natural environment. The water cycle science challenge is to deploy a series of coordinated earth observation satellites, and to integrate in situ and space-borne observations to quantify the key water-cycle state variables and fluxes. The accompanying societal challenge is to integrate this information along with water cycle physics, and ecosystems and societal considerations as a basis for enlightened water resource management and to protect life and property from effects of water cycle extremes. Better regional to global scale water-cycle observations and predictions need to be readily available to reduce loss of life and property caused by water-related hazards. To this end, the NASA Energy and Water cycle Study (NEWS) has been documenting the satellite view of the water cycle with a goal of enabling improved, observationally based, predictions of water and energy cycle consequences of Earth system variability and change. NEWS has fostered broad interdisciplinary collaborations to study experimental and operational satellite observations and has developed analysis tools for characterizing air/sea fluxes, ocean circulation, atmospheric states, radiative balances, land surface states, sub-surface hydrology, snow and ice. This presentation will feature an overview of recent progress towards this challenge, and lay out the plan for coordination with complementary international efforts.

Analysis of Ageing Effect on Li-Polymer Batteries

PubMed Central

Barcellona, Simone; Brenna, Morris; Foiadelli, Federica; Longo, Michela; Piegari, Luigi

2015-01-01

Lithium-ion batteries are a key technology for current and future energy storage in mobile and stationary application. In particular, they play an important role in the electrification of mobility and therefore the battery lifetime prediction is a fundamental aspect for successful market introduction. Numerous studies developed ageing models capable of predicting battery life span. Most of the previous works compared the effect of the ageing factors to a battery's cycle life. These cycles are identical, which is not the case for electric vehicles applications. Indeed, most of the available information is based on results from laboratory testing, under very controlled environments, and using ageing protocols, which may not correctly reflect the actual utilization. For this reason, it is important to link the effect of duty cycles with the ageing of the batteries. This paper proposes a simple method to investigate the effect of the duty cycle on the batteries lifetime through tests performed on different cells for different kinds of cycle. In this way, a generic complex cycle can be seen as a composition of elemental cycles by means of Rainflow procedures. Consequently, the ageing due to any cycle can be estimated starting from the knowledge of simpler cycles. PMID:26236775

Thermal barrier coating life prediction model development

NASA Technical Reports Server (NTRS)

Sheffler, K. D.; Demasi, J. T.

1985-01-01

A methodology was established to predict thermal barrier coating life in an environment simulative of that experienced by gas turbine airfoils. Specifically, work is being conducted to determine failure modes of thermal barrier coatings in the aircraft engine environment. Analytical studies coupled with appropriate physical and mechanical property determinations are being employed to derive coating life prediction model(s) on the important failure mode(s). An initial review of experimental and flight service components indicates that the predominant mode of TBC failure involves thermomechanical spallation of the ceramic coating layer. This ceramic spallation involves the formation of a dominant crack in the ceramic coating parallel to and closely adjacent to the metal-ceramic interface. Initial results from a laboratory test program designed to study the influence of various driving forces such as temperature, thermal cycle frequency, environment, and coating thickness, on ceramic coating spalling life suggest that bond coat oxidation damage at the metal-ceramic interface contributes significantly to thermomechanical cracking in the ceramic layer. Low cycle rate furnace testing in air and in argon clearly shows a dramatic increase of spalling life in the non-oxidizing environments.

Aging Theories for Establishing Safe Life Spans of Airborne Critical Structural Components

NASA Technical Reports Server (NTRS)

Ko, William L.

2003-01-01

New aging theories have been developed to establish the safe life span of airborne critical structural components such as B-52B aircraft pylon hooks for carrying air-launch drop-test vehicles. The new aging theories use the equivalent-constant-amplitude loading spectrum to represent the actual random loading spectrum with the same damaging effect. The crack growth due to random loading cycling of the first flight is calculated using the half-cycle theory, and then extrapolated to all the crack growths of the subsequent flights. The predictions of the new aging theories (finite difference aging theory and closed-form aging theory) are compared with the classical flight-test life theory and the previously developed Ko first- and Ko second-order aging theories. The new aging theories predict the number of safe flights as considerably lower than that predicted by the classical aging theory, and slightly lower than those predicted by the Ko first- and Ko second-order aging theories due to the inclusion of all the higher order terms.

Interconnect fatigue design for terrestrial photovoltaic modules

NASA Technical Reports Server (NTRS)

Mon, G. R.; Moore, D. M.; Ross, R. G., Jr.

1982-01-01

The results of comprehensive investigation of interconnect fatigue that has led to the definition of useful reliability-design and life-prediction algorithms are presented. Experimental data indicate that the classical strain-cycle (fatigue) curve for the interconnect material is a good model of mean interconnect fatigue performance, but it fails to account for the broad statistical scatter, which is critical to reliability prediction. To fill this shortcoming the classical fatigue curve is combined with experimental cumulative interconnect failure rate data to yield statistical fatigue curves (having failure probability as a parameter) which enable (1) the prediction of cumulative interconnect failures during the design life of an array field, and (2) the unambiguous--ie., quantitative--interpretation of data from field-service qualification (accelerated thermal cycling) tests. Optimal interconnect cost-reliability design algorithms are derived based on minimizing the cost of energy over the design life of the array field.

Interconnect fatigue design for terrestrial photovoltaic modules

NASA Astrophysics Data System (ADS)

Mon, G. R.; Moore, D. M.; Ross, R. G., Jr.

1982-03-01

The results of comprehensive investigation of interconnect fatigue that has led to the definition of useful reliability-design and life-prediction algorithms are presented. Experimental data indicate that the classical strain-cycle (fatigue) curve for the interconnect material is a good model of mean interconnect fatigue performance, but it fails to account for the broad statistical scatter, which is critical to reliability prediction. To fill this shortcoming the classical fatigue curve is combined with experimental cumulative interconnect failure rate data to yield statistical fatigue curves (having failure probability as a parameter) which enable (1) the prediction of cumulative interconnect failures during the design life of an array field, and (2) the unambiguous--ie., quantitative--interpretation of data from field-service qualification (accelerated thermal cycling) tests. Optimal interconnect cost-reliability design algorithms are derived based on minimizing the cost of energy over the design life of the array field.

A Darwinian approach to the origin of life cycles with group properties.

PubMed

Rashidi, Armin; Shelton, Deborah E; Michod, Richard E

2015-06-01

A selective explanation for the evolution of multicellular organisms from unicellular ones requires knowledge of both selective pressures and factors affecting the response to selection. Understanding the response to selection is particularly challenging in the case of evolutionary transitions in individuality, because these transitions involve a shift in the very units of selection. We develop a conceptual framework in which three fundamental processes (growth, division, and splitting) are the scaffold for unicellular and multicellular life cycles alike. We (i) enumerate the possible ways in which these processes can be linked to create more complex life cycles, (ii) introduce three genes based on growth, division and splitting that, acting in concert, determine the architecture of the life cycles, and finally, (iii) study the evolution of the simplest five life cycles using a heuristic model of coupled ordinary differential equations in which mutations are allowed in the three genes. We demonstrate how changes in the regulation of three fundamental aspects of colonial form (cell size, colony size, and colony cell number) could lead unicellular life cycles to evolve into primitive multicellular life cycles with group properties. One interesting prediction of the model is that selection generally favors cycles with group level properties when intermediate body size is associated with lowest mortality. That is, a universal requirement for the evolution of group cycles in the model is that the size-mortality curve be U-shaped. Furthermore, growth must decelerate with size. Copyright © 2015 Elsevier Inc. All rights reserved.

Life prediction and reliability assessment of lithium secondary batteries

NASA Astrophysics Data System (ADS)

Eom, Seung-Wook; Kim, Min-Kyu; Kim, Ick-Jun; Moon, Seong-In; Sun, Yang-Kook; Kim, Hyun-Soo

Reliability assessment of lithium secondary batteries was mainly considered. Shape parameter (β) and scale parameter (η) were calculated from experimental data based on cycle life test. We also examined safety characteristics of lithium secondary batteries. As proposed by IEC 62133 (2002), we had performed all of the safety/abuse tests such as 'mechanical abuse tests', 'environmental abuse tests', 'electrical abuse tests'. This paper describes the cycle life of lithium secondary batteries, FMEA (failure modes and effects analysis) and the safety/abuse tests we had performed.

A high temperature fatigue life prediction computer code based on the total strain version of StrainRange Partitioning (SRP)

NASA Technical Reports Server (NTRS)

Mcgaw, Michael A.; Saltsman, James F.

1993-01-01

A recently developed high-temperature fatigue life prediction computer code is presented and an example of its usage given. The code discussed is based on the Total Strain version of Strainrange Partitioning (TS-SRP). Included in this code are procedures for characterizing the creep-fatigue durability behavior of an alloy according to TS-SRP guidelines and predicting cyclic life for complex cycle types for both isothermal and thermomechanical conditions. A reasonably extensive materials properties database is included with the code.

Grainex Mar-M 247 Turbine Disk Life Study for NASA's High Temperature High Speed Turbine Seal Test Facility

NASA Technical Reports Server (NTRS)

Delgado, Irebert R.

2015-01-01

An experimental and analytical fatigue life study was performed on the Grainex Mar-M 247 disk used in NASA s Turbine Seal Test Facility. To preclude fatigue cracks from growing to critical size in the NASA disk bolt holes due to cyclic loading at severe test conditions, a retirement-for-cause methodology was adopted to detect and monitor cracks within the bolt holes using eddy-current inspection. For the NASA disk material that was tested, the fatigue strain-life to crack initiation at a total strain of 0.5 percent, a minimum to maximum strain ratio of 0, and a bolt hole temperature of 649 C was calculated to be 665 cycles using -99.95 percent prediction intervals. The fatigue crack propagation life was calculated to be 367 cycles after implementing a safety factor of 2 on life. Thus, the NASA disk bolt hole total life or retirement life was determined to be 1032 cycles at a crack depth of 0.501 mm. An initial NASA disk bolt hole inspection at 665 cycles is suggested with 50 cycle inspection intervals thereafter to monitor fatigue crack growth.

Probabilistic Analysis of Aircraft Gas Turbine Disk Life and Reliability

NASA Technical Reports Server (NTRS)

Melis, Matthew E.; Zaretsky, Erwin V.; August, Richard

1999-01-01

Two series of low cycle fatigue (LCF) test data for two groups of different aircraft gas turbine engine compressor disk geometries were reanalyzed and compared using Weibull statistics. Both groups of disks were manufactured from titanium (Ti-6Al-4V) alloy. A NASA Glenn Research Center developed probabilistic computer code Probable Cause was used to predict disk life and reliability. A material-life factor A was determined for titanium (Ti-6Al-4V) alloy based upon fatigue disk data and successfully applied to predict the life of the disks as a function of speed. A comparison was made with the currently used life prediction method based upon crack growth rate. Applying an endurance limit to the computer code did not significantly affect the predicted lives under engine operating conditions. Failure location prediction correlates with those experimentally observed in the LCF tests. A reasonable correlation was obtained between the predicted disk lives using the Probable Cause code and a modified crack growth method for life prediction. Both methods slightly overpredict life for one disk group and significantly under predict it for the other.

Explicit prediction of hail using multimoment microphysics schemes for a hailstorm of 19 March 2014 in eastern China

NASA Astrophysics Data System (ADS)

Luo, Liping; Xue, Ming; Zhu, Kefeng; Zhou, Bowen

2017-07-01

In the late afternoon of 19 March 2014, a severe hailstorm swept through eastern central Zhejiang province, China. The storm produced golf ball-sized hail, strong winds, and lighting, lasting approximately 1 h over the coastal city of Taizhou. The Advanced Regional Prediction System is used to simulate the hailstorm using different configurations of the Milbrandt-Yau microphysics scheme that predict one, two, or three moments of the hydrometeor particle size distribution. Simulated fields, including accumulated precipitation and maximum estimated hail size (MESH), are verified against rain gauge observations and radar-derived MESH, respectively. For the case of the 19 March 2014 storms, the general evolution is better predicted with multimoment microphysics schemes than with the one-moment scheme; the three-moment scheme produces the best forecast. Predictions from the three-moment scheme qualitatively agree with observations in terms of size and amount of hail reaching the surface. The life cycle of the hailstorm is analyzed, using the most skillful, three-moment forecast. Based upon the tendency of surface hail mass flux, the hailstorm life cycle can be divided into three stages: developing, mature, and dissipating. Microphysical budget analyses are used to examine microphysical processes and characteristics during these three stages. The vertical structures within the storm and their link to environmental shear conditions are discussed; together with the rapid fall of hailstones, these structures and conditions appear to dictate this pulse storm's short life span. Finally, a conceptual model for the life cycle of pulse hailstorms is proposed.

High temperature low cycle fatigue mechanisms for nickel base and a copper base alloy. M.S. Thesis Final Report

NASA Technical Reports Server (NTRS)

Shih, C. I.

1982-01-01

Damage mechanisms were studied in Rene' 95 and NARloy Z, using optical, scanning and transmission in microscopy. In necklace Rene' 95, crack initiation was mainly associated with cracking of surface MC carbides, except for hold time tests at higher strain ranges where initiation was associated more with a grain boundary mechanism. A mixed mode of propagation with a faceted fracture morphology was typical for all cycle characters. The dependence of life on maximum tensile stress can be demonstrated by the data falling onto three lines corresponding to the three tensile hold times, in the life against maximum tensile stress plot. In NARloy Z, crack initiation was always at the grain boundaries. The mode of crack propagation depended on the cycle character. The life decreased with decreasing strain rate and with tensile holds. In terms of damage mode, different life prediction laws may be applicable to different cycle characters.

Evaluation program for secondary spacecraft cells

NASA Technical Reports Server (NTRS)

Christy, D. E.; Harkness, J. D.

1973-01-01

A life cycle test of secondary electric batteries for spacecraft applications was conducted. A sample number of nickel cadmium batteries were subjected to general performance tests to determine the limit of their actual capabilities. Weaknesses discovered in cell design are reported and aid in research and development efforts toward improving the reliability of spacecraft batteries. A statistical analysis of the life cycle prediction and cause of failure versus test conditions is provided.

PACS: acceptance test, quality control, warranty, and maintenance continuum

NASA Astrophysics Data System (ADS)

Romlein, John R.; Norton, Gary S.; Lyche, David K.; Richardson, Ronald R., Jr.

1999-07-01

As PACS gain greater acceptance and use in medical facilities the question of life cycle management must be addressed in terms that relate to the common business practices for medical information system and medical devices. The issues in life cycle management of such a system are relatively new to the industry. Increased use of PACS within the medical community requires that standardized life cycle management practices by developed and implemented. This paper develops a new of life cycle issues as cyclic and related events that are not only manageable, but also predictable in terms, of, frequency, duration data content, data exchange, potential outcomes, staffing requirement, documentation, and staff interaction. This view is presented as a continuum that begins at the acceptance testing of a PACS and continues throughout its life cycle. The continuum incorporates the required relationship between quality control testing and maintenance actions during warranty period and the maintenance years. Interrelated cyclic events are described that bind these processes together and provide a basis for long-term proactive management of PACS in a medical environment.

Benchmark notch test for life prediction

NASA Technical Reports Server (NTRS)

Domas, P. A.; Sharpe, W. N.; Ward, M.; Yau, J. F.

1982-01-01

The laser Interferometric Strain Displacement Gage (ISDG) was used to measure local strains in notched Inconel 718 test bars subjected to six different load histories at 649 C (1200 F) and including effects of tensile and compressive hold periods. The measurements were compared to simplified Neuber notch analysis predictions of notch root stress and strain. The actual strains incurred at the root of a discontinuity in cyclically loaded test samples subjected to inelastic deformation at high temperature where creep deformations readily occur were determined. The steady state cyclic, stress-strain response at the root of the discontinuity was analyzed. Flat, double notched uniaxially loaded fatigue specimens manufactured from the nickel base, superalloy Inconel 718 were used. The ISDG was used to obtain cycle by cycle recordings of notch root strain during continuous and hold time cycling at 649 C. Comparisons to Neuber and finite element model analyses were made. The results obtained provide a benchmark data set in high technology design where notch fatigue life is the predominant component service life limitation.

Evaluation of Inelastic Constitutive Models for Nonlinear Structural Analysis

NASA Technical Reports Server (NTRS)

Kaufman, A.

1983-01-01

The influence of inelastic material models on computed stress-strain states, and therefore predicted lives, was studied for thermomechanically loaded structures. Nonlinear structural analyses were performed on a fatigue specimen which was subjected to thermal cycling in fluidized beds and on a mechanically load cycled benchmark notch specimen. Four incremental plasticity creep models (isotropic, kinematic, combined isotropic-kinematic, combined plus transient creep) were exercised. Of the plasticity models, kinematic hardening gave results most consistent with experimental observations. Life predictions using the computed strain histories at the critical location with a Strainrange Partitioning approach considerably overpredicted the crack initiation life of the thermal fatigue specimen.

Survival analysis for customer satisfaction: A case study

NASA Astrophysics Data System (ADS)

Hadiyat, M. A.; Wahyudi, R. D.; Sari, Y.

2017-11-01

Most customer satisfaction surveys are conducted periodically to track their dynamics. One of the goals of this survey was to evaluate the service design by recognizing the trend of satisfaction score. Many researchers recommended in redesigning the service when the satisfaction scores were decreasing, so that the service life cycle could be predicted qualitatively. However, these scores were usually set in Likert scale and had quantitative properties. Thus, they should also be analyzed in quantitative model so that the predicted service life cycle would be done by applying the survival analysis. This paper discussed a starting point for customer satisfaction survival analysis with a case study in healthcare service.

High-temperature fatigue in metals - A brief review of life prediction methods developed at the Lewis Research Center of NASA

NASA Technical Reports Server (NTRS)

Halford, G. R.

1983-01-01

The presentation focuses primarily on the progress we at NASA Lewis Research Center have made. The understanding of the phenomenological processes of high temperature fatigue of metals for the purpose of calculating lives of turbine engine hot section components is discussed. Improved understanding resulted in the development of accurate and physically correct life prediction methods such as Strain-Range partitioning for calculating creep fatigue interactions and the Double Linear Damage Rule for predicting potentially severe interactions between high and low cycle fatigue. Examples of other life prediction methods are also discussed. Previously announced in STAR as A83-12159

Exploratory Thermal-mechanical Fatigue Results for Rene' 80 in Ultrahigh Vacuum

NASA Technical Reports Server (NTRS)

Sheinker, A. A.

1978-01-01

A limited study was conducted of the use of strainage partitioning for predicting the thermalmechanical fatigue life of cast nickel-base superalloy Rene' 80. The fatigue lives obtained by combined inphase thermal and mechanical strain cycling between 400 C (752 F) and 1000 C (1802 F) in an ultrahigh vacuum were considerably shorter than those represented by the four basic partitioned inelastic strainrange fatigue life relationships established previously for this alloy at 871 C (1600 F) and 1000 C (1832 F) in an ultrahigh vacuum. This behavior was attributed to the drastic decrease in ductility with decreasing temperature for this alloy. These results indicated that the prediction of the thermal-mechanical fatigue life of Rene' 80 by the method of strainrange partioning may be improved if based on the four basic fatigue life relationships determined at a lower temperature in the thermal-mechanical strain cycle.

A Predictive Framework for Thermomechanical Fatigue Life of High Silicon Molybdenum Ductile Cast Iron Based on Considerations of Strain Energy Dissipation

NASA Astrophysics Data System (ADS)

Avery, Katherine R.

Isothermal low cycle fatigue (LCF) and anisothermal thermomechanical fatigue (TMF) tests were conducted on a high silicon molybdenum (HiSiMo) cast iron for temperatures up to 1073K. LCF and out-of-phase (OP) TMF lives were significantly reduced when the temperature was near 673K due to an embrittlement phenomenon which decreases the ductility of HiSiMo at this temperature. In this case, intergranular fracture was predominant, and magnesium was observed at the fracture surface. When the thermal cycle did not include 673K, the failure mode was predominantly transgranular, and magnesium was not present on the fracture surface. The in-phase (IP) TMF lives were unaffected when the thermal cycle included 673K, and the predominant failure mode was found to be transgranular fracture, regardless of the temperature. No magnesium was present on the IP TMF fracture surfaces. Thus, the embrittlement phenomenon was found to contribute to fatigue damage only when the temperature was near 673K and a tensile stress was present. To account for the temperature- and stress-dependence of the embrittlement phenomenon on the TMF life of HiSiMo cast iron, an original model based on the cyclic inelastic energy dissipation is proposed which accounts for temperature-dependent differences in the rate of fatigue damage accumulation in tension and compression. The proposed model has few empirical parameters. Despite the simplicity of the model, the predicted fatigue life shows good agreement with more than 130 uniaxial low cycle and thermomechanical fatigue tests, cyclic creep tests, and tests conducted at slow strain rates and with hold times. The proposed model was implemented in a multiaxial formulation and applied to the fatigue life prediction of an exhaust manifold subjected to severe thermal cycles. The simulation results show good agreement with the failure locations and number of cycles to failure observed in a component-level experiment.

An Early Prediction of Sunspot Cycle 25

NASA Astrophysics Data System (ADS)

Nandy, D.; Bhowmik, P.

2017-12-01

The Sun's magnetic activity governs our space environment, creates space weather and impacts our technologies and climate. With increasing reliance on space- and ground-based technologies that are subject to space weather, the need to be able to forecast the future activity of the Sun has assumed increasing importance. However, such long-range, decadal-scale space weather prediction has remained a great challenge as evident in the diverging forecasts for solar cycle 24. Based on recently acquired understanding of the physics of solar cycle predictability, we have devised a scheme to extend the forecasting window of solar cycles. Utilizing this we present an early forecast for sunspot cycle 25 which would be of use for space mission planning, satellite life-time estimates, and assessment of the long-term impacts of space weather on technological assets and planetary atmospheres.

Assessment of fatigue life of remanufactured impeller based on FEA

NASA Astrophysics Data System (ADS)

Xu, Lei; Cao, Huajun; Liu, Hailong; Zhang, Yubo

2016-09-01

Predicting the fatigue life of remanufactured centrifugal compressor impellers is a critical problem. In this paper, the S-N curve data were obtained by combining experimentation and theory deduction. The load spectrum was compiled by the rain-flow counting method based on the comprehensive consideration of the centrifugal force, residual stress, and aerodynamic loads in the repair region. A fatigue life simulation model was built, and fatigue life was analyzed based on the fatigue cumulative damage rule. Although incapable of providing a high-precision prediction, the simulation results were useful for the analysis of fatigue life impact factors and fatigue fracture areas. Results showed that the load amplitude greatly affected fatigue life, the impeller was protected from running at over-speed, and the predicted fatigue life was satisfied within the next service cycle safely at the rated speed.

How Family Status and Social Security Claiming Options Shape Optimal Life Cycle Portfolios

PubMed Central

Hubener, Andreas; Maurer, Raimond; Mitchell, Olivia S.

2017-01-01

We show how optimal household decisions regarding work, retirement, saving, portfolio allocations, and life insurance are shaped by the complex financial options embedded in U.S. Social Security rules and uncertain family transitions. Our life cycle model predicts sharp consumption drops on retirement, an age-62 peak in claiming rates, and earlier claiming by wives versus husbands and single women. Moreover, life insurance is mainly purchased on men’s lives. Our model, which takes Social Security rules seriously, generates wealth and retirement outcomes that are more consistent with the data, in contrast to earlier and less realistic models. PMID:28659659

Predict the fatigue life of crack based on extended finite element method and SVR

NASA Astrophysics Data System (ADS)

Song, Weizhen; Jiang, Zhansi; Jiang, Hui

2018-05-01

Using extended finite element method (XFEM) and support vector regression (SVR) to predict the fatigue life of plate crack. Firstly, the XFEM is employed to calculate the stress intensity factors (SIFs) with given crack sizes. Then predicetion model can be built based on the function relationship of the SIFs with the fatigue life or crack length. Finally, according to the prediction model predict the SIFs at different crack sizes or different cycles. Because of the accuracy of the forward Euler method only ensured by the small step size, a new prediction method is presented to resolve the issue. The numerical examples were studied to demonstrate the proposed method allow a larger step size and have a high accuracy.

Induction of Phase Variation Events in the Life Cycle of the Marine Coccolithophorid Emiliania huxleyi

PubMed Central

Laguna, Richard; Romo, Jesus; Read, Betsy A.; Wahlund, Thomas M.

2001-01-01

Emiliania huxleyi is a unicellular marine alga that is considered to be the world's major producer of calcite. The life cycle of this alga is complex and is distinguished by its ability to synthesize exquisitely sculptured calcium carbonate cell coverings known as coccoliths. These structures have been targeted by materials scientists for applications relating to the chemistry of biomedical materials, robust membranes for high-temperature separation technology, lightweight ceramics, and semiconductor design. To date, however, the molecular and biochemical events controlling coccolith production have not been determined. In addition, little is known about the life cycle of E. huxleyi and the environmental and physiological signals triggering phase switching between the diploid and haploid life cycle stages. We have developed laboratory methods for inducing phase variation between the haploid (S-cell) and diploid (C-cell) life cycle stages of E. huxleyi. Plating E. huxleyi C cells on solid media was shown to induce phase switching from the C-cell to the S-cell life cycle stage, the latter of which has been maintained for over 2 years under these conditions. Pure cultures of S cells were obtained for the first time. Laboratory conditions for inducing phase switching from the haploid stage to the diploid stage were also established. Regeneration of the C-cell stage from pure cultures of S cells followed a predictable pattern involving formation of large aggregations of S cells and the subsequent production of cultures consisting predominantly of diploid C cells. These results demonstrate the ability to manipulate the life cycle of E. huxleyi under controlled laboratory conditions, providing us with powerful tools for the development of genetic techniques for analysis of coccolithogenesis and for investigating the complex life cycle of this important marine alga. PMID:11525973

MDOT Pavement Management System : Prediction Models and Feedback System

DOT National Transportation Integrated Search

2000-10-01

As a primary component of a Pavement Management System (PMS), prediction models are crucial for one or more of the following analyses: : maintenance planning, budgeting, life-cycle analysis, multi-year optimization of maintenance works program, and a...

SSME main combustion chamber life prediction

NASA Technical Reports Server (NTRS)

Cook, R. T.; Fryk, E. E.; Newell, J. F.

1983-01-01

Typically, low cycle fatigue life is a function of the cyclic strain range, the material properties, and the operating temperature. The reusable life is normally defined by the number of strain cycles that can be accrued before severe material degradation occurs. Reusable life is normally signified by the initiation or propagation of surface cracks. Hot-fire testing of channel wall combustors has shown significant mid-channel wall thinning or deformation during accrued cyclic testing. This phenomenon is termed cyclic-creep and appears to be significantly accelerated at elevated surface temperatures. This failure mode was analytically modelled. The cyclic life of the baseline SSME-MCC based on measured calorimeter heat transfer data, and the life sensitivity of local hot spots caused by injector effects were determined. Four life enhanced designs were assessed.

Actions of glucocorticoids at a seasonal baseline as compared to stress-related levels in the regulation of periodic life processes.

PubMed

Landys, Meta M; Ramenofsky, Marilyn; Wingfield, John C

2006-09-01

For decades, demands associated with the predictable life-history cycle have been considered stressful and have not been distinguished from stress that occurs in association with unpredictable and life-threatening perturbations in the environment. The recent emergence of the concept of allostasis distinguishes behavioral and physiological responses to predictable routines as opposed to unpredictable perturbations, and allows for their comparison within one theoretical framework. Glucocorticosteroids (GCs) have been proposed as important mediators of allostasis, as they allow for rapid readjustment and support of behavior and physiology in response to predictable and unpredictable demands (allostatic load). Much work has already been done in defining GC action at the high concentrations that accompany life-threatening perturbations. However, less is known about the role of GCs in relation to daily and seasonal life processes. In this review, we summarize the known behavioral and physiological effects of GCs relating to the predictable life-history cycle, paying particular attention to feeding behavior, locomotor activity and energy metabolism. Although we utilize a comparative approach, emphasis is placed on birds. In addition, we briefly review effects of GCs at stress-related concentrations to test the hypothesis that different levels of GCs play specific and distinct roles in the regulation of life processes and, thus, participate in the promotion of different physiological states. We also examine the receptor types through which GC action may be mediated and suggest mechanisms whereby different GC concentrations may exert their actions. In conclusion, we argue that biological actions of GCs at "non-stress" seasonal concentrations play a critical role in the adjustment of responses that accompany predictable variability in the environment and demand more careful consideration in future studies.

Qualification of Life Extension Schemes for Engine Components (Homologation des Programmes de Prolongation du cycle de vie des Organes Moteur)

DTIC Science & Technology

1999-03-01

cycle managers include (1) improving the durability of components through material substitution, or the addition of protective coatings, (2) returning... including in service trials, is required to demonstrate that the repaired and/or modified component is safe to use and remains so once returned to...Better Turbine Materials and Technology Including 5 Predicted Life Improvements by T.J. Williams Repair Developments to Fit Customer Needs (Presented

Fatigue properties of JIS H3300 C1220 copper for strain life prediction

NASA Astrophysics Data System (ADS)

Harun, Muhammad Faiz; Mohammad, Roslina

2018-05-01

The existing methods for estimating strain life parameters are dependent on the material's monotonic tensile properties. However, a few of these methods yield quite complicated expressions for calculating fatigue parameters, and are specific to certain groups of materials only. The Universal Slopes method, Modified Universal Slopes method, Uniform Material Law, the Hardness method, and Medians method are a few existing methods for predicting strain-life fatigue based on monotonic tensile material properties and hardness of material. In the present study, nine methods for estimating fatigue life and properties are applied on JIS H3300 C1220 copper to determine the best methods for strain life estimation of this ductile material. Experimental strain-life curves are compared to estimations obtained using each method. Muralidharan-Manson's Modified Universal Slopes method and Bäumel-Seeger's method for unalloyed and low-alloy steels are found to yield batter accuracy in estimating fatigue life with a deviation of less than 25%. However, the prediction of both methods only yield much better accuracy for a cycle of less than 1000 or for strain amplitudes of more than 1% and less than 6%. Manson's Original Universal Slopes method and Ong's Modified Four-Point Correlation method are found to predict the strain-life fatigue of copper with better accuracy for a high number of cycles of strain amplitudes of less than 1%. The differences between mechanical behavior during monotonic and cyclic loading and the complexity in deciding the coefficient in an equation are probably the reason for the lack of a reliable method for estimating fatigue behavior using the monotonic properties of a group of materials. It is therefore suggested that a differential approach and new expressions be developed to estimate the strain-life fatigue parameters for ductile materials such as copper.

A transient plasticity study and low cycle fatigue analysis of the Space Station Freedom photovoltaic solar array blanket

NASA Technical Reports Server (NTRS)

Armand, Sasan C.; Liao, Mei-Hwa; Morris, Ronald W.

1990-01-01

The Space Station Freedom photovoltaic solar array blanket assembly is comprised of several layers of materials having dissimilar elastic, thermal, and mechanical properties. The operating temperature of the solar array, which ranges from -75 to +60 C, along with the material incompatibility of the blanket assembly components combine to cause an elastic-plastic stress in the weld points of the assembly. The weld points are secondary structures in nature, merely serving as electrical junctions for gathering the current. The thermal mechanical loading of the blanket assembly operating in low earth orbit continually changes throughout each 90 min orbit, which raises the possibility of fatigue induced failure. A series of structural analyses were performed in an attempt to predict the fatigue life of the solar cell in the Space Station Freedom photovoltaic array blanket. A nonlinear elastic-plastic MSC/NASTRAN analysis followed by a fatigue calculation indicated a fatigue life of 92,000 to 160,000 cycles for the solar cell weld tabs. Additional analyses predict a permanent buckling phenomenon in the copper interconnect after the first loading cycle. This should reduce or eliminate the pulling of the copper interconnect on the joint where it is welded to the silicon solar cell. It is concluded that the actual fatigue life of the solar array blanket assembly should be significantly higher than the calculated 92,000 cycles, and thus the program requirement of 87,500 cycles (orbits) will be met. Another important conclusion that can be drawn from the overall analysis is that, the strain results obtained from the MSC/NASTRAN nonlinear module are accurate to use for low-cycle fatigue analysis, since both thermal cycle testing of solar cells and analysis have shown higher fatigue life than the minimum program requirement of 87,500 cycles.

Data-Driven Mechanistic Modeling of Influence of Microstructure on High-Cycle Fatigue Life of Nickel Titanium

NASA Astrophysics Data System (ADS)

Kafka, Orion L.; Yu, Cheng; Shakoor, Modesar; Liu, Zeliang; Wagner, Gregory J.; Liu, Wing Kam

2018-04-01

A data-driven mechanistic modeling technique is applied to a system representative of a broken-up inclusion ("stringer") within drawn nickel-titanium wire or tube, e.g., as used for arterial stents. The approach uses a decomposition of the problem into a training stage and a prediction stage. It is applied to compute the fatigue crack incubation life of a microstructure of interest under high-cycle fatigue. A parametric study of a matrix-inclusion-void microstructure is conducted. The results indicate that, within the range studied, a larger void between halves of the inclusion increases fatigue life, while larger inclusion diameter reduces fatigue life.

A mathematical model for predicting the life of polymer electrolyte fuel cell membranes subjected to hydration cycling

NASA Astrophysics Data System (ADS)

Burlatsky, S. F.; Gummalla, M.; O'Neill, J.; Atrazhev, V. V.; Varyukhin, A. N.; Dmitriev, D. V.; Erikhman, N. S.

2012-10-01

Under typical Polymer Electrolyte Membrane Fuel Cell (PEMFC) fuel cell operating conditions, part of the membrane electrode assembly is subjected to humidity cycling due to variation of inlet gas RH and/or flow rate. Cyclic membrane hydration/dehydration would cause cyclic swelling/shrinking of the unconstrained membrane. In a constrained membrane, it causes cyclic stress resulting in mechanical failure in the area adjacent to the gas inlet. A mathematical modeling framework for prediction of the lifetime of a PEMFC membrane subjected to hydration cycling is developed in this paper. The model predicts membrane lifetime as a function of RH cycling amplitude and membrane mechanical properties. The modeling framework consists of three model components: a fuel cell RH distribution model, a hydration/dehydration induced stress model that predicts stress distribution in the membrane, and a damage accrual model that predicts membrane lifetime. Short descriptions of the model components along with overall framework are presented in the paper. The model was used for lifetime prediction of a GORE-SELECT membrane.

Some practical observations on the accelerated testing of Nickel-Cadmium Cells

NASA Technical Reports Server (NTRS)

Mcdermott, P. P.

1979-01-01

A large scale test of 6.0 Ah Nickel-Cadmium Cells conducted at the Naval Weapons Support Center, Crane, Indiana has demonstrated a methodology for predicting battery life based on failure data from cells cycled in an accelerated mode. After examining eight variables used to accelerate failure, it was determined that temperature and depth of discharge were the most reliable and efficient parameters for use in accelerating failure and for predicting life.

Thermal-mechanical fatigue of high temperature structural materials

NASA Astrophysics Data System (ADS)

Renauld, Mark Leo

Experimental and analytical methods were developed to address the effect of thermal-mechanical strain cycling on high temperature structural materials under uniaxial and biaxial stress states. Two materials were used in the investigation, a nickel-base superalloy of low ductility, IN-738LC and a high ductility material, 316 stainless steel. A uniaxial life prediction model for the IN-738LC material was based on tensile hysteresis energy measured in stabilized, mid-life hysteresis loops. Hold-time effects and temperature cycling were incorporated in the hysteresis energy approach. Crack growth analysis was also included in the model to predict the number of TMF cycles to initiate and grow a fatigue crack through the coating. The nickel-base superalloy, IN-738LC, was primarily tested in out-of-phase (OP) TMF with a temperature range from 482-871sp°C (900-1600sp°F) under continuous and compressive hold-time cycling. IN-738LC fatigue specimens were coated either with an aluminide, NiCoCrAlHfSi overlay or CoNiCrAlY overlay coating on the outer surface of the specimen. Metallurgical failure analysis via optical and scanning electron microscopy, was used to characterize failure behavior of both substrate and coating materials. Type 316 SS was subjected to continuous biaxial strain cycling with an in-phase (IP) TMF loading and a temperature range from 399-621sp°C (750-1150sp°F). As a result, a biaxial TMF life prediction model was proposed on the basis of an extended isothermal fatigue model. The model incorporates a frequency effect and phase factors to assess the different damage mechanisms observed during TMF loading. The model was also applied to biaxial TMF data generated on uncoated IN-738LC.

Deciphering RNA Regulatory Elements Involved in the Developmental and Environmental Gene Regulation of Trypanosoma brucei.

PubMed

Gazestani, Vahid H; Salavati, Reza

2015-01-01

Trypanosoma brucei is a vector-borne parasite with intricate life cycle that can cause serious diseases in humans and animals. This pathogen relies on fine regulation of gene expression to respond and adapt to variable environments, with implications in transmission and infectivity. However, the involved regulatory elements and their mechanisms of actions are largely unknown. Here, benefiting from a new graph-based approach for finding functional regulatory elements in RNA (GRAFFER), we have predicted 88 new RNA regulatory elements that are potentially involved in the gene regulatory network of T. brucei. We show that many of these newly predicted elements are responsive to both transcriptomic and proteomic changes during the life cycle of the parasite. Moreover, we found that 11 of predicted elements strikingly resemble previously identified regulatory elements for the parasite. Additionally, comparison with previously predicted motifs on T. brucei suggested the superior performance of our approach based on the current limited knowledge of regulatory elements in T. brucei.

Fatigue crack growth and life prediction under mixed-mode loading

NASA Astrophysics Data System (ADS)

Sajith, S.; Murthy, K. S. R. K.; Robi, P. S.

2018-04-01

Fatigue crack growth life as a function of crack length is essential for the prevention of catastrophic failures from damage tolerance perspective. In damage tolerance design approach, principles of fracture mechanics are usually applied to predict the fatigue life of structural components. Numerical prediction of crack growth versus number of cycles is essential in damage tolerance design. For cracks under mixed mode I/II loading, modified Paris law (d/a d N =C (ΔKe q ) m ) along with different equivalent stress intensity factor (ΔKeq) model is used for fatigue crack growth rate prediction. There are a large number of ΔKeq models available for the mixed mode I/II loading, the selection of proper ΔKeq model has significant impact on fatigue life prediction. In the present investigation, the performance of ΔKeq models in fatigue life prediction is compared with respect to the experimental findings as there are no guidelines/suggestions available on the selection of these models for accurate and/or conservative predictions of fatigue life. Within the limitations of availability of experimental data and currently available numerical simulation techniques, the results of present study attempt to outline models that would provide accurate and conservative life predictions. Such a study aid the numerical analysts or engineers in the proper selection of the model for numerical simulation of the fatigue life. Moreover, the present investigation also suggests a procedure to enhance the accuracy of life prediction using Paris law.

Advanced High Cycle Fatigue (HCF) Life Assurance Methodologies

DTIC Science & Technology

2004-07-01

Fatigue in 2024 - T351 Aluminum Alloy , Wear, 221(1), pp 24-36 (1998) 27. Doner, M., Bain, K.R., and Adams, J.H... alloy , PWA 1484, where temperature and orientation effects both have to be taken into account. Both fracture mechanics and fatigue life methods... effect on predicted fatigue life . On average, the fatigue life is several orders of magnitude less when residual stresses are included. The

A creep cavity growth model for creep-fatigue life prediction of a unidirectional W/Cu composite

NASA Astrophysics Data System (ADS)

Kim, Young-Suk; Verrilli, Michael J.; Halford, Gary R.

1992-05-01

A microstructural model was developed to predict creep-fatigue life in a (0)(sub 4), 9 volume percent tungsten fiber-reinforced copper matrix composite at the temperature of 833 K. The mechanism of failure of the composite is assumed to be governed by the growth of quasi-equilibrium cavities in the copper matrix of the composite, based on the microscopically observed failure mechanisms. The methodology uses a cavity growth model developed for prediction of creep fracture. Instantaneous values of strain rate and stress in the copper matrix during fatigue cycles were calculated and incorporated in the model to predict cyclic life. The stress in the copper matrix was determined by use of a simple two-bar model for the fiber and matrix during cyclic loading. The model successfully predicted the composite creep-fatigue life under tension-tension cyclic loading through the use of this instantaneous matrix stress level. Inclusion of additional mechanisms such as cavity nucleation, grain boundary sliding, and the effect of fibers on matrix-stress level would result in more generalized predictions of creep-fatigue life.

A creep cavity growth model for creep-fatigue life prediction of a unidirectional W/Cu composite

NASA Technical Reports Server (NTRS)

Kim, Young-Suk; Verrilli, Michael J.; Halford, Gary R.

1992-01-01

A microstructural model was developed to predict creep-fatigue life in a (0)(sub 4), 9 volume percent tungsten fiber-reinforced copper matrix composite at the temperature of 833 K. The mechanism of failure of the composite is assumed to be governed by the growth of quasi-equilibrium cavities in the copper matrix of the composite, based on the microscopically observed failure mechanisms. The methodology uses a cavity growth model developed for prediction of creep fracture. Instantaneous values of strain rate and stress in the copper matrix during fatigue cycles were calculated and incorporated in the model to predict cyclic life. The stress in the copper matrix was determined by use of a simple two-bar model for the fiber and matrix during cyclic loading. The model successfully predicted the composite creep-fatigue life under tension-tension cyclic loading through the use of this instantaneous matrix stress level. Inclusion of additional mechanisms such as cavity nucleation, grain boundary sliding, and the effect of fibers on matrix-stress level would result in more generalized predictions of creep-fatigue life.

Interference-Fit-Fastener Investigation

DTIC Science & Technology

1975-09-01

Crack Initiation . .*. . . .* e . . .*. . . .*. 20 Figure 9. Actual and Predicted Fatigue Life Behavior of Notched Open Hole Plates for 2024 - T351 ... Aluminum (Reference 19) * .. . . . . . . . .. . 22 Figure 10. Gage I Strain Response With Cycles . . . . . . . . 24 Figure 11. Fatigue Damage - Life ... Fatigue Behavior", Effect of Environment and Complex Load History on Fatigue Life , ASTM STP 462, pp 74-91 (1970). (7) Grosskreutz, J. C., and Shaw, G. G

Life Prediction for a CMC Component Using the NASALIFE Computer Code

NASA Technical Reports Server (NTRS)

Gyekenyesi, John Z.; Murthy, Pappu L. N.; Mital, Subodh K.

2005-01-01

The computer code, NASALIFE, was used to provide estimates for life of an SiC/SiC stator vane under varying thermomechanical loading conditions. The primary intention of this effort is to show how the computer code NASALIFE can be used to provide reasonable estimates of life for practical propulsion system components made of advanced ceramic matrix composites (CMC). Simple loading conditions provided readily observable and acceptable life predictions. Varying the loading conditions such that low cycle fatigue and creep were affected independently provided expected trends in the results for life due to varying loads and life due to creep. Analysis was based on idealized empirical data for the 9/99 Melt Infiltrated SiC fiber reinforced SiC.

Mariner Jupiter/Saturn LCSSE thruster/valve assembly and injection propulsion unit rocket engine assemblies: 0.2-lbf T/VA development and margin limit test report

NASA Technical Reports Server (NTRS)

Clark, E. C.

1975-01-01

Thruster valve assemblies (T/VA's) were subjected to the development test program for the combined JPL Low-Cost Standardized Spacecraft Equipment (LCSSE) and Mariner Jupiter/Saturn '77 spacecraft (MJS) programs. The development test program was designed to achieve the following program goals: (1) demonstrate T/VA design compliance with JPL Specifications, (2) to conduct a complete performance Cf map of the T/VA over the full operating range of environment, (3) demonstrate T/VA life capability and characteristics of life margin for steady-state limit cycle and momentum wheel desaturation duty cycles, (4) verification of structural design capability, and (5) generate a computerized performance model capable of predicting T/VA operation over pressures ranging from 420 to 70 psia, propellant temperatures ranging from 140 F to 40 F, pulse widths of 0.008 to steady-state operation with unlimited duty cycle capability, and finally predict the transient performance associated with reactor heatup during any given duty cycle, start temperature, feed pressure, and propellant temperature conditions.

Life prediction modeling based on cyclic damage accumulation

NASA Technical Reports Server (NTRS)

Nelson, Richard S.

1988-01-01

A high temperature, low cycle fatigue life prediction method was developed. This method, Cyclic Damage Accumulation (CDA), was developed for use in predicting the crack initiation lifetime of gas turbine engine materials, where initiation was defined as a 0.030 inch surface length crack. A principal engineering feature of the CDA method is the minimum data base required for implementation. Model constants can be evaluated through a few simple specimen tests such as monotonic loading and rapic cycle fatigue. The method was expanded to account for the effects on creep-fatigue life of complex loadings such as thermomechanical fatigue, hold periods, waveshapes, mean stresses, multiaxiality, cumulative damage, coatings, and environmental attack. A significant data base was generated on the behavior of the cast nickel-base superalloy B1900+Hf, including hundreds of specimen tests under such loading conditions. This information is being used to refine and extend the CDA life prediction model, which is now nearing completion. The model is also being verified using additional specimen tests on wrought INCO 718, and the final version of the model is expected to be adaptable to most any high-temperature alloy. The model is currently available in the form of equations and related constants. A proposed contract addition will make the model available in the near future in the form of a computer code to potential users.

Assessment of Solder Joint Fatigue Life Under Realistic Service Conditions

NASA Astrophysics Data System (ADS)

Hamasha, Sa'd.; Jaradat, Younis; Qasaimeh, Awni; Obaidat, Mazin; Borgesen, Peter

2014-12-01

The behavior of lead-free solder alloys under complex loading scenarios is still not well understood. Common damage accumulation rules fail to account for strong effects of variations in cycling amplitude, and random vibration test results cannot be interpreted in terms of performance under realistic service conditions. This is a result of the effects of cycling parameters on materials properties. These effects are not yet fully understood or quantitatively predictable, preventing modeling based on parameters such as strain, work, or entropy. Depending on the actual spectrum of amplitudes, Miner's rule of linear damage accumulation has been shown to overestimate life by more than an order of magnitude, and greater errors are predicted for other combinations. Consequences may be particularly critical for so-called environmental stress screening. Damage accumulation has, however, been shown to scale with the inelastic work done, even if amplitudes vary. This and the observation of effects of loading history on subsequent work per cycle provide for a modified damage accumulation rule which allows for the prediction of life. Individual joints of four different Sn-Ag-Cu-based solder alloys (SAC305, SAC105, SAC-Ni, and SACXplus) were cycled in shear at room temperature, alternating between two different amplitudes while monitoring the evolution of the effective stiffness and work per cycle. This helped elucidate general trends and behaviors that are expected to occur in vibrations of microelectronics assemblies. Deviations from Miner's rule varied systematically with the combination of amplitudes, the sequences of cycles, and the strain rates in each. The severity of deviations also varied systematically with Ag content in the solder, but major effects were observed for all the alloys. A systematic analysis was conducted to assess whether scenarios might exist in which the more fatigue-resistant high-Ag alloys would fail sooner than the lower-Ag ones.

From concept(ion) to life after death/the grave: The 'natural' history and life cycle(s) of novel psychoactive substances (NPS).

PubMed

Corkery, John Martin; Orsolini, Laura; Papanti, Duccio; Schifano, Fabrizio

2017-05-01

A range of information needs should be met in order to better understand and predict the longevity/existence of novel psychoactive substances (NPS). This conceptual paper argues that one way of assessing how long a molecule may be around is to document how the life cycles or natural histories of 'traditional' drugs and NPS evolve. The earliest indication of the possible appearance of a new substance might be evidenced on the DeepWeb. However, this means they are less visible, in line with the clandestine nature of drug use and supply. Therefore, monitoring discussion groups/fora needs the development of new methods compared to those used in the Surface Net. Issues needing consideration in establishing NPS life cycles are outlined here, together with the probable outcomes that could result. The approach advocated means that it should be easier to identify which NPS are likely to come up or are emerging in real time, and, therefore, pre-empt/prevent their supply. Copyright © 2017 John Wiley & Sons, Ltd.

An analysis of isothermal, bithermal, and thermomechanical fatigue data of Haynes 188 and B1900+Hf by energy considerations

NASA Technical Reports Server (NTRS)

Radhakrishnan, V. M.; Kalluri, Sreeramesh; Halford, Gary R.

1993-01-01

The low-cycle fatigue behavior of Haynes 188 and B1900+Hf under isothermal, bithermal, and thermomechanical loading conditions has been analyzed on the basis of the total hysteresis energy expended per cycle. It has been observed that in the case of isothermal fatigue the total hysteresis energy correlates well with the fatigue life. In the case of bithermal 'high rate' fatigue, for a given total hysteresis energy per cycle, the fatigue life is equal to or greater than the isothermal fatigue life at the maximum bithermal temperature. This observation could be used to establish a lower bound on life for design purposes. In one case of bithermal creep-fatigue and in thermomechanical fatigue, the life is shorter than that corresponding to the isothermal life at the maximum temperature. The energy supplied, per se, may not always give a systematic correlation with the fatigue life in the cases where time-dependent creep and environmental effects are encountered. Thus, in bithermal creep-fatigue and thermomechanical fatigue, the role of creep and environment and their dependence on the energy supplied have to be properly accounted for before the energy term can be used for life prediction.

Low-carbon, low-water scenarios with life cycle water factors for ES&T paper

EPA Pesticide Factsheets

The dataset includes all data used in the creation of figures and graphs in the paper: Scenarios for low carbon and low water electric power plant operations: implications for upstream water use. Data includes regional electricity mixes, full life cycle water use, and water use for each life cycle stage. These encompass a range of scenarios out to 2050, and should not be used as predictions, forecasts or official baselines. The scenarios and results are for research purposes only, and do not represent current or future U.S. EPA policies or regulations.This dataset is associated with the following publication:Dodder , R., J. Barnwell , and W. Yelverton. Scenarios for low carbon and low water electric power plant operations: implications for upstream water use. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 50(21): 11460-11470, (2016).

Reliability and Creep/Fatigue Analysis of a CMC Component

NASA Technical Reports Server (NTRS)

Murthy, Pappu L. N.; Mital, Subodh K.; Gyekenyesi, John Z.; Gyekenyesi, John P.

2007-01-01

High temperature ceramic matrix composites (CMC) are being explored as viable candidate materials for hot section gas turbine components. These advanced composites can potentially lead to reduced weight and enable higher operating temperatures requiring less cooling; thus leading to increased engine efficiencies. There is a need for convenient design tools that can accommodate various loading conditions and material data with their associated uncertainties to estimate the minimum predicted life as well as the failure probabilities of a structural component. This paper presents a review of the life prediction and probabilistic analyses performed for a CMC turbine stator vane. A computer code, NASALife, is used to predict the life of a 2-D woven silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) turbine stator vane due to a mission cycle which induces low cycle fatigue and creep. The output from this program includes damage from creep loading, damage due to cyclic loading and the combined damage due to the given loading cycle. Results indicate that the trends predicted by NASALife are as expected for the loading conditions used for this study. In addition, a combination of woven composite micromechanics, finite element structural analysis and Fast Probability Integration (FPI) techniques has been used to evaluate the maximum stress and its probabilistic distribution in a CMC turbine stator vane. Input variables causing scatter are identified and ranked based upon their sensitivity magnitude. Results indicate that reducing the scatter in proportional limit strength of the vane material has the greatest effect in improving the overall reliability of the CMC vane.

Marital Satisfaction in Later Life: The Effects of Nonmarital Roles.

ERIC Educational Resources Information Center

Lee, Gary R.

1988-01-01

Predicted that marital satisfaction would be higher in later stages of life cycle because of diminishing demands of nonmarital roles. Data from 2,327 older married persons showed that departure of children was associated with higher levels of marital satisfaction; other hypotheses based on role overload theory received no support and were…

Effect of Prior Aging on Fatigue Behavior of IM7/BMI 5250-4 Composite at 191 C

DTIC Science & Technology

2007-06-01

6 Figure 4. Three stages of fatigue life cycle for general material ....................................... 9 Figure 5...calibration ........ 24 vii Figure 17. Omega thermocouple reader setup .................................................................. 26 Figure...cost and fleet readiness. To assure long- term durability and structural integrity of HTPMC components, reliable experimentally- based life -prediction

A Novel Approach to Rotorcraft Damage Tolerance

NASA Technical Reports Server (NTRS)

Forth, Scott C.; Everett, Richard A.; Newman, John A.

2002-01-01

Damage-tolerance methodology is positioned to replace safe-life methodologies for designing rotorcraft structures. The argument for implementing a damage-tolerance method comes from the fundamental fact that rotorcraft structures typically fail by fatigue cracking. Therefore, if technology permits prediction of fatigue-crack growth in structures, a damage-tolerance method should deliver the most accurate prediction of component life. Implementing damage-tolerance (DT) into high-cycle-fatigue (HCF) components will require a shift from traditional DT methods that rely on detecting an initial flaw with nondestructive inspection (NDI) methods. The rapid accumulation of cycles in a HCF component will result in a design based on a traditional DT method that is either impractical because of frequent inspections, or because the design will be too heavy to operate efficiently. Furthermore, once a HCF component develops a detectable propagating crack, the remaining fatigue life is short, sometimes less than one flight hour, which does not leave sufficient time for inspection. Therefore, designing a HCF component will require basing the life analysis on an initial flaw that is undetectable with current NDI technology.

Estimation of Axial Fretting Fatigue Life at Elevated Temperatures Using Critical Distance Theory

NASA Astrophysics Data System (ADS)

Majzoobi, G. H.; Azhdarzadeh, P.

Fretting fatigue life is traditionally estimated by experiment. The objective of this work is to introduce a special approach for estimation of axial fretting fatigue life at elevated temperatures from plain fatigue test based on the critical distance theory. The method uses Fatemi-Socie parameter as a multiaxial criterion to compute the stress multiaxiality on focus path. This method considers only elastic behavior for materials, and two characteristic diagrams are obtained from plain fatigue tests on two U-shaped and V-shaped notched specimens. The results showed reasonable agreement between the predictions by the proposed method and the experiments for ambient temperature. For elevated temperatures, the results indicated that the predicted fretting fatigue life was considerably overestimated in the low cycle fatigue (LCF) regime and underestimated in the high cycle fatigue (HCF) region with respect to experimental measurements. The reason for such discrepancy is believed to be due to the complex behavior of AL 7075-T6, which exhibits at elevated temperatures because of the problems such as aging, oxidation and reduction of strength.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Kandler; Shi, Ying; Santhanagopalan, Shriram

Predictive models of Li-ion battery lifetime must consider a multiplicity of electrochemical, thermal, and mechanical degradation modes experienced by batteries in application environments. To complicate matters, Li-ion batteries can experience different degradation trajectories that depend on storage and cycling history of the application environment. Rates of degradation are controlled by factors such as temperature history, electrochemical operating window, and charge/discharge rate. We present a generalized battery life prognostic model framework for battery systems design and control. The model framework consists of trial functions that are statistically regressed to Li-ion cell life datasets wherein the cells have been aged under differentmore » levels of stress. Degradation mechanisms and rate laws dependent on temperature, storage, and cycling condition are regressed to the data, with multiple model hypotheses evaluated and the best model down-selected based on statistics. The resulting life prognostic model, implemented in state variable form, is extensible to arbitrary real-world scenarios. The model is applicable in real-time control algorithms to maximize battery life and performance. We discuss efforts to reduce lifetime prediction error and accommodate its inevitable impact in controller design.« less

Reliability of Tin Silver Copper and mixed solders under variable loading conditions

NASA Astrophysics Data System (ADS)

Jaradat, Younis

Industry use of lead free solder joints necessitates accurate modeling in predicting life in service. Yet, current extrapolations of accelerated test results do not actuate realistic conditions. This research focuses on joint properties of Pb-mixed and Pb-free solder alloys in order to explain material behavior subject to certain test conditions, i.e., varying cycling amplitudes. Additionally, this research will begin with extensive studies on backward compatible solder joints from the material's behavior to its reliability under displacement and load controlled fatigue tests. We address the evolution of the joint's microstructure ergo its properties and performance (mixed solder joints). The present work reports results of reflowing 30 mil SAC305 balls onto Cu, and ENIG coated BGA pads with different amounts of SnPb paste, aging and/or cycling the joints and inspecting the microstructure by cross polarizer microscopy and SEM. We found that the addition of small amounts of Pb had significant effects on solidification during cool-down from reflow, and consequently the initial microstructure. In terms of the varying cycling amplitude study, we note how realistic service conditions are almost never well approximated by cycling with fixed amplitudes. Recent results have demonstrated the consistent breakdown of common damage accumulation rules. In isothermal cycling tests the remaining life, after a step-down in amplitude, was invariably shorter than predicted by such a rule, while a step-up tended to have the opposite effect. The present work offers a mechanistic explanation for this and the basis for a practical approach to the assessment of life under service conditions. Realistic BGA joints were cycled individually in a micromechanical tester, monitoring the solder stiffness and the inelastic energy deposition. Cycling was seen to first cause rapid hardening, followed by leveling off in a 'cyclic saturation' stage and eventually the initiation and growth of a crack until failure. A temporary increase in amplitude during cycling caused a lasting reduction in hardness, and thus enhanced inelastic energy deposition and damage evolution, after the fact. This factor dominates during repeated increases and decreases, eventually shortening the remaining life dramatically

A Model of BGA Thermal Fatigue Life Prediction Considering Load Sequence Effects

PubMed Central

Hu, Weiwei; Li, Yaqiu; Sun, Yufeng; Mosleh, Ali

2016-01-01

Accurate testing history data is necessary for all fatigue life prediction approaches, but such data is always deficient especially for the microelectronic devices. Additionally, the sequence of the individual load cycle plays an important role in physical fatigue damage. However, most of the existing models based on the linear damage accumulation rule ignore the sequence effects. This paper proposes a thermal fatigue life prediction model for ball grid array (BGA) packages to take into consideration the load sequence effects. For the purpose of improving the availability and accessibility of testing data, a new failure criterion is discussed and verified by simulation and experimentation. The consequences for the fatigue underlying sequence load conditions are shown. PMID:28773980

Comparison of Battery Life Across Real-World Automotive Drive-Cycles (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, K.; Earleywine, M.; Wood, E.

2011-11-01

Laboratories run around-the-clock aging tests to try to understand as quickly as possible how long new Li-ion battery designs will last under certain duty cycles. These tests may include factors such as duty cycles, climate, battery power profiles, and battery stress statistics. Such tests are generally accelerated and do not consider possible dwell time at high temperatures and states-of-charge. Battery life-predictive models provide guidance as to how long Li-ion batteries may last under real-world electric-drive vehicle applications. Worst-case aging scenarios are extracted from hundreds of real-world duty cycles developed from vehicle travel surveys. Vehicles examined included PHEV10 and PHEV40 EDVsmore » under fixed (28 degrees C), limited cooling (forced ambient temperature), and aggressive cooling (20 degrees C chilled liquid) scenarios using either nightly charging or opportunity charging. The results show that battery life expectancy is 7.8 - 13.2 years for the PHEV10 using a nightly charge in Phoenix, AZ (hot climate), and that the 'aggressive' cooling scenario can extend battery life by 1-3 years, while the 'limited' cooling scenario shortens battery life by 1-2 years. Frequent (opportunity) charging can reduce battery life by 1 year for the PHEV10, while frequent charging can extend battery life by one-half year.« less

Application of fracture mechanics and half-cycle method to the prediction of fatigue life of B-52 aircraft pylon components

NASA Technical Reports Server (NTRS)

Ko, W. L.; Carter, A. L.; Totton, W. W.; Ficke, J. M.

1989-01-01

Stress intensity levels at various parts of the NASA B-52 carrier aircraft pylon were examined for the case when the pylon store was the space shuttle solid rocket booster drop test vehicle. Eight critical stress points were selected for the pylon fatigue analysis. Using fracture mechanics and the half-cycle theory (directly or indirectly) for the calculations of fatigue-crack growth ,the remaining fatigue life (number of flights left) was estimated for each critical part. It was found that the two rear hooks had relatively short fatigue life and that the front hook had the shortest fatigue life of all the parts analyzed. The rest of the pylon parts were found to be noncritical because of their extremely long fatigue life associated with the low operational stress levels.

The fatigue life prediction of aluminium alloy using genetic algorithm and neural network

NASA Astrophysics Data System (ADS)

Susmikanti, Mike

2013-09-01

The behavior of the fatigue life of the industrial materials is very important. In many cases, the material with experiencing fatigue life cannot be avoided, however, there are many ways to control their behavior. Many investigations of the fatigue life phenomena of alloys have been done, but it is high cost and times consuming computation. This paper report the modeling and simulation approaches to predict the fatigue life behavior of Aluminum Alloys and resolves some problems of computation. First, the simulation using genetic algorithm was utilized to optimize the load to obtain the stress values. These results can be used to provide N-cycle fatigue life of the material. Furthermore, the experimental data was applied as input data in the neural network learning, while the samples data were applied for testing of the training data. Finally, the multilayer perceptron algorithm is applied to predict whether the given data sets in accordance with the fatigue life of the alloy. To achieve rapid convergence, the Levenberg-Marquardt algorithm was also employed. The simulations results shows that the fatigue behaviors of aluminum under pressure can be predicted. In addition, implementation of neural networks successfully identified a model for material fatigue life.

Utilize Cementitious High Carbon Fly Ash (CHCFA) to Stabilize Cold In-Place Recycled (CIR) Asphalt Pavement as Base Coarse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Haifang; Li, Xiaojun; Edil, Tuncer

The purpose of this study was to evaluate the performance of cementitious high carbon fly ash (CHCFA) stabilized recycled asphalt pavement as a base course material in a real world setting. Three test road cells were built at MnROAD facility in Minnesota. These cells have the same asphalt surface layers, subbases, and subgrades, but three different base courses: conventional crushed aggregates, untreated recycled pavement materials (RPM), and CHCFA stabilized RPM materials. During and after the construction of the three cells, laboratory and field tests were carried out to characterize the material properties. The test results were used in the mechanistic-empiricalmore » pavement design guide (MEPDG) to predict the pavement performance. Based on the performance prediction, the life cycle analyses of cost, energy consumption, and greenhouse gasses were performed. The leaching impacts of these three types of base materials were compared. The laboratory and field tests showed that fly ash stabilized RPM had higher modulus than crushed aggregate and RPM did. Based on the MEPDG performance prediction, the service life of the Cell 79 containing fly ash stabilized RPM, is 23.5 years, which is about twice the service life (11 years) of the Cell 77 with RPM base, and about three times the service life (7.5 years) of the Cell 78 with crushed aggregate base. The life cycle analysis indicated that the usage of the fly ash stabilized RPM as the base of the flexible pavement can significantly reduce the life cycle cost, the energy consumption, the greenhouse gases emission. Concentrations of many trace elements, particularly those with relatively low water quality standards, diminish over time as water flows through the pavement profile. For many elements, concentrations below US water drinking water quality standards are attained at the bottom of the pavement profile within 2-4 pore volumes of flow.« less

The PreViBOSS project: study the short term predictability of the visibility change during the Fog life cycle, from surface and satellite observation

NASA Astrophysics Data System (ADS)

Elias, T.; Haeffelin, M.; Ramon, D.; Gomes, L.; Brunet, F.; Vrac, M.; Yiou, P.; Hello, G.; Petithomme, H.

2010-07-01

Fog prejudices major activities as transport and Earth observation, by critically reducing atmospheric visibility with no continuity in time and space. Fog is also an essential factor of air quality and climate as it modifies particle properties of the surface atmospheric layer. Complexity, diversity and the fine scale of processes make uncertain by current numerical weather prediction models, not only visibility diagnosis but also fog event prediction. Extensive measurements of atmospheric parameters are made on the SIRTA since 1997 to document physical processes over the atmospheric column, in the Paris suburb area, typical of an environment intermittently under oceanic influence and affected by urban and industrial pollution. The ParisFog field campaign hosted in SIRTA during 6-month in winter 2006-2007 resulted in the deployment of instrumentation specifically dedicated to study physical processes in the fog life cycle: thermodynamical, radiative, dynamical, microphysical processes. Analysis of the measurements provided a preliminary climatology of the episodes of reduced visibility, chronology of processes was delivered by examining time series of measured parameters and a closure study was performed on optical and microphysical properties of particles (aerosols to droplets) during the life cycle of a radiative fog, providing the relative contribution of several particle groups to extinction in clear-sky conditions, in haze and in fog. PreViBOSS is a 3-year project scheduled to start this year. The aim is to improve the short term prediction of changes in atmospheric visibility, at a local scale. It proposes an innovative approach: applying the Generalised Additive Model statistical method to the detailed and extended dataset acquired at SIRTA. This method offers the opportunity to explore non linear relationships between parameters, which are not yet integrated in current numerical models. Emphasis will be put on aerosols and their impact on the fog life cycle. Furthermore, the data set of ground-based measurements will be completed by spaceborne observation of visible and infra red radiance performed by the METEOSAT mission.

A two-parameter model to predict fatigue life of high-strength steels in a very high cycle fatigue regime

NASA Astrophysics Data System (ADS)

Sun, Chengqi; Liu, Xiaolong; Hong, Youshi

2015-06-01

In this paper, ultrasonic (20 kHz) fatigue tests were performed on specimens of a high-strength steel in very high cycle fatigue (VHCF) regime. Experimental results showed that for most tested specimens failed in a VHCF regime, a fatigue crack originated from the interior of specimen with a fish-eye pattern, which contained a fine granular area (FGA) centered by an inclusion as the crack origin. Then, a two-parameter model is proposed to predict the fatigue life of high-strength steels with fish-eye mode failure in a VHCF regime, which takes into account the inclusion size and the FGA size. The model was verified by the data of present experiments and those in the literature. Furthermore, an analytic formula was obtained for estimating the equivalent crack growth rate within the FGA. The results also indicated that the stress intensity factor range at the front of the FGA varies within a small range, which is irrespective of stress amplitude and fatigue life.

Different Applications of FORTRACC: From Convective Clouds to thunderstorms and radar fields

NASA Astrophysics Data System (ADS)

Morales, C.; Machado, L. A.

2009-09-01

The algorithm Forecasting and Tracking the Evolution of Cloud Clusters (ForTraCC), Vila et al. (2008), has been employed operationally in Brazil since 2005 to track and forecast the development of convective clouds. This technique depicts the main morphological features of the cloud systems and most importantly it reconstructs its entire life cycle. Based on this information, several relationships that use the area expansion and convective and stratiform fraction are employed to predict the life time duration and cloud area. Because of these features, the civil defense and power companies are using this information to mitigate the damages in the population. Further developments in FORTRACC included the integration of satellite rainfall retrievals, radar fields and thunderstorm initiation. These improvements try to address the following problems: a) most of the satellite rainfall retrievals do not take into account the life cycle stage that it is a key element on defining the rain area and rain intensity; b) by using the life cycle information it is possible to better predict the precipitation pattern observed in the radar fields; c) cloud signatures are associated to the development of systems that have lightning and no lightning activity. During the presentation, an overview of the different applications of FORTRACC will be presented including case studies and evaluation of the technique. Finally, the presentation will address how the users can have access to the algorithm to implement in their institute.

Toward a mechanistic understanding of the damage evolution of SnAgCu solder joints in accelerated thermal cycling test

NASA Astrophysics Data System (ADS)

Mahin Shirazi, Sam

Accelerated thermal cycling (ATC) tests are the most commonly used tests for the thermo-mechanical performance assessment of microelectronics assemblies. Currently used reliability models have failed to incorporate the microstructural dependency of lead free solder joint behavior and its microstructure evolution during cycling. Thus, it is essential to have a mechanistic understanding of the effect of cycling parameters on damage evolution and failure of lead free solder joints in ATC. Recrystallization has been identified as the damage rate controlling mechanism in ATC. Usually it takes 1/3 of life for completion of recrystallization regardless of cycling parameters. Thus, the life of the solder joints can be predicted by estimating global recrystallization. The objective of the first part of the study was to examine whether the damage scenario applies in service is the same as the harsh thermal cycling tests (i.e. 0/100 °C and -40/125 °C) commonly used in industry. Microstructure analysis results on a variety of lead free solder SnAgCu assemblies subjected to the both harsh (0/100 °C) and mild (20/80 °C) ATC confirmed similar failure mechanism under the both testing conditions. Sn grain morphology (interlaced versus beach ball) has a significant effect on the thermo-mechanical performance (and thus the model) of the lead free solder joints. The longer thermal cycling lifetime observed in the interlaced solder joints subjected to the ATC compared to the beach ball structure was correlated to the different initial microstructure and the microstructure evolution during cycling. For the modeling proposes, the present study was focused on Sn-Ag-Cu solder joints with either a single Sn grain or beach ball structure. Microstructural analysis results of the simulated thermal cycling experiment revealed that, the life can be approximated as determined by the accumulation of a certain amount of work during the high temperature dwells. Finally the effect of precipitates spacing on acceleration factor was investigated. Results indicated that a smaller initial precipitate spacing would tend to result in a longer life in mild thermal cycling/service (where there is lower stresses). Accordingly, it is essential to incorporate the dependence of damage rate (i.e. recrystallization) on precipitate coarsening in any predictions.

Probabilistic framework for product design optimization and risk management

NASA Astrophysics Data System (ADS)

Keski-Rahkonen, J. K.

2018-05-01

Probabilistic methods have gradually gained ground within engineering practices but currently it is still the industry standard to use deterministic safety margin approaches to dimensioning components and qualitative methods to manage product risks. These methods are suitable for baseline design work but quantitative risk management and product reliability optimization require more advanced predictive approaches. Ample research has been published on how to predict failure probabilities for mechanical components and furthermore to optimize reliability through life cycle cost analysis. This paper reviews the literature for existing methods and tries to harness their best features and simplify the process to be applicable in practical engineering work. Recommended process applies Monte Carlo method on top of load-resistance models to estimate failure probabilities. Furthermore, it adds on existing literature by introducing a practical framework to use probabilistic models in quantitative risk management and product life cycle costs optimization. The main focus is on mechanical failure modes due to the well-developed methods used to predict these types of failures. However, the same framework can be applied on any type of failure mode as long as predictive models can be developed.

Completing the cycle: maternal effects as the missing link in plant life histories.

PubMed

Donohue, Kathleen

2009-04-27

Maternal effects on seed traits such as germination are important components of the life histories of plants because they represent the pathway from adult to offspring: the pathway that completes the life cycle. Maternal environmental effects on germination influence basic life-history expression, natural selection on germination, the expression of genetic variation for germination and even the genes involved in germination. Maternal effects on seed traits can even influence generation time and projected population growth rates. Whether these maternal environmental effects are imposed by the maternal genotype, the endosperm genotype or the embryonic genotype, however, is as yet unknown. Patterns of gene expression and protein synthesis in seeds indicate that the maternal genotype has the opportunity to influence its progeny's germination behaviour. Investigation of the phenotypic consequences of maternal environmental effects, regardless of its genetic determination, is relevant for understanding the variation in plant life cycles. Distinguishing the genotype(s) that control them is relevant for predicting the evolutionary trajectories and patterns of selection on progeny phenotypes and the genes underlying them.

Discrete Element Model for Simulations of Early-Life Thermal Fracturing Behaviors in Ceramic Nuclear Fuel Pellets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hai Huang; Ben Spencer; Jason Hales

2014-10-01

A discrete element Model (DEM) representation of coupled solid mechanics/fracturing and heat conduction processes has been developed and applied to explicitly simulate the random initiations and subsequent propagations of interacting thermal cracks in a ceramic nuclear fuel pellet during initial rise to power and during power cycles. The DEM model clearly predicts realistic early-life crack patterns including both radial cracks and circumferential cracks. Simulation results clearly demonstrate the formation of radial cracks during the initial power rise, and formation of circumferential cracks as the power is ramped down. In these simulations, additional early-life power cycles do not lead to themore » formation of new thermal cracks. They do, however clearly indicate changes in the apertures of thermal cracks during later power cycles due to thermal expansion and shrinkage. The number of radial cracks increases with increasing power, which is consistent with the experimental observations.« less

The role of data fusion in predictive maintenance using digital twin

NASA Astrophysics Data System (ADS)

Liu, Zheng; Meyendorf, Norbert; Mrad, Nezih

2018-04-01

Modern aerospace industry is migrating from reactive to proactive and predictive maintenance to increase platform operational availability and efficiency, extend its useful life cycle and reduce its life cycle cost. Multiphysics modeling together with data-driven analytics generate a new paradigm called "Digital Twin." The digital twin is actually a living model of the physical asset or system, which continually adapts to operational changes based on the collected online data and information, and can forecast the future of the corresponding physical counterpart. This paper reviews the overall framework to develop a digital twin coupled with the industrial Internet of Things technology to advance aerospace platforms autonomy. Data fusion techniques particularly play a significant role in the digital twin framework. The flow of information from raw data to high-level decision making is propelled by sensor-to-sensor, sensor-to-model, and model-to-model fusion. This paper further discusses and identifies the role of data fusion in the digital twin framework for aircraft predictive maintenance.

Complex life cycles in a pond food web: effects of life stage structure and parasites on network properties, trophic positions and the fit of a probabilistic niche model.

PubMed

Preston, Daniel L; Jacobs, Abigail Z; Orlofske, Sarah A; Johnson, Pieter T J

2014-03-01

Most food webs use taxonomic or trophic species as building blocks, thereby collapsing variability in feeding linkages that occurs during the growth and development of individuals. This issue is particularly relevant to integrating parasites into food webs because parasites often undergo extreme ontogenetic niche shifts. Here, we used three versions of a freshwater pond food web with varying levels of node resolution (from taxonomic species to life stages) to examine how complex life cycles and parasites alter web properties, the perceived trophic position of organisms, and the fit of a probabilistic niche model. Consistent with prior studies, parasites increased most measures of web complexity in the taxonomic species web; however, when nodes were disaggregated into life stages, the effects of parasites on several network properties (e.g., connectance and nestedness) were reversed, due in part to the lower trophic generality of parasite life stages relative to free-living life stages. Disaggregation also reduced the trophic level of organisms with either complex or direct life cycles and was particularly useful when including predation on parasites, which can inflate trophic positions when life stages are collapsed. Contrary to predictions, disaggregation decreased network intervality and did not enhance the fit of a probabilistic niche model to the food webs with parasites. Although the most useful level of biological organization in food webs will vary with the questions of interest, our results suggest that disaggregating species-level nodes may refine our perception of how parasites and other complex life cycle organisms influence ecological networks.

Creep fatigue life prediction for engine hot section materials (ISOTROPIC)

NASA Technical Reports Server (NTRS)

Nelson, R. S.; Schoendorf, J. F.; Lin, L. S.

1986-01-01

The specific activities summarized include: verification experiments (base program); thermomechanical cycling model; multiaxial stress state model; cumulative loading model; screening of potential environmental and protective coating models; and environmental attack model.

Sequencing the fungal tree of life

Treesearch

F. Martin; D. Cullen; D. Hibbett; A. Pisabarro; J.W. Spatafora; S.E. Baker; I.V. Grigoriev

2011-01-01

Terrestrial ecosystems host a complex array of interacting communities, with thousands of species of animals, plants, fungi and bacteria. In soils, this complex web of life is responsible for the cycling of carbon (C), for water and nutrients, for soil quality and for plant nutrition and health. To predict future changes of these threatened ecosystems and to fully...

Experimental and theoretical investigation of fatigue life in reusable rocket thrust chambers

NASA Technical Reports Server (NTRS)

Hannum, N. P.; Kasper, H. J.; Pavli, A. J.

1976-01-01

During a test program to investigate low-cycle thermal fatigue, 13 rocket combustion chambers were fabricated and cyclically test fired to failure. Six oxygen-free, high-conductivity (OFHC) copper and seven Amzirc chambers were tested. The failures in the OFHC copper chambers were not typical fatigue failures but are described as creep rupture enhanced by ratcheting. The coolant channels bulged toward the chamber centerline, resulting in progressive thinning of the wall during each cycle. The failures in the Amzirc alloy chambers were caused by low-cycle thermal fatigue. The zirconium in this alloy was not evenly distributed in the chamber materials. The life that was achieved was nominally the same as would have been predicted from OFHC copper isothermal test data.

Life-Cycle Cost/Benefit Assessment of Expedite Departure Path (EDP)

NASA Technical Reports Server (NTRS)

Wang, Jianzhong Jay; Chang, Paul; Datta, Koushik

2005-01-01

This report presents a life-cycle cost/benefit assessment (LCCBA) of Expedite Departure Path (EDP), an air traffic control Decision Support Tool (DST) currently under development at NASA. This assessment is an update of a previous study performed by bd Systems, Inc. (bd) during FY01, with the following revisions: The life-cycle cost assessment methodology developed by bd for the previous study was refined and calibrated using Free Flight Phase 1 (FFP1) cost information for Traffic Management Advisor (TMA, or TMA-SC in the FAA's terminology). Adjustments were also made to the site selection and deployment scheduling methodology to include airspace complexity as a factor. This technique was also applied to the benefit extrapolation methodology to better estimate potential benefits for other years, and at other sites. This study employed a new benefit estimating methodology because bd s previous single year potential benefit assessment of EDP used unrealistic assumptions that resulted in optimistic estimates. This methodology uses an air traffic simulation approach to reasonably predict the impacts from the implementation of EDP. The results of the costs and benefits analyses were then integrated into a life-cycle cost/benefit assessment.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pirhonen, P.

Life-cycle assessment is usually based on regular discharges that occur at a more or less constant rate. Nevertheless, the more factors that are taken into account in the LCA the better picture it gives on the environmental aspects of a product. In this study an approach to incorporate accidental releases into a products` life-cycle assessment was developed. In this approach accidental releases are divided into two categories. The first category consists of those unplanned releases which occur with a predicted level and frequency. Due to the high frequency and small release size at a time, these accidental releases can bemore » compared to continuous emissions. Their global impacts are studied in this approach. Accidental releases of the second category are sudden, unplanned releases caused by exceptional situations, e.g. technical failure, action error or disturbances in process conditions. These releases have a singular character and local impacts are typical of them. As far as the accidental releases of the second category are concerned, the approach introduced in this study results in a risk value for every stage of a life-cycle, the sum of which is a risk value for the whole life-cycle. Risk value is based on occurrence frequencies of incidents and potential environmental damage caused by releases. Risk value illustrates the level of potential damage caused by accidental releases related to the system under study and is meant to be used for comparison of these levels of two different products. It can also be used to compare the risk levels of different stages of the life-cycle. An approach was illustrated using petrol as an example product. The whole life-cycle of petrol from crude oil production to the consumption of petrol was studied.« less

Development of a Feedstock-to-Product Chain Model for Densified Biomass Pellets

NASA Astrophysics Data System (ADS)

McPherrin, Daniel

The Q’Pellet is a spherical, torrefied biomass pellet currently under development. It aims to improve on the shortcomings of commercially available cylindrical white and torrefied pellets. A spreadsheet-based model was developed to allow for techno-economic analysis and simplified life cycle analysis of Q’Pellets, torrefied pellets and white pellets. A case study was developed to compare the production of white, torrefied and Q’Pellet production based on their internal rates of return and life cycle greenhouse gas emissions. The case study was based on a commercial scale plant built in Williams Lake BC with product delivery in Rotterdam, Netherlands. Q’Pellets had the highest modelled internal rate of return, at 12.7%, with white pellets at 11.1% and torrefied pellets at 8.0%. The simplified life cycle analysis showed that Q’Pellets had the lowest life cycle greenhouse gas emissions of the three products, 6.96 kgCO2eq/GJ, compared to 21.50 kgCO2eq/GJ for white pellets and 10.08 kgCO2eq/GJ for torrefied pellets. At these levels of life cycle greenhouse gas emissions, white pellets are above the maximum life cycle emissions to be considered sustainable under EU regulations. Sensitivity analysis was performed on the model by modifying input variables, and showed that white pellets are more sensitive to uncontrollable market variables, especially pellet sale prices, raw biomass prices and transportation costs. Monte Carlo analysis was also performed, which showed that white pellet production is less predictable and more likely to lead to a negative internal rate of return compared to Q’Pellet production.

Laser cutting of various materials: Kerf width size analysis and life cycle assessment of cutting process

NASA Astrophysics Data System (ADS)

Yilbas, Bekir Sami; Shaukat, Mian Mobeen; Ashraf, Farhan

2017-08-01

Laser cutting of various materials including Ti-6Al-4V alloy, steel 304, Inconel 625, and alumina is carried out to assess the kerf width size variation along the cut section. The life cycle assessment is carried out to determine the environmental impact of the laser cutting in terms of the material waste during the cutting process. The kerf width size is formulated and predicted using the lump parameter analysis and it is measured from the experiments. The influence of laser output power and laser cutting speed on the kerf width size variation is analyzed using the analytical tools including scanning electron and optical microscopes. In the experiments, high pressure nitrogen assisting gas is used to prevent oxidation reactions in the cutting section. It is found that the kerf width size predicted from the lump parameter analysis agrees well with the experimental data. The kerf width size variation increases with increasing laser output power. However, this behavior reverses with increasing laser cutting speed. The life cycle assessment reveals that material selection for laser cutting is critical for the environmental protection point of view. Inconel 625 contributes the most to the environmental damages; however, recycling of the waste of the laser cutting reduces this contribution.

Novel population genetics in ciliates due to life cycle and nuclear dimorphism.

PubMed

Morgens, David W; Stutz, Timothy C; Cavalcanti, Andre R O

2014-08-01

Our understanding of population genetics comes primarily from studies of organisms with canonical life cycles and nuclear organization, either haploid or diploid, sexual, or asexual. Although this template yields satisfactory results for the study of animals and plants, the wide variety of genomic organizations and life cycles of unicellular eukaryotes can make these organisms behave differently in response to mutation, selection, and drift than predicted by traditional population genetic models. In this study, we show how each of these unique features of ciliates affects their evolutionary parameters in mutation-selection, selection-drift, and mutation-selection-drift situations. In general, ciliates are less efficient in eliminating deleterious mutations-these mutations linger longer and at higher frequencies in ciliate populations than in sexual populations--and more efficient in selecting beneficial mutations. Approaching this problem via analytical techniques and simulation allows us to make specific predictions about the nature of ciliate evolution, and we discuss the implications of these results with respect to the high levels of polymorphism and high rate of protein evolution reported for ciliates. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Elevated temperature biaxial fatigue

NASA Technical Reports Server (NTRS)

Jordan, E. H.

1983-01-01

Biaxial fatigue is often encountered in the complex thermo-mechanical loadings present in gas turbine engines. Engine strain histories can involve non-constant temperature, mean stress, creep, environmental effects, both isotropic and anisotropic materials and non-proportional loading. Life prediction for the general case involving all the above factors is not a practicable research project. The current research program is limited to isothermal fatigue at room temperature and 1200 F of Hastalloy-X for both proportional and non-proportional loading. An improved method for predicting the fatigue life and deformation response under biaxial cycle loading is sought.

Freshwater Harmful Algal Blooms

EPA Pesticide Factsheets

EPA is seeking regular and early career applications proposing innovative research on the prediction, prevention, control and mitigation of freshwater HABs as well as the drivers, life cycle patterns, and fate of and effects from from less-common, less

Multiple Fatigue Failure Behaviors and Long-Life Prediction Approach of Carburized Cr-Ni Steel with Variable Stress Ratio

PubMed Central

Deng, Hailong; Li, Wei; Zhao, Hongqiao; Sakai, Tatsuo

2017-01-01

Axial loading tests with stress ratios R of −1, 0 and 0.3 were performed to examine the fatigue failure behavior of a carburized Cr-Ni steel in the long-life regime from 104 to 108 cycles. Results show that this steel represents continuously descending S-N characteristics with interior inclusion-induced failure under R = −1, whereas it shows duplex S-N characteristics with surface defect-induced failure and interior inclusion-induced failure under R = 0 and 0.3. The increasing tension eliminates the effect of compressive residual stress and promotes crack initiation from the surface or interior defects in the carburized layer. The FGA (fine granular area) formation greatly depends on the number of loading cycles, but can be inhibited by decreasing the compressive stress. Based on the evaluation of the stress intensity factor at the crack tip, the surface and interior failures in the short life regime can be characterized by the crack growth process, while the interior failure with the FGA in the long life regime can be characterized by the crack initiation process. In view of the good agreement between predicted and experimental results, the proposed approach can be well utilized to predict fatigue lives associated with interior inclusion-FGA-fisheye induced failure, interior inclusion-fisheye induced failure, and surface defect induced failure. PMID:28906454

The caligid life cycle: new evidence from Lepeophtheirus elegans reconciles the cycles of Caligus and Lepeophtheirus (Copepoda: Caligidae)

PubMed Central

Venmathi Maran, Balu Alagar; Moon, Seong Yong; Ohtsuka, Susumu; Oh, Sung-Yong; Soh, Ho Young; Myoung, Jung-Goo; Iglikowska, Anna; Boxshall, Geoffrey Allan

2013-01-01

The developmental stages of the sea louse Lepeophtheirus elegans (Copepoda: Caligidae) are described from material collected from marine ranched Korean rockfish, Sebastes schlegelii. In L. elegans, setal number on the proximal segment of the antennule increases from 3 in the copepodid to 27 in the adult. Using the number of setae as a stage marker supports the inference that the post-naupliar phase of the life cycle comprises six stages: copepodid, chalimus I, chalimus II, pre-adult I, pre-adult II, and the adult. We observed variation in body length in both of the chalimus stages which we consider represents an early expression of sexual size dimorphism. We interpret the larger specimens of chalimus I as putative females, and the smaller as putative males; similarly with chalimus II, larger specimens are putative females and the smaller are males. Two patterns of life cycle are currently recognized within the Caligidae but the evidence presented here reconciles the two. We conclude that the typical caligid life cycle comprises only eight stages: two naupliar, one copepodid, and four chalimus stages preceding the adult in Caligus, but with the four chalimus stages represented by two chalimus and two pre-adult stages in Lepeophtheirus. This is a profound change with significant implications for the aquaculture industry, given that lice monitoring protocols include counts of chalimus stages and use temperature to predict when they will moult into the more pathogenic, mobile pre-adults. Lice management strategies must be tailored to the precise life cycle of the parasite. PMID:23647664

Proof test and fatigue crack growth modeling on 2024-T3 aluminum alloy

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.; Poe, C. C., Jr.; Dawicke, D. S.

1990-01-01

Pressure proof testing of aircraft fuselage structures has been suggested as a means of screening critical crack sizes and of extending their useful life. The objective of this paper is to study the proof-test concept and to model the crack-growth process on a ductile material. Simulated proof and operational fatigue life tests have been conducted on cracked panels made of 2024-T3 aluminum alloy sheet material. A fatigue crack-closure model was modified to simulate the proof test and operational fatigue cycling. Using crack-growth rate and resistance-curve data, the model was able to predict crack growth during and after the proof load. These tests and analyses indicate that the proof test increases fatigue life; but the beneficial life, after a 1.33 or 1.5 proof, was less than a few hundred cycles.

High-cycle fatigue characterization of titanium 5Al-2.5Sn alloy

NASA Technical Reports Server (NTRS)

Mahfuz, H.; Xin, Yu T.; Jeelani, S.

1993-01-01

High-cycle fatigue behavior of titanium 5Al 2.5Sn alloy at room temperature has been studied. S-N curve characterization is performed at different stress ratios ranging from 0 to 0.9 on a subsized fatigue specimen. Both two-stress and three-stress level tests are conducted at different stress ratios to study the cumulative fatigue damage. Life prediction techniques of linear damage rule, double linear damage rule and damage curve approaches are applied, and results are compared with the experimental data. The agreement between prediction and experiment is found to be excellent.

Defining clogging potential for permeable concrete.

PubMed

Kia, Alalea; Wong, Hong S; Cheeseman, Christopher R

2018-08-15

Permeable concrete is used to reduce urban flooding as it allows water to flow through normally impermeable infrastructure. It is prone to clogging by particulate matter and predicting the long-term performance of permeable concrete is challenging as there is currently no reliable means of characterising clogging potential. This paper reports on the performance of a range of laboratory-prepared and commercial permeable concretes, close packed glass spheres and aggregate particles of varying size, exposed to different clogging methods to understand this phenomena. New methods were developed to study clogging and define clogging potential. The tests involved applying flowing water containing sand and/or clay in cycles, and measuring the change in permeability. Substantial permeability reductions were observed in all samples, particularly when exposed to sand and clay simultaneously. Three methods were used to define clogging potential based on measuring the initial permeability decay, half-life cycle and number of cycles to full clogging. We show for the first time strong linear correlations between these parameters for a wide range of samples, indicating their use for service-life prediction. Copyright © 2018 Elsevier Ltd. All rights reserved.

Micromechanisms of thermomechanical fatigue: A comparison with isothermal fatigue

NASA Technical Reports Server (NTRS)

Bill, R. C.

1986-01-01

Thermomechanical Fatigue (TMF) experiments were conducted on Mar-M 200, B-1900, and PWA-1480 (single crystals) over temperature ranges representative of gas turbine airfoil environments. The results were examined from both a phenomenological basis and a micromechanical basis. Depending on constituents present in the superalloy system, certain micromechanisms dominated the crack initiation process and significantly influenced the TMF lives as well as sensitivity of the material to the type TMF cycle imposed. For instance, high temperature cracking around grain boundary carbides in Mar-M 200 resulted in short in-phase TMF lives compared to either out-of-phase or isothermal lives. In single crystal PWA-1480, the type of coating applied was seen to be the controlling factor in determining sensitivity to the type of TMF cycle imposed. Micromechanisms of deformation were observed over the temperature range of interest to the TMF cycles, and provided some insight as to the differences between TMF damage mechanisms and isothermal damage mechanisms. Finally, the applicability of various life prediction models to TMF results was reviewed. Current life prediction models based on isothermal data must be modified before being generally applied to TMF.

Characterization of the temperature evolution during high-cycle fatigue of the ULTIMET superalloy: Experiment and theoretical modeling

NASA Astrophysics Data System (ADS)

Jiang, L.; Wang, H.; Liaw, P. K.; Brooks, C. R.; Klarstrom, D. L.

2001-09-01

High-speed, high-resolution infrared thermography, as a noncontact, full-field, and nondestructive technique, was used to study the temperature variations of a cobalt-based ULTIMET alloy subjected to high-cycle fatigue. During each fatigue cycle, the temperature oscillations, which were due to the thermal-elastic-plastic effects, were observed and related to stress-strain analyses. A constitutive model was developed for predicting the thermal and mechanical responses of the ULTIMET alloy subjected to cyclic deformation. The model was constructed in light of internal-state variables, which were developed to characterize the inelastic strain of the material during cyclic loading. The predicted stress-strain and temperature responses were found to be in good agreement with the experimental results. In addition, the change of temperature during fatigue was employed to reveal the accumulation of fatigue damage, and the measured temperature was utilized as an index for fatigue-life prediction.

TTK Chitra tilting disc heart valve model TC2: An assessment of fatigue life and durability.

PubMed

Subhash, N N; Rajeev, Adathala; Sujesh, Sreedharan; Muraleedharan, C V

2017-08-01

Average age group of heart valve replacement in India and most of the Third World countries is below 30 years. Hence, the valve for such patients need to be designed to have a service life of 50 years or more which corresponds to 2000 million cycles of operation. The purpose of this study was to assess the structural performance of the TTK Chitra tilting disc heart valve model TC2 and thereby address its durability. The TC2 model tilting disc heart valves were assessed to evaluate the risks connected with potential structural failure modes. To be more specific, the studies covered the finite element analysis-based fatigue life prediction and accelerated durability testing of the tilting disc heart valves for nine different valve sizes. First, finite element analysis-based fatigue life prediction showed that all nine valve sizes were in the infinite life region. Second, accelerated durability test showed that all nine valve sizes remained functional for 400 million cycles under experimental conditions. The study ensures the continued function of TC2 model tilting disc heart valves over duration in excess of 50 years. The results imply that the TC2 model valve designs are structurally safe, reliable and durable.

The numerical high cycle fatigue damage model of fillet weld joint under weld-induced residual stresses

NASA Astrophysics Data System (ADS)

Nguyen Van Do, Vuong

2018-04-01

In this study, a development of nonlinear continuum damage mechanics (CDM) model for multiaxial high cycle fatigue is proposed in which the cyclic plasticity constitutive model has been incorporated in the finite element (FE) framework. T-joint FE simulation of fillet welding is implemented to characterize sequentially coupled three-dimensional (3-D) of thermo-mechanical FE formulation and simulate the welding residual stresses. The high cycle fatigue damage model is then taken account into the fillet weld joints under the various cyclic fatigue load types to calculate the fatigue life considering the residual stresses. The fatigue crack initiation and the propagation in the present model estimated for the total fatigue is compared with the experimental results. The FE results illustrated that the proposed high cycle fatigue damage model in this study could become a powerful tool to effectively predict the fatigue life of the welds. Parametric studies in this work are also demonstrated that the welding residual stresses cannot be ignored in the computation of the fatigue life of welded structures.

Method of Fatigue-Life Prediction for an Asphalt Mixture Based on the Plateau Value of Permanent Deformation Ratio.

PubMed

Sun, Yazhen; Fang, Chenze; Wang, Jinchang; Yuan, Xuezhong; Fan, Dong

2018-05-03

Laboratory predictions for the fatigue life of an asphalt mixture under cyclic loading based on the plateau value (PV) of the permanent deformation ratio (PDR) were carried out by three-point bending fatigue tests. The influence of test conditions on the recovery ratio of elastic deformation (RRED), the permanent deformation (PD) and PDR, and the trends of RRED, PD, and PDR were studied. The damage variable was defined by using PDR, and the relation of the fatigue life to PDR was determined by analyzing the damage evolution process. The fatigue equation was established based on the PV of PDR and the fatigue life was predicted by analyzing the relation of the fatigue life to the PV. The results show that the RRED decreases with the increase of the number of loading cycles, and the elastic recovery ability of the asphalt mixture gradually decreases. The two mathematical models proposed are based on the change laws of the RRED, and the PD can well describe the change laws. The RRED or the PD cannot well predict the fatigue life because they do not change monotonously with the fatigue life, and one part of the deformation causes the damage and the other part causes the viscoelastic deformation. The fatigue life decreases with the increase of the PDR. The average PDR in the second stage is taken as the PV, and the fatigue life decreases in a power law with the increase of the PV. The average relative error of the fatigue life predicted by the fatigue equation to the test fatigue life is 5.77%. The fatigue equation based on PV can well predict the fatigue life.

Accelerated life assessment of coating on the radar structure components in coastal environment.

PubMed

Liu, Zhe; Ming, ZhiMao

2016-07-04

This paper aimed to build an accelerated life test scheme and carry out quantitative analysis between accelerated life test in the laboratory and actual service for the coating composed of epoxy primer and polyurethane paint on structure components of some kind of radar served in the coastal environment of South China Sea. The accelerated life test scheme was built based on the service environment and failure analysis of the coating. The quantitative analysis between accelerated life test and actual service was conducted by comparing the gloss loss, discoloration, chalking, blistering, cracking and electrochemical impedance spectroscopy of the coating. The main factors leading to the coating failure were ultraviolet radiation, temperature, moisture, salt fog and loads, the accelerated life test included ultraviolet radiation, damp heat, thermal shock, fatigue and salt spray. The quantitative relationship was that one cycle of the accelerated life test was equal to actual service for one year. It was established that one cycle of the accelerated life test was equal to actual service for one year. It provided a precise way to predict actual service life of newly developed coatings for the manufacturer.

How rare is complex life in the Milky Way?

PubMed

Bounama, Christine; von Bloh, Werner; Franck, Siegfried

2007-10-01

An integrated Earth system model was applied to calculate the number of habitable Earth-analog planets that are likely to have developed primitive (unicellular) and complex (multicellular) life in extrasolar planetary systems. The model is based on the global carbon cycle mediated by life and driven by increasing stellar luminosity and plate tectonics. We assumed that the hypothetical primitive and complex life forms differed in their temperature limits and CO(2) tolerances. Though complex life would be more vulnerable to environmental stress, its presence would amplify weathering processes on a terrestrial planet. The model allowed us to calculate the average number of Earth-analog planets that may harbor such life by using the formation rate of Earth-like planets in the Milky Way as well as the size of a habitable zone that could support primitive and complex life forms. The number of planets predicted to bear complex life was found to be approximately 2 orders of magnitude lower than the number predicted for primitive life forms. Our model predicted a maximum abundance of such planets around 1.8 Ga ago and allowed us to calculate the average distance between potentially habitable planets in the Milky Way. If the model predictions are accurate, the future missions DARWIN (up to a probability of 65%) and TPF (up to 20%) are likely to detect at least one planet with a biosphere composed of complex life.

NCCLCS: LIFE CYCLE OF NANOMATERIALS (LCNANO)

EPA Science Inventory

Because engineered nanomaterials (NMs) have transformative benefits to individuals and society, they are being incorporated into many products. However, tremendous uncertainty presently exists in our ability to predict or manage risks from nano-enabled products across their...

Economic impacts of electric vehicle adoption.

DOT National Transportation Integrated Search

2017-02-01

The objective of the Economic Impacts of Electric Vehicle Adoption research project was to : examine the predicted levels of electric vehicle (EV) adoption, to analyze the life cycle costs of : EVs compared to internal combustion engine vehicles and ...

Projecting LED product life based on application

NASA Astrophysics Data System (ADS)

Narendran, Nadarajah; Liu, Yi-wei; Mou, Xi; Thotagamuwa, Dinusha R.; Eshwarage, Oshadhi V. Madihe

2016-09-01

LED products have started to displace traditional light sources in many lighting applications. One of the commonly claimed benefits for LED lighting products is their long useful lifetime in applications. Today there are many replacement lamp products using LEDs in the marketplace. Typically, lifetime claims of these replacement lamps are in the 25,000-hour range. According to current industry practice, the time for the LED light output to reach the 70% value is estimated according to IESNA LM-80 and TM-21 procedures and the resulting value is reported as the whole system life. LED products generally experience different thermal environments and switching (on-off cycling) patterns when used in applications. Current industry test methods often do not produce accurate lifetime estimates for LED systems because only one component of the system, namely the LED, is tested under a continuous-on burning condition without switching on and off, and because they estimate for only one failure type, lumen depreciation. The objective of the study presented in this manuscript was to develop a test method that could help predict LED system life in any application by testing the whole LED system, including on-off power cycling with sufficient dwell time, and considering both failure types, catastrophic and parametric. The study results showed for the LED A-lamps tested in this study, both failure types, catastrophic and parametric, exist. The on-off cycling encourages catastrophic failure, and maximum operating temperature influences the lumen depreciation rate and parametric failure time. It was also clear that LED system life is negatively affected by on-off switching, contrary to commonly held belief. In addition, the study results showed that most of the LED systems failed catastrophically much ahead of the LED light output reaching the 70% value. This emphasizes the fact that life testing of LED systems must consider catastrophic failure in addition to lumen depreciation, and the shorter of the two failure modes must be selected as the system life. The results of this study show a shorter time test procedure can be developed to accurately predict LED system life in any application by knowing the LED temperature and the switching cycle.

Ductility normalized-strainrange partitioning life relations for creep-fatigue life predictions

NASA Technical Reports Server (NTRS)

Halford, G. R.; Saltsman, J. F.; Hirschberg, M. H.

1977-01-01

Procedures based on Strainrange Partitioning (SRP) are presented for estimating the effects of environment and other influences on the high temperature, low cycle, creep fatigue resistance of alloys. It is proposed that the plastic and creep, ductilities determined from conventional tensile and creep rupture tests conducted in the environment of interest be used in a set of ductility normalized equations for making a first order approximation of the four SRP inelastic strainrange life relations. Different levels of sophistication in the application of the procedures are presented by means of illustrative examples with several high temperature alloys. Predictions of cyclic lives generally agree with observed lives within factors of three.

Above-knee prosthesis design based on fatigue life using finite element method and design of experiment.

PubMed

Phanphet, Suwattanarwong; Dechjarern, Surangsee; Jomjanyong, Sermkiat

2017-05-01

The main objective of this work is to improve the standard of the existing design of knee prosthesis developed by Thailand's Prostheses Foundation of Her Royal Highness The Princess Mother. The experimental structural tests, based on the ISO 10328, of the existing design showed that a few components failed due to fatigue under normal cyclic loading below the required number of cycles. The finite element (FE) simulations of structural tests on the knee prosthesis were carried out. Fatigue life predictions of knee component materials were modeled based on the Morrow's approach. The fatigue life prediction based on the FE model result was validated with the corresponding structural test and the results agreed well. The new designs of the failed components were studied using the design of experimental approach and finite element analysis of the ISO 10328 structural test of knee prostheses under two separated loading cases. Under ultimate loading, knee prosthesis peak von Mises stress must be less than the yield strength of knee component's material and the total knee deflection must be lower than 2.5mm. The fatigue life prediction of all knee components must be higher than 3,000,000 cycles under normal cyclic loading. The design parameters are the thickness of joint bars, the diameter of lower connector and the thickness of absorber-stopper. The optimized knee prosthesis design meeting all the requirements was recommended. Experimental ISO 10328 structural test of the fabricated knee prosthesis based on the optimized design confirmed the finite element prediction. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

An Update on the Lithium-Ion Cell Low-Earth-Orbit Verification Test Program

NASA Technical Reports Server (NTRS)

Reid, Concha M.; Manzo, Michelle A.; Miller, Thomas B.; McKissock, Barbara I.; Bennett, William

2007-01-01

A Lithium-Ion Cell Low-Earth-Orbit Verification Test Program is being conducted by NASA Glenn Research Center to assess the performance of lithium-ion (Li-ion) cells over a wide range of low-Earth-orbit (LEO) conditions. The data generated will be used to build an empirical model for Li-ion batteries. The goal of the modeling will be to develop a tool to predict the performance and cycle life of Li-ion batteries operating at a specified set of mission conditions. Using this tool, mission planners will be able to design operation points of the battery system while factoring in mission requirements and the expected life and performance of the batteries. Test conditions for the program were selected via a statistical design of experiments to span a range of feasible operational conditions for LEO aerospace applications. The variables under evaluation are temperature, depth-of-discharge (DOD), and end-of-charge voltage (EOCV). The baseline matrix was formed by generating combinations from a set of three values for each variable. Temperature values are 10 C, 20 C and 30 C. Depth-of-discharge values are 20%, 30% and 40%. EOCV values are 3.85 V, 3.95 V, and 4.05 V. Test conditions for individual cells may vary slightly from the baseline test matrix depending upon the cell manufacturer s recommended operating conditions. Cells from each vendor are being evaluated at each of ten sets of test conditions. Cells from four cell manufacturers are undergoing life cycle tests. Life cycling on the first sets of cells began in September 2004. These cells consist of Saft 40 ampere-hour (Ah) cells and Lith ion 30 Ah cells. These cells have achieved over 10,000 cycles each, equivalent to about 20 months in LEO. In the past year, the test program has expanded to include the evaluation of Mine Safety Appliances (MSA) 50 Ah cells and ABSL battery modules. The MSA cells will begin life cycling in October 2006. The ABSL battery modules consist of commercial Sony hard carbon 18650 lithium-ion cells configured in series and parallel combinations to create nominal 14.4 volt, 3 Ah packs (4s-2p). These modules have accumulated approximately 3000 cycles. Results on the performance of the cells and modules will be presented in this paper. The life prediction and performance model for Li-ion cells in LEO will be built by analyzing the data statistically and performing regression analysis. Cells are being cycled to failure so that differences in performance trends that occur at different stages in the life of the cell can be observed and accurately modeled. Cell testing is being performed at the Naval Surface Warfare Center in Crane, IN.

Effects of Coatings on the High-Cycle Fatigue Life of Threaded Steel Samples

NASA Astrophysics Data System (ADS)

Eder, M. A.; Haselbach, P. U.; Mishin, O. V.

2018-05-01

In this work, high-cycle fatigue is studied for threaded cylindrical high-strength steel samples coated using three different industrial processes: black oxidation, normal-temperature galvanization and high-temperature galvanization. The fatigue performance in air is compared with that of uncoated samples. Microstructural characterization revealed the abundant presence of small cracks in the zinc coating partially penetrating into the steel. This is consistent with the observation of multiple crack initiation sites along the thread in the galvanized samples, which led to crescent type fracture surfaces governed by circumferential growth. In contrast, the black oxidized and uncoated samples exhibited a semicircular segment type fracture surface governed by single-sided growth with a significantly longer fatigue life. Numerical fatigue life prediction based on an extended Paris-law formulation has been conducted on two different fracture cases: 2D axisymmetric multisided crack growth and 3D single-sided crack growth. The results of this upper-bound and lower-bound approach are in good agreement with experimental data and can potentially be used to predict the lifetime of bolted components.

Notched fatigue of single crystal PWA 1480 at turbine attachment temperatures

NASA Technical Reports Server (NTRS)

Meyer, T. G.; Nissley, D. M.; Swanson, G. A.

1989-01-01

The focus is on the lower temperature, uncoated and notched features of gas turbine blades. Constitutive and fatigue life prediction models applicable to these regions are being developed. Fatigue results are presented which were obtained thus far. Fatigue tests are being conducted on PWA 1480 single crystal material using smooth strain controlled specimens and three different notched specimens. Isothermal fatigue tests were conducted at 1200, 1400, and 1600 F. The bulk of the tests were conducted at 1200 F. The strain controlled tests were conducted at 0.4 percent per second strain rate and the notched tests were cycled at 1.0 cycle per second. A clear orientation dependence is observed in the smooth strain controlled fatigue results. The fatigue lifes of the thin, mild notched specimens agree fairly well with this smooth data when elastic stress range is used as a correlating parameter. Finite element analyses were used to calculate notch stresses. Fatigue testing will continue to further explore the trends observed thus far. Constitutive and life prediction models are being developed.

Damage Evolution and Life Prediction of Cross-Ply C/SiC Ceramic-Matrix Composite under Cyclic Fatigue Loading at Room Temperature and 800 °C in Air

PubMed Central

Li, Longbiao

2015-01-01

The damage evolution and life prediction of cross-ply C/SiC ceramic-matrix composite (CMC) under cyclic-fatigue loading at room temperature and 800 °C in air have been investigated using damage parameters derived from fatigue hysteresis loops, i.e., fatigue hysteresis modulus and fatigue hysteresis loss energy. The experimental fatigue hysteresis modulus and fatigue hysteresis loss energy degrade with increasing applied cycles attributed to transverse cracks in the 90° plies, matrix cracks and fiber/matrix interface debonding in the 0° plies, interface wear at room temperature, and interface and carbon fibers oxidation at 800 °C in air. The relationships between fatigue hysteresis loops, fatigue hysteresis modulus and fatigue hysteresis loss energy have been established. Comparing experimental fatigue hysteresis loss energy with theoretical computational values, the fiber/matrix interface shear stress corresponding to different cycle numbers has been estimated. It was found that the degradation rate at 800 °C in air is much faster than that at room temperature due to serious oxidation in the pyrolytic carbon (PyC) interphase and carbon fibers. Combining the fiber fracture model with the interface shear stress degradation model and the fibers strength degradation model, the fraction of broken fibers versus the cycle number can be determined for different fatigue peak stresses. The fatigue life S-N curves of cross-ply C/SiC composite at room temperature and 800 °C in air have been predicted. PMID:28793728

Damage Evolution and Life Prediction of Cross-Ply C/SiC Ceramic-Matrix Composite under Cyclic Fatigue Loading at Room Temperature and 800 °C in Air.

PubMed

Li, Longbiao

2015-12-09

The damage evolution and life prediction of cross-ply C/SiC ceramic-matrix composite (CMC) under cyclic-fatigue loading at room temperature and 800 °C in air have been investigated using damage parameters derived from fatigue hysteresis loops, i.e. , fatigue hysteresis modulus and fatigue hysteresis loss energy. The experimental fatigue hysteresis modulus and fatigue hysteresis loss energy degrade with increasing applied cycles attributed to transverse cracks in the 90° plies, matrix cracks and fiber/matrix interface debonding in the 0° plies, interface wear at room temperature, and interface and carbon fibers oxidation at 800 °C in air. The relationships between fatigue hysteresis loops, fatigue hysteresis modulus and fatigue hysteresis loss energy have been established. Comparing experimental fatigue hysteresis loss energy with theoretical computational values, the fiber/matrix interface shear stress corresponding to different cycle numbers has been estimated. It was found that the degradation rate at 800 °C in air is much faster than that at room temperature due to serious oxidation in the pyrolytic carbon (PyC) interphase and carbon fibers. Combining the fiber fracture model with the interface shear stress degradation model and the fibers strength degradation model, the fraction of broken fibers versus the cycle number can be determined for different fatigue peak stresses. The fatigue life S-N curves of cross-ply C/SiC composite at room temperature and 800 °C in air have been predicted.

Oxidation and low cycle fatigue life prediction

NASA Technical Reports Server (NTRS)

Oshida, Y.; Liu, H. W.

1984-01-01

When a metallic material is exposed to a high temperature in an ambient atmosphere, oxidation takes place on the metallic surface. The formed oxides (both surface and grain boundary oxides) are mechanically brittle so that if the stress is high enough the oxides will be cracked. The grain boundary oxide formation in TAZ-8A nickel-base superalloy was studied. The effect of oxide crack nucleus on low cycle fatigue life will be analyzed. The TAZ-8A was subjected to high temperature oxidation tests in air under the stress-free condition. The oxidation temperatures were 600, 800, and 1000 C. The oxidation time varies from 10 to 1000 hours.

Synergistic Effects of Temperature, Oxidation and Multicracking Modes on Damage Evolution and Life Prediction of 2D Woven Ceramic-Matrix Composites under Tension-Tension Fatigue Loading

NASA Astrophysics Data System (ADS)

Longbiao, Li

2017-08-01

In this paper, the synergistic effects of temperature, oxidation and multicracking modes on damage evolution and life prediction in 2D woven ceramic-matrix composites (CMCs) have been investigated. The damage parameter of fatigue hysteresis dissipated energy and the interface shear stress were used to monitor the damage evolution inside of CMCs. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface/fiber oxidation model, interface wear model and fibers statistical failure model at elevated temperature, based on the assumption that the fiber strength is subjected to two-parameter Weibull distribution and the load carried by broken and intact fibers satisfy the Global Load Sharing (GLS) criterion. When the broken fibers fraction approaches to the critical value, the composite fatigue fractures. The evolution of fatigue hysteresis dissipated energy, the interface shear stress and broken fibers fraction versus cycle number, and the fatigue life S-N curves of SiC/SiC at 1000, 1200 and 1300 °C in air and steam condition have been predicted. The synergistic effects of temperature, oxidation, fatigue peak stress, and multicracking modes on the evolution of interface shear stress and fatigue hysteresis dissipated energy versus cycle numbers curves have been analyzed.

Life cycle development of obesity and its determinants in six European countries.

PubMed

Cavaco, Sandra; Eriksson, Tor; Skalli, Ali

2014-07-01

This paper empirically examines the effect of parents' and individuals' own socioeconomic status on overweight and obesity, and investigates how this effect changes over the life cycle. The impact of individuals' health behaviours on their obesity status later in life is also studied. We use data from Denmark, Finland, France, Greece, the Netherlands and the U.K. in which 4595 individuals aged 50-65 are surveyed and where individuals' height and weight at different ages (25, 35, 45 and current age) are available. We perform "repeated cross-sections" analyses as well as dynamic probit analyses of the individuals' obesity histories. We contribute to the literature by examining the role of a variety of obesity determinants over the whole life cycle, not only over a certain portion of individuals' lives. Key findings are: (i) parents' socioeconomic status predicts obesity in early adulthood whereas the individual's own socioeconomic status as adult is more important in explaining obesity at later stages of the life cycle, (ii) changes in obesity status are associated with changes in health behaviours, (iii) obesity in late adulthood is strongly and positively correlated with overweight and obesity in younger ages, and (iv) cross-country differences in obesity and overweight largely remain after controlling for parental and childhood factors and individuals' health behaviours. Copyright © 2014 Elsevier B.V. All rights reserved.

Is There a Tectonically Driven Supertidal Cycle?

NASA Astrophysics Data System (ADS)

Green, J. A. M.; Molloy, J. L.; Davies, H. S.; Duarte, J. C.

2018-04-01

Earth is 180 Myr into the current supercontinent cycle, and the next supercontinent is predicted to form in 250 Myr. The continuous changes in continental configuration can move the ocean between resonant states, and the semidiurnal tides are currently large compared to the past 252 Myr due to tidal resonance in the Atlantic. This leads to the hypothesis that there is a "supertidal" cycle linked to the supercontinent cycle. Here this is tested using new tectonic predictions for the next 250 Myr as bathymetry in a numerical tidal model. The simulations support the following hypothesis: a new tidal resonance will appear 150 Myr from now, followed by a decreasing tide as the supercontinent forms 100 Myr later. This affects the dissipation of tidal energy in the oceans, with consequences for the evolution of the Earth-Moon system, ocean circulation and climate, and implications for the ocean's capacity of hosting and evolving life.

Damage-based life prediction model for uniaxial low-cycle stress fatigue of super-elastic NiTi shape memory alloy microtubes

NASA Astrophysics Data System (ADS)

Song, Di; Kang, Guozheng; Kan, Qianhua; Yu, Chao; Zhang, Chuanzeng

2015-08-01

Based on the experimental observations for the uniaxial low-cycle stress fatigue failure of super-elastic NiTi shape memory alloy microtubes (Song et al 2015 Smart Mater. Struct. 24 075004) and a new definition of damage variable corresponding to the variation of accumulated dissipation energy, a phenomenological damage model is proposed to describe the damage evolution of the NiTi microtubes during cyclic loading. Then, with a failure criterion of Dc = 1, the fatigue lives of the NiTi microtubes are predicted by the damage-based model, the predicted lives are in good agreement with the experimental ones, and all of the points are located within an error band of 1.5 times.

Isothermal and thermal-mechanical fatigue of VVER-440 reactor pressure vessel steels

NASA Astrophysics Data System (ADS)

Fekete, Balazs; Trampus, Peter

2015-09-01

The fatigue life of the structural materials 15Ch2MFA (CrMoV-alloyed ferritic steel) and 08Ch18N10T (CrNi-alloyed austenitic steel) of VVER-440 reactor pressure vessel under completely reserved total strain controlled low cycle fatigue tests were investigated. An advanced test facility was developed for GLEEBLE-3800 physical simulator which was able to perform thermomechanical fatigue experiments under in-service conditions of VVER nuclear reactors. The low cycle fatigue results were evaluated with the plastic strain based Coffin-Manson law, and plastic strain energy based model as well. It was shown that both methods are able to predict the fatigue life of reactor pressure vessel steels accurately. Interrupted fatigue tests were also carried out to investigate the kinetic of the fatigue evolution of the materials. On these samples microstructural evaluation by TEM was performed. The investigated low cycle fatigue behavior can provide reference for remaining life assessment and lifetime extension analysis.

Advanced ceramic coating development for industrial/utility gas turbine applications

NASA Technical Reports Server (NTRS)

Andersson, C. A.; Lau, S. K.; Bratton, R. J.; Lee, S. Y.; Rieke, K. L.; Allen, J.; Munson, K. E.

1982-01-01

The effects of ceramic coatings on the lifetimes of metal turbine components and on the performance of a utility turbine, as well as of the turbine operational cycle on the ceramic coatings were determined. When operating the turbine under conditions of constant cooling flow, the first row blades run 55K cooler, and as a result, have 10 times the creep rupture life, 10 times the low cycle fatigue life and twice the corrosion life with only slight decreases in both specific power and efficiency. When operating the turbine at constant metal temperature and reduced cooling flow, both specific power and efficiency increases, with no change in component lifetime. The most severe thermal transient of the turbine causes the coating bond stresses to approach 60% of the bond strengths. Ceramic coating failures was studied. Analytic models based on fracture mechanics theories, combined with measured properties quantitatively assessed both single and multiple thermal cycle failures which allowed the prediction of coating lifetime. Qualitative models for corrosion failures are also presented.

Hubble Space Telescope Battery Capacity Update

NASA Technical Reports Server (NTRS)

Hollandsworth, Roger; Armantrout, Jon; Rao, Gopalakrishna M.

2007-01-01

Orbital battery performance for the Hubble Space Telescope is discussed and battery life is predicted which supports decision to replace orbital batteries by 2009-2010 timeframe. Ground characterization testing of cells from the replacement battery build is discussed, with comparison of data from battery capacity characterization with cell studies of Cycle Life and 60% Stress Test at the Naval Weapons Surface Center (NWSC)-Crane, and cell Cycle Life testing at the Marshal Space Flight Center (MSFC). The contents of this presentation includes an update to the performance of the on-orbit batteries, as well as a discussion of the HST Service Mission 4 (SM4) batteries manufactured in 1996 and activated in 2000, and a second set of SM4 backup replacement batteries which began manufacture Jan 11, 2007, with delivery scheduled for July 2008.

Examining Menstrual Tracking to Inform the Design of Personal Informatics Tools

PubMed Central

Epstein, Daniel A.; Lee, Nicole B.; Kang, Jennifer H.; Agapie, Elena; Schroeder, Jessica; Pina, Laura R.; Fogarty, James; Kientz, Julie A.; Munson, Sean A.

2017-01-01

We consider why and how women track their menstrual cycles, examining their experiences to uncover design opportunities and extend the field's understanding of personal informatics tools. To understand menstrual cycle tracking practices, we collected and analyzed data from three sources: 2,000 reviews of popular menstrual tracking apps, a survey of 687 people, and follow-up interviews with 12 survey respondents. We find that women track their menstrual cycle for varied reasons that include remembering and predicting their period as well as informing conversations with healthcare providers. Participants described six methods of tracking their menstrual cycles, including use of technology, awareness of their premenstrual physiological states, and simply remembering. Although women find apps and calendars helpful, these methods are ineffective when predictions of future menstrual cycles are inaccurate. Designs can create feelings of exclusion for gender and sexual minorities. Existing apps also generally fail to consider life stages that women experience, including young adulthood, pregnancy, and menopause. Our findings encourage expanding the field's conceptions of personal informatics. PMID:28516176

Gamma Radiation Sterilization Reduces the High-cycle Fatigue Life of Allograft Bone.

PubMed

Islam, Anowarul; Chapin, Katherine; Moore, Emily; Ford, Joel; Rimnac, Clare; Akkus, Ozan

2016-03-01

Sterilization by gamma radiation impairs the mechanical properties of bone allografts. Previous work related to radiation-induced embrittlement of bone tissue has been limited mostly to monotonic testing which does not necessarily predict the high-cycle fatigue life of allografts in vivo. We designed a custom rotating-bending fatigue device to answer the following questions: (1) Does gamma radiation sterilization affect the high-cycle fatigue behavior of cortical bone; and (2) how does the fatigue life change with cyclic stress level? The high-cycle fatigue behavior of human cortical bone specimens was examined at stress levels related to physiologic levels using a custom-designed rotating-bending fatigue device. Test specimens were distributed among two treatment groups (n = 6/group); control and irradiated. Samples were tested until failure at stress levels of 25, 35, and 45 MPa. At 25 MPa, 83% of control samples survived 30 million cycles (run-out) whereas 83% of irradiated samples survived only 0.5 million cycles. At 35 MPa, irradiated samples showed an approximately 19-fold reduction in fatigue life compared with control samples (12.2 × 10(6) ± 12.3 × 10(6) versus 6.38 × 10(5) ± 6.81 × 10(5); p = 0.046), and in the case of 45 MPa, this reduction was approximately 17.5-fold (7.31 × 10(5) ± 6.39 × 10(5) versus 4.17 × 10(4) ± 1.91 × 10(4); p = 0.025). Equations to estimate high-cycle fatigue life of irradiated and control cortical bone allograft at a certain stress level were derived. Gamma radiation sterilization severely impairs the high cycle fatigue life of structural allograft bone tissues, more so than the decline that has been reported for monotonic mechanical properties. Therefore, clinicians need to be conservative in the expectation of the fatigue life of structural allograft bone tissues. Methods to preserve the fatigue strength of nonirradiated allograft bone tissue are needed. As opposed to what monotonic tests might suggest, the cyclic fatigue life of radiation-sterilized structural allografts is likely severely compromised relative to the nonirradiated condition and therefore should be taken into consideration. Methods to reduce the effect of irradiation or to recover structural allograft bone tissue fatigue strength are important to pursue.

Review of the Agard S&M panel evaluation program of the NASA-Lewis 'SRP' approach to high-temperature LCF life prediction. [Strainrange Partitioning for Low Cycle Fatigue

NASA Technical Reports Server (NTRS)

Hirschberg, M. H.

1978-01-01

Twenty laboratories in six countries participated in this program, each testing its own materials of interest under its own laboratory conditions. In this way the results obtained provided validation of the Strainrange Partitioning (SRP) method for a wide range of materials and insured maximum usefulness to each of the participating laboratories. The first, very necessary step in the evaluation of any life prediction approach - assessing the ability of the method to predict life of simple laboratory specimens subjected to complex loading, was thereby taken. The culmination of this program was the Specialists Meeting that was held in Aalborg, Denmark in April of 1978. At that meeting the various investigators shared their findings, thus providing the basis for an in-depth evaluation of the SRP method. While the results were variable from laboratory to laboratory, most investigators agreed that the SRP method was a significant step toward life prediction in the presence of high temperature and cyclic stresses.

Plasmodium cysteine repeat modular proteins 1-4: complex proteins with roles throughout the malaria parasite life cycle.

PubMed

Thompson, Joanne; Fernandez-Reyes, Delmiro; Sharling, Lisa; Moore, Sally G; Eling, Wijnand M; Kyes, Sue A; Newbold, Christopher I; Kafatos, Fotis C; Janse, Chris J; Waters, Andrew P

2007-06-01

The Cysteine Repeat Modular Proteins (PCRMP1-4) of Plasmodium, are encoded by a small gene family that is conserved in malaria and other Apicomplexan parasites. They are very large, predicted surface proteins with multipass transmembrane domains containing motifs that are conserved within families of cysteine-rich, predicted surface proteins in a range of unicellular eukaryotes, and a unique combination of protein-binding motifs, including a >100 kDa cysteine-rich modular region, an epidermal growth factor-like domain and a Kringle domain. PCRMP1 and 2 are expressed in life cycle stages in both the mosquito and vertebrate. They colocalize with PfEMP1 (P. falciparum Erythrocyte Membrane Antigen-1) during its export from P. falciparum blood-stage parasites and are exposed on the surface of haemolymph- and salivary gland-sporozoites in the mosquito, consistent with a role in host tissue targeting and invasion. Gene disruption of pcrmp1 and 2 in the rodent malaria model, P. berghei, demonstrated that both are essential for transmission of the parasite from the mosquito to the mouse and has established their discrete and important roles in sporozoite targeting to the mosquito salivary gland. The unprecedented expression pattern and structural features of the PCRMPs thus suggest a variety of roles mediating host-parasite interactions throughout the parasite life cycle.

SAVANT: Solar Array Verification and Analysis Tool Demonstrated

NASA Technical Reports Server (NTRS)

Chock, Ricaurte

2000-01-01

The photovoltaics (PV) industry is now being held to strict specifications, such as end-oflife power requirements, that force them to overengineer their products to avoid contractual penalties. Such overengineering has been the only reliable way to meet such specifications. Unfortunately, it also results in a more costly process than is probably necessary. In our conversations with the PV industry, the issue of cost has been raised again and again. Consequently, the Photovoltaics and Space Environment Effects branch at the NASA Glenn Research Center at Lewis Field has been developing a software tool to address this problem. SAVANT, Glenn's tool for solar array verification and analysis is in the technology demonstration phase. Ongoing work has proven that more efficient and less costly PV designs should be possible by using SAVANT to predict the on-orbit life-cycle performance. The ultimate goal of the SAVANT project is to provide a user-friendly computer tool to predict PV on-orbit life-cycle performance. This should greatly simplify the tasks of scaling and designing the PV power component of any given flight or mission. By being able to predict how a particular PV article will perform, designers will be able to balance mission power requirements (both beginning-of-life and end-of-life) with survivability concerns such as power degradation due to radiation and/or contamination. Recent comparisons with actual flight data from the Photovoltaic Array Space Power Plus Diagnostics (PASP Plus) mission validate this approach.

Methodology for Software Reliability Prediction. Volume 1.

DTIC Science & Technology

1987-11-01

SPACECRAFT 0 MANNED SPACECRAFT B ATCH SYSTEM AIRBORNE AVIONICS 0 UNMANNED EVENT C014TROL a REAL TIME CLOSED 0 UNMANNED SPACECRAFT LOOP OPERATINS SPACECRAFT...software reliability. A Software Reliability Measurement Framework was established which spans the life cycle of a software system and includes the...specification, prediction, estimation, and assessment of software reliability. Data from 59 systems , representing over 5 million lines of code, were

Life cycle of soil sggregates: from root residue to microbial and physical hotspots

NASA Astrophysics Data System (ADS)

Ghezzehei, T. A.; Or, D.

2017-12-01

Soil aggregation is a physical state of soil in which clumps of primary soil particles are held together by biological and/or chemical cementing agents. Aggregations plays important role in storage and movement of water and essential gases, nutrient cycling, and ultimately supporting microbial and plant life. It is also one of the most dynamic and sensitive soil qualities, which readily responds to disturbances such as cultivation, fire, drought, flooding, and changes in vegetation. Soil aggregation that is primarily controlled by organic matter generally exhibits hierarchical organization of soil constituents into stable units that range in size from a few microns to centimeters. However, this conceptual model of soil aggregation as the key unifying mechanism remains poorly quantified and is rarely included in predictive soil models. Here we provide a biophysical framework for quantitative and predictive modeling of soil aggregation and its attendant soil characteristics. The framework treats aggregates as hotspots of biological, chemical and physical processes centered around roots and root residue. We keep track of the life cycle of an individual aggregate from it genesis in the rhizosphere, fueled by rhizodeposition and mediated by vigorous microbial activity, until its disappearance when the root-derived resources are depleted. The framework synthesizes current understanding of microbial life in porous media; water holding and soil binding capacity of biopolymers; and environmental controls on soil organic matter dynamics. The framework paves a way for integration of processes that are presently modeled as disparate or poorly coupled processes, including storage and protection of carbon, microbial activity, greenhouse gas fluxes, movement and storage of water, resistance of soils against erosion.

The construction of life prediction models for the design of Stirling engine heater components

NASA Technical Reports Server (NTRS)

Petrovich, A.; Bright, A.; Cronin, M.; Arnold, S.

1983-01-01

The service life of Stirling-engine heater structures of Fe-based high-temperature alloys is predicted using a numerical model based on a linear-damage approach and published test data (engine test data for a Co-based alloy and tensile-test results for both the Co-based and the Fe-based alloys). The operating principle of the automotive Stirling engine is reviewed; the economic and technical factors affecting the choice of heater material are surveyed; the test results are summarized in tables and graphs; the engine environment and automotive duty cycle are characterized; and the modeling procedure is explained. It is found that the statistical scatter of the fatigue properties of the heater components needs to be reduced (by decreasing the porosity of the cast material or employing wrought material in fatigue-prone locations) before the accuracy of life predictions can be improved.

Life prediction of materials exposed to monotonic and cyclic loading: Bibliography

NASA Technical Reports Server (NTRS)

Carpenter, J. L., Jr.; Moya, N.; Stuhrke, W. F.

1975-01-01

This bibliography is comprised of approximately 1200 reference citations related to the mechanics of failure in aerospace structures. Most of the references are for information on life prediction for materials exposed to monotonic and cyclic loading in elevated temperature environments such as that in the hot end of a gas turbine engine. Additional citations listed are for documents on the thermal and mechanical effects on solar cells in the cryogenic vacuum environment; radiation effects on high temperature mechanical properties; and high cycle fatigue technology as applicable to gas turbine engine bearings. The bibliography represents a search of the literature published in the period April 1962 through April 1974 and is largely limited to documents published in the United States. It is a companion volume to NASA CR-134750, Life Prediction of Materials Exposed to Monotonic and cyclic Loading - A Technology Survey.

NASALIFE - Component Fatigue and Creep Life Prediction Program

NASA Technical Reports Server (NTRS)

Gyekenyesi, John Z.; Murthy, Pappu L. N.; Mital, Subodh K.

2014-01-01

NASALIFE is a life prediction program for propulsion system components made of ceramic matrix composites (CMC) under cyclic thermo-mechanical loading and creep rupture conditions. Although the primary focus was for CMC components, the underlying methodologies are equally applicable to other material systems as well. The program references empirical data for low cycle fatigue (LCF), creep rupture, and static material properties as part of the life prediction process. Multiaxial stresses are accommodated by Von Mises based methods and a Walker model is used to address mean stress effects. Varying loads are reduced by the Rainflow counting method or a peak counting type method. Lastly, damage due to cyclic loading and creep is combined with Minor's Rule to determine damage due to cyclic loading, damage due to creep, and the total damage per mission and the number of potential missions the component can provide before failure.

Synergistic Effects of Frequency and Temperature on Damage Evolution and Life Prediction of Cross-Ply Ceramic Matrix Composites under Tension-Tension Fatigue Loading

NASA Astrophysics Data System (ADS)

Longbiao, Li

2017-10-01

In this paper, the synergistic effects of loading frequency and testing temperature on the fatigue damage evolution and life prediction of cross-ply SiC/MAS ceramic-matrix composite have been investigated. The damage parameters of the fatigue hysteresis modulus, fatigue hysteresis dissipated energy and the interface shear stress were used to monitor the damage evolution inside of SiC/MAS composite. The evolution of fatigue hysteresis dissipated energy, the interface shear stress and broken fibers fraction versus cycle number, and the fatigue life S-N curves of SiC/MAS composite under the loading frequency of 1 and 10 Hz at 566 °C and 1093 °C in air condition have been predicted. The synergistic effects of the loading frequency and testing temperature on the degradation rate of fatigue hysteresis dissipated energy and the interface shear stress have been analyzed.

Improved High-Cycle Fatigue (HCF) Life Prediction

DTIC Science & Technology

2001-01-01

fatigue in 2024 - T351 aluminum alloy ’, Wear 221, 24-36. Appendix 6C CHARACTERIZATION OF FRETTING FATIGUE INITIATED CRACKS P.J. Golden A.F...0.8. To evaluate the effects of surface residual stresses on notch fatigue life , shot peened specimens were tested at R = -1.0 and 0.1. Data in...Behavior - Response • The undamaged fatigue test program demonstrates the sensitivity of surface effects (for different

Microbially mediated transformations of phosphorus in the sea: new views of an old cycle.

PubMed

Karl, David M

2014-01-01

Phosphorus (P) is a required element for life. Its various chemical forms are found throughout the lithosphere and hydrosphere, where they are acted on by numerous abiotic and biotic processes collectively referred to as the P cycle. In the sea, microorganisms are primarily responsible for P assimilation and remineralization, including recently discovered P reduction-oxidation bioenergetic processes that add new complexity to the marine microbial P cycle. Human-induced enhancement of the global P cycle via mining of phosphate-bearing rock will likely influence the pace of P-cycle dynamics, especially in coastal marine habitats. The inextricable link between the P cycle and cycles of other bioelements predicts future impacts on, for example, nitrogen fixation and carbon dioxide sequestration. Additional laboratory and field research is required to build a comprehensive understanding of the marine microbial P cycle.

Can a quality-of-life assessment assist in identifying women at risk of prematurely discontinuing IVF treatment? A prospective cohort study utilizing the FertiQoL questionnaire.

PubMed

Neumann, Kay; Kayser, Janna; Depenbusch, Marion; Schultze-Mosgau, Askan; Griesinger, Georg

2018-07-01

This study aimed at assessing quality of life (QoL) by means of a validated measurement tool (FertiQoL) in German infertile patients before a first IVF/ICSI cycle with ancillary assessment of changes in FertiQoL scores after a failed first cycle and the predictive capacity of FertiQoL scores for treatment discontinuation. The validated FertiQoL tool consisting of 24 questions regarding fertility-specific aspects of QoL was used for this prospective cohort study conducted at a university affiliated IVF center in Germany. Female patients (n = 119) filled out the FertiQoL form and questionnaire on sociodemographic variables on initiation of a first- and second-cycle IVF/ICSI treatment, respectively. On initiation of a first IVF/ICSI cycle, the mean scores (± standard deviation) for subscales emotional, mind-body, relational, and social items were 62 (± 19), 75 (± 17), 82 (± 13), and 78 (± 14), respectively; the total FertiQoL score was 73 (± 12). The mean total FertiQoL score at initiation of a first treatment cycle did not differ between patients who continued vs. discontinued treatment in case of no pregnancy achievement in the first cycle (73) (± 10) vs. 74 (± 14), p = 0.46). Furthermore, the mean total FertiQoL score did not change after an unsuccessful first IVF cycle (74 vs. 76, p = 0.46). There was no statistical difference in a small sample size for FertiQoL scores between all groups. In this study, FertiQoL scores were, therefore, not usable to predict withdrawal from infertility treatment.

Prediction of the Creep-Fatigue Lifetime of Alloy 617: An Application of Non-destructive Evaluation and Information Integration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vivek Agarwal; Richard Wright; Timothy Roney

A relatively simple method using the nominal constant average stress information and the creep rupture model is developed to predict the creep-fatigue lifetime of Alloy 617, in terms of time to rupture. The nominal constant average stress is computed using the stress relaxation curve. The predicted time to rupture can be converted to number of cycles to failure using the strain range, the strain rate during each cycle, and the hold time information. The predicted creep-fatigue lifetime is validated against the experimental measurements of the creep-fatigue lifetime collected using conventional laboratory creep-fatigue tests. High temperature creep-fatigue tests of Alloy 617more » were conducted in air at 950°C with a tensile hold period of up to 1800s in a cycle at total strain ranges of 0.3% and 0.6%. It was observed that the proposed method is conservative in that the predicted lifetime is less than the experimentally determined values. The approach would be relevant to calculate the remaining useful life to a component like a steam generator that might fail by the creep-fatigue mechanism.« less

Green pastures: Do US real estate prices respond to population health?

PubMed

Nau, Claudia; Bishai, David

2018-01-01

We investigate whether communities with improving population health will subsequently experience rising real estate prices. Home price indices (HPIs) for 371 MSAs from 1990 to 2010 are regressed against life-expectancy five years prior. HPIs come from the Federal Housing Finance Agency. Life expectancy estimates come from the Institute of Health Metrics. Our analysis uses random and fixed effect models with a comprehensive set of controls. Life expectancy predicted increases in the HPI controlling for potential confounders. We found that, this effect varied spatially. Communities that invest their revenue from property taxes in public health infrastructure could benefit from a virtuous cycle of better health leading to higher property values. Communities that do not invest in health could enter vicious cycles and this could widen geospatial health and wealth disparities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Environmental Variability and Fluctuation of Coccidioidomycosis (Valley Fever) In California: Based on a New Framework Involving Fungal Life Cycle

NASA Astrophysics Data System (ADS)

Jia, S.; Okin, G. S.; Shafir, S. C.

2013-12-01

Coccidioidomycosis (valley fever), caused by inhalation of spores from pathogenic fungus includingCoccidiodes immitis (C. immitis) and Coccidioides posadasii (C. posadasii), is a disease endemic to arid regions in the southwest US, as well as parts of Central and South America. With a projected increase of drought in this region, an improved understanding of environmental factors behind the outbreaks of coccidioidomycosis will enable the prediction of coccidioidomycosis in a changing climate regime. Previous research shows the infections correlate with climate conditions including precipitation, temperature, and dust. However, most studies focus only on the environmental conditions of fungus growth, which is the first stage in the fungal life cycle. In contrast, we extend the analysis to the following two stages in the life cycle, arthrospore formation and dispersal, to form a better model to predict the disease outbreaks. Besides climate conditions, we use relative spectral mixture analysis (RSMA) based on MODIS MOD43 nadir BRDF adjusted reflectance (NBAR) data to derive the relative dynamics of green vegetation, non-photosynthetic vegetation and bare soil coverage as better indicators of soil moisture, which is important for arthospore formation and dispersal. After detecting the hotspots of disease outbreaks, we correlate seasonal incidence from 2000 to 2010 with the environmental variables zero to eight seasons before to obtain candidates for stepwise regression. Regression result shows a seasonal difference in the leading explanatory variables. Such difference indicates the different seasonal main influential process from fungal life cycle. C. immitis (fungus responsible for coccidioidomycosis outbreaks in California) growth explains outbreaks in winter and fall better than other two stages in the life cycle, while arthospore formation is more responsible for spring and summer outbreaks. As the driest season, summer has the largest area related with arthospore dispersal. The seasonal difference of main influential process relates to the length of lags between the outbreaks and stages in fungal life cycle. During wet seasons of California including winter and fall, outbreaks are less correlated with the short-lag process such as dispersal of arthospores because of high soil moisture. In contrast, the long-lag process like C.immitis growth is influential on outbreaks in wet seasons. The arthospore formation, especially during the latest dry season (with a lag less than one year), is more responsible for outbreaks in spring and summer, when the influence of C. immitis growth is dampened by time. However, arthospores formed and preserved years ago may introduce uncertainty to the seasonal lag patterns. The long lags also exist in outbreaks related to arthospore formation. By including all three stages of fungal life cycle, we formed a more comprehensive framework in explaining the relationship between environmental conditions and disease outbreaks. Such analysis can be extended to a finer temporal resolution (e.g. per month) to obtain a clearer picture between environmental variability and coccidioidomycosis fluctuation.

Life prediction of l6 steel using strain-life curve and cyclic stress-strain curve by means of low cycle fatigue testing

NASA Astrophysics Data System (ADS)

Inamdar, Sanket; Ukhande, Manoj; Date, Prashant; Lomate, Dattaprasad; Takale, Shyam; Singh, RKP

2017-05-01

L6 Steel is used as die material in closed die hot forging process. This material is having some unique properties. These properties are due to its composition. Strain softening is the noticeable property of this material. Due to this in spite of cracking at high stress this material gets plastically deformed and encounters loss in time as well as money. Studies of these properties are necessary to nurture this material at fullest extent. In this paper, numerous experiments have been carried on L6 material to evaluate cyclic Stress - strain behavior as swell as strain-life behavior of the material. Low cycle fatigue test is carried out on MTS fatigue test machine at fully reverse loading condition R=-1. Also strain softening effect on forging metal forming process is explained in detail. The failed samples during low cycle fatigue test further investigated metallurgically on scanning electron microscopy. Based on this study, life estimation of hot forging die is carried out and it’s correlation with actual shop floor data is found out. This work also concludes about effect of pre-treatments like nitro-carburizing and surface coating on L6 steel material, to enhance its fatigue life to certain extent.

Predicting Defects Using Information Intelligence Process Models in the Software Technology Project

PubMed Central

Selvaraj, Manjula Gandhi; Jayabal, Devi Shree; Srinivasan, Thenmozhi; Balasubramanie, Palanisamy

2015-01-01

A key differentiator in a competitive market place is customer satisfaction. As per Gartner 2012 report, only 75%–80% of IT projects are successful. Customer satisfaction should be considered as a part of business strategy. The associated project parameters should be proactively managed and the project outcome needs to be predicted by a technical manager. There is lot of focus on the end state and on minimizing defect leakage as much as possible. Focus should be on proactively managing and shifting left in the software life cycle engineering model. Identify the problem upfront in the project cycle and do not wait for lessons to be learnt and take reactive steps. This paper gives the practical applicability of using predictive models and illustrates use of these models in a project to predict system testing defects thus helping to reduce residual defects. PMID:26495427

Predicting Defects Using Information Intelligence Process Models in the Software Technology Project.

PubMed

Selvaraj, Manjula Gandhi; Jayabal, Devi Shree; Srinivasan, Thenmozhi; Balasubramanie, Palanisamy

2015-01-01

A key differentiator in a competitive market place is customer satisfaction. As per Gartner 2012 report, only 75%-80% of IT projects are successful. Customer satisfaction should be considered as a part of business strategy. The associated project parameters should be proactively managed and the project outcome needs to be predicted by a technical manager. There is lot of focus on the end state and on minimizing defect leakage as much as possible. Focus should be on proactively managing and shifting left in the software life cycle engineering model. Identify the problem upfront in the project cycle and do not wait for lessons to be learnt and take reactive steps. This paper gives the practical applicability of using predictive models and illustrates use of these models in a project to predict system testing defects thus helping to reduce residual defects.

Isothermal Fatigue, Damage Accumulation, and Life Prediction of a Woven PMC

NASA Technical Reports Server (NTRS)

Gyekenyesi, Andrew L.

1998-01-01

This dissertation focuses on the characterization of the fully reversed fatigue behavior exhibited by a carbon fiber/polyimide resin, woven laminate at room and elevated temperatures. Nondestructive video edge view microscopy and destructive sectioning techniques were used to study the microscopic damage mechanisms that evolved. The residual elastic stiffness was monitored and recorded throughout the fatigue life of the coupon. In addition, residual compressive strength tests were conducted on fatigue coupons with various degrees of damage as quantified by stiffness reduction. Experimental results indicated that the monotonic tensile properties were only minimally influenced by temperature, while the monotonic compressive and fully reversed fatigue properties displayed noticeable reductions due to the elevated temperature. The stiffness degradation, as a function of cycles, consisted of three stages; a short-lived high degradation period, a constant degradation rate segment composing the majority of the life, and a final stage demonstrating an increasing rate of degradation up to failure. Concerning the residual compressive strength tests at room and elevated temperatures, the elevated temperature coupons appeared much more sensitive to damage. At elevated temperatures, coupons experienced a much larger loss in compressive strength when compared to room temperature coupons with equivalent damage. The fatigue damage accumulation law proposed for the model incorporates a scalar representation for damage, but admits a multiaxial, anisotropic evolutionary law. The model predicts the current damage (as quantified by residual stiffness) and remnant life of a composite that has undergone a known load at temperature. The damage/life model is dependent on the applied multiaxial stress state as well as temperature. Comparisons between the model and data showed good predictive capabilities concerning stiffness degradation and cycles to failure.

Design and fabrication of the Mini-Brayton Recuperator (MBR)

NASA Technical Reports Server (NTRS)

Killackey, J. J.; Graves, R.; Mosinskis, G.

1978-01-01

Development of a recuperator for a 2.0 kW closed Brayton space power system is described. The plate-fin heat exchanger is fabricated entirely from Hastelloy X and is designed for 10 years continuous operation at 1000 K (1300 F) with a Xenon-helium working fluid. Special design provisions assure uniform flow distribution, crucial for meeting 0.975 temperature effectiveness. Low-cycle fatigue, resulting from repeated startup and shutdown cycles, was identified as the most critical structural design problem. It is predicted that the unit has a minimum fatigue life of 220 cycles. This is in excess of the BIPS requirement of 100 cycles. Heat transfer performance and thermal cycle testing with air, using a prototype unit, verified that all design objectives can be met.

Summary of the Sixth Persh Workshop: Corrosion Policy Guiding Science and Technology

DTIC Science & Technology

2016-01-01

mitigating corrosion. Corrosion affects military readiness, so corrosion prevention and control (CPC) have a high priority for the DOD since CPC is a...resulting in high -cost repairs. Corrosion mitigation is thus a key cost-effective approach for system maintainability and reduced life cycle costs. The... treatments . • Develop corrosion databases and corrosion models for predictive evaluation. Testing methods for realistic prediction of performance

Do-or-die life cycles and diverse post-infection resistance mechanisms limit the evolution of parasite host ranges.

PubMed

Sieber, Michael; Gudelj, Ivana

2014-04-01

In light of the dynamic nature of parasite host ranges and documented potential for rapid host shifts, the observed high host specificity of most parasites remains an ecological paradox. Different variants of host-use trade-offs have become a mainstay of theoretical explanations of the prevalence of host specialism, but empirical evidence for such trade-offs is rare. We propose an alternative theory based on basic features of the parasite life cycle: host selection and subsequent intrahost replication. We introduce a new concept of effective burst size that accounts for the fact that successful host selection does not guarantee intrahost replication. Our theory makes a general prediction that a parasite will expand its host range if its effective burst size is positive. An in silico model of bacteria-phage coevolution verifies our predictions and demonstrates that the tendency for relatively narrow host ranges in parasites can be explained even in the absence of trade-offs. © 2014 John Wiley & Sons Ltd/CNRS.

Life cycle assessment needs predictive spatial modelling for biodiversity and ecosystem services

PubMed Central

Chaplin-Kramer, Rebecca; Sim, Sarah; Hamel, Perrine; Bryant, Benjamin; Noe, Ryan; Mueller, Carina; Rigarlsford, Giles; Kulak, Michal; Kowal, Virginia; Sharp, Richard; Clavreul, Julie; Price, Edward; Polasky, Stephen; Ruckelshaus, Mary; Daily, Gretchen

2017-01-01

International corporations in an increasingly globalized economy exert a major influence on the planet's land use and resources through their product design and material sourcing decisions. Many companies use life cycle assessment (LCA) to evaluate their sustainability, yet commonly-used LCA methodologies lack the spatial resolution and predictive ecological information to reveal key impacts on climate, water and biodiversity. We present advances for LCA that integrate spatially explicit modelling of land change and ecosystem services in a Land-Use Change Improved (LUCI)-LCA. Comparing increased demand for bioplastics derived from two alternative feedstock-location scenarios for maize and sugarcane, we find that the LUCI-LCA approach yields results opposite to those of standard LCA for greenhouse gas emissions and water consumption, and of different magnitudes for soil erosion and biodiversity. This approach highlights the importance of including information about where and how land-use change and related impacts will occur in supply chain and innovation decisions. PMID:28429710

Analysis of thermomechanical fatigue of unidirectional titanium metal matrix composites

NASA Technical Reports Server (NTRS)

Mirdamadi, M.; Johnson, W. S.; Bahei-El-din, Y. A.; Castelli, M. G.

1991-01-01

Thermomechanical fatigue (TMF) data was generated for a Ti-15V-3Cr-3Al-3Sn (Ti-15-3) material reinforced with SCS-6 silicon carbide fibers for both in-phase and out-of-phase thermomechanical cycling. Significant differences in failure mechanisms and fatigue life were noted for in-phase and out-of-phase testing. The purpose of the research is to apply a micromechanical model to the analysis of the data. The analysis predicts the stresses in the fiber and the matrix during the thermal and mechanical cycling by calculating both the thermal and mechanical stresses and their rate-dependent behavior. The rate-dependent behavior of the matrix was characterized and was used to calculate the constituent stresses in the composite. The predicted 0 degree fiber stress range was used to explain the composite failure. It was found that for a given condition, temperature, loading frequency, and time at temperature, the 0 degree fiber stress range may control the fatigue life of the unidirectional composite.

Life cycle assessment needs predictive spatial modelling for biodiversity and ecosystem services

NASA Astrophysics Data System (ADS)

Chaplin-Kramer, Rebecca; Sim, Sarah; Hamel, Perrine; Bryant, Benjamin; Noe, Ryan; Mueller, Carina; Rigarlsford, Giles; Kulak, Michal; Kowal, Virginia; Sharp, Richard; Clavreul, Julie; Price, Edward; Polasky, Stephen; Ruckelshaus, Mary; Daily, Gretchen

2017-04-01

International corporations in an increasingly globalized economy exert a major influence on the planet's land use and resources through their product design and material sourcing decisions. Many companies use life cycle assessment (LCA) to evaluate their sustainability, yet commonly-used LCA methodologies lack the spatial resolution and predictive ecological information to reveal key impacts on climate, water and biodiversity. We present advances for LCA that integrate spatially explicit modelling of land change and ecosystem services in a Land-Use Change Improved (LUCI)-LCA. Comparing increased demand for bioplastics derived from two alternative feedstock-location scenarios for maize and sugarcane, we find that the LUCI-LCA approach yields results opposite to those of standard LCA for greenhouse gas emissions and water consumption, and of different magnitudes for soil erosion and biodiversity. This approach highlights the importance of including information about where and how land-use change and related impacts will occur in supply chain and innovation decisions.

Low-cycle fatigue analysis of a cooled copper combustion chamber

NASA Technical Reports Server (NTRS)

Miller, R. W.

1974-01-01

A three-dimensional finite element elastoplastic strain analysis was performed for the throat section of regeneratively cooled rocket engine combustion chamber. The analysis included thermal and pressure loads, and the effects of temperature dependent material properties, to determine the strain range corresponding to the engine operating cycle. The strain range was used in conjunction with OFHC copper isothermal fatigue test data to predict engine low-cycle fatigue life. The analysis was performed for chamber configuration and operating conditions corresponding to a hydrogen-oxygen chamber which was fatigue tested to failure at the NASA Lewis Research Center.

Lithium-Ion Batteries for Aerospace Applications

NASA Technical Reports Server (NTRS)

Surampudi, S.; Halpert, G.; Marsh, R. A.; James, R.

1999-01-01

This presentation reviews: (1) the goals and objectives, (2) the NASA and Airforce requirements, (3) the potential near term missions, (4) management approach, (5) the technical approach and (6) the program road map. The objectives of the program include: (1) develop high specific energy and long life lithium ion cells and smart batteries for aerospace and defense applications, (2) establish domestic production sources, and to demonstrate technological readiness for various missions. The management approach is to encourage the teaming of universities, R&D organizations, and battery manufacturing companies, to build on existing commercial and government technology, and to develop two sources for manufacturing cells and batteries. The technological approach includes: (1) develop advanced electrode materials and electrolytes to achieve improved low temperature performance and long cycle life, (2) optimize cell design to improve specific energy, cycle life and safety, (3) establish manufacturing processes to ensure predictable performance, (4) establish manufacturing processes to ensure predictable performance, (5) develop aerospace lithium ion cells in various AH sizes and voltages, (6) develop electronics for smart battery management, (7) develop a performance database required for various applications, and (8) demonstrate technology readiness for the various missions. Charts which review the requirements for the Li-ion battery development program are presented.

Bridging the gap between life cycle inventory and impact assessment for toxicological assessments of pesticides used in crop production.

PubMed

van Zelm, Rosalie; Larrey-Lassalle, Pyrène; Roux, Philippe

2014-04-01

In Life Cycle Assessment (LCA), the Life Cycle Inventory (LCI) provides emission data to the various environmental compartments and Life Cycle Impact Assessment (LCIA) determines the final distribution, fate and effects. Due to the overlap between the Technosphere (anthropogenic system) and Ecosphere (environment) in agricultural case studies, it is, however, complicated to establish what LCI needs to capture and where LCIA takes over. This paper aims to provide guidance and improvements of LCI/LCIA boundary definitions, in the dimensions of space and time. For this, a literature review was conducted to provide a clear overview of available methods and models for both LCI and LCIA regarding toxicological assessments of pesticides used in crop production. Guidelines are provided to overcome the gaps between LCI and LCIA modeling, and prevent the overlaps in their respective operational spheres. The proposed framework provides a starting point for LCA practitioners to gather the right data and use the proper models to include all relevant emission and exposure routes where possible. It is also able to predict a clear distinction between efficient and inefficient management practices (e.g. using different application rates, washing and rinsing management, etc.). By applying this framework for toxicological assessments of pesticides, LCI and LCIA can be directly linked, removing any overlaps or gaps in between the two distinct LCA steps. Copyright © 2013 Elsevier Ltd. All rights reserved.

[Life cycle strategies: a synthesis of empirical and theoretical approaches].

PubMed

Romanovskiĭ, Iu E

1998-01-01

A scheme of relationships among life-history characters is developed on assumptions of determinate growth and dependence of juvenile mortality on the specific growth rate. It is shown that constraints on the relative neonate size, (W0/W infinity), and minimum value of the biotic potential, (rmax), lead to "triangular" shape of life history set on the plain defined by juvenile and adult mortality. This completely coincides with the Ramenskiĭ++--Grime (C-S-R) classification of life-history strategies. Phylogenetic constraints can reduce this set to a relatively narŕow r/K-continuum specifically oriented for a certain taxon. Similar restrictions generate models of life history optimization which predict interspecific allometries between life-history traits.

A fitness trade-off between seasons causes multigenerational cycles in phenotype and population size

PubMed Central

Betini, Gustavo S; McAdam, Andrew G; Griswold, Cortland K; Norris, D Ryan

2017-01-01

Although seasonality is widespread and can cause fluctuations in the intensity and direction of natural selection, we have little information about the consequences of seasonal fitness trade-offs for population dynamics. Here we exposed populations of Drosophila melanogaster to repeated seasonal changes in resources across 58 generations and used experimental and mathematical approaches to investigate how viability selection on body size in the non-breeding season could affect demography. We show that opposing seasonal episodes of natural selection on body size interacted with both direct and delayed density dependence to cause populations to undergo predictable multigenerational density cycles. Our results provide evidence that seasonality can set the conditions for life-history trade-offs and density dependence, which can, in turn, interact to cause multigenerational population cycles. DOI: http://dx.doi.org/10.7554/eLife.18770.001 PMID:28164780

The impact of hospital accreditation on clinical documentation compliance: a life cycle explanation using interrupted time series analysis

PubMed Central

Devkaran, Subashnie; O'Farrell, Patrick N

2014-01-01

Objective To evaluate whether accredited hospitals maintain quality and patient safety standards over the accreditation cycle by testing a life cycle explanation of accreditation on quality measures. Four distinct phases of the accreditation life cycle were defined based on the Joint Commission International process. Predictions concerning the time series trend of compliance during each phase were specified and tested. Design Interrupted time series (ITS) regression analysis of 23 quality and accreditation compliance measures. Setting A 150-bed multispecialty hospital in Abu Dhabi, UAE. Participants Each month (over 48 months) a simple random sample of 24% of patient records was audited, resulting in 276 000 observations collected from 12 000 patient records, drawn from a population of 50 000. Intervention(s) The impact of hospital accreditation on the 23 quality measures was observed for 48 months, 1 year preaccreditation (2009) and 3-year postaccreditation (2010–2012). Main outcome measure(s) The Life Cycle Model was evaluated by aggregating the data for 23 quality measures to produce a composite score (YC) and fitting an ITS regression equation to the unweighted monthly mean of the series. Results The four phases of the life cycle are as follows: the initiation phase, the presurvey phase, the postaccreditation slump phase and the stagnation phase. The Life Cycle Model explains 87% of the variation in quality compliance measures (R2=0.87). The ITS model not only contains three significant variables (β1, β2 and β3) (p≤0.001), but also the size of the coefficients indicates that the effects of these variables are substantial (β1=2.19, β2=−3.95 (95% CI −6.39 to −1.51) and β3=−2.16 (95% CI −2.52 to −1.80). Conclusions Although there was a reduction in compliance immediately after the accreditation survey, the lack of subsequent fading in quality performance should be a reassurance to researchers, managers, clinicians and accreditors. PMID:25095876

The impact of hospital accreditation on clinical documentation compliance: a life cycle explanation using interrupted time series analysis.

PubMed

Devkaran, Subashnie; O'Farrell, Patrick N

2014-08-05

To evaluate whether accredited hospitals maintain quality and patient safety standards over the accreditation cycle by testing a life cycle explanation of accreditation on quality measures. Four distinct phases of the accreditation life cycle were defined based on the Joint Commission International process. Predictions concerning the time series trend of compliance during each phase were specified and tested. Interrupted time series (ITS) regression analysis of 23 quality and accreditation compliance measures. A 150-bed multispecialty hospital in Abu Dhabi, UAE. Each month (over 48 months) a simple random sample of 24% of patient records was audited, resulting in 276,000 observations collected from 12,000 patient records, drawn from a population of 50,000. The impact of hospital accreditation on the 23 quality measures was observed for 48 months, 1 year preaccreditation (2009) and 3-year postaccreditation (2010-2012). The Life Cycle Model was evaluated by aggregating the data for 23 quality measures to produce a composite score (YC) and fitting an ITS regression equation to the unweighted monthly mean of the series. The four phases of the life cycle are as follows: the initiation phase, the presurvey phase, the postaccreditation slump phase and the stagnation phase. The Life Cycle Model explains 87% of the variation in quality compliance measures (R(2)=0.87). The ITS model not only contains three significant variables (β1, β2 and β3) (p≤0.001), but also the size of the coefficients indicates that the effects of these variables are substantial (β1=2.19, β2=-3.95 (95% CI -6.39 to -1.51) and β3=-2.16 (95% CI -2.52 to -1.80). Although there was a reduction in compliance immediately after the accreditation survey, the lack of subsequent fading in quality performance should be a reassurance to researchers, managers, clinicians and accreditors. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Towards a Delamination Fatigue Methodology for Composite Materials

NASA Technical Reports Server (NTRS)

OBrien, Thomas K.

2007-01-01

A methodology that accounts for both delaminaton onset and growth in composite structural components is proposed for improved fatigue life prediction to reduce life cycle costs and improve accept/reject criteria for manufacturing flaws. The benefits of using a Delamination Onset Threshold (DOT) approach in combination with a Modified Damage Tolerance (MDT) approach is highlighted. The use of this combined approach to establish accept/reject criteria, requiring less conservative initial manufacturing flaw sizes, is illustrated.

WaterNet:The NASA Water Cycle Solutions Network

NASA Astrophysics Data System (ADS)

Belvedere, D. R.; Houser, P. R.; Pozzi, W.; Imam, B.; Schiffer, R.; Schlosser, C. A.; Gupta, H.; Martinez, G.; Lopez, V.; Vorosmarty, C.; Fekete, B.; Matthews, D.; Lawford, R.; Welty, C.; Seck, A.

2008-12-01

Water is essential to life and directly impacts and constrains society's welfare, progress, and sustainable growth, and is continuously being transformed by climate change, erosion, pollution, and engineering. Projections of the effects of such factors will remain speculative until more effective global prediction systems and applications are implemented. NASA's unique role is to use its view from space to improve water and energy cycle monitoring and prediction, and has taken steps to collaborate and improve interoperability with existing networks and nodes of research organizations, operational agencies, science communities, and private industry. WaterNet is a Solutions Network, devoted to the identification and recommendation of candidate solutions that propose ways in which water-cycle related NASA research results can be skillfully applied by partner agencies, international organizations, state, and local governments. It is designed to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend NASA research results to augment Decision Support Tools that address national needs.

Prospective time-resolved LCA of fully electric supercap vehicles in Germany.

PubMed

Zimmermann, Benedikt M; Dura, Hanna; Baumann, Manuel J; Weil, Marcel R

2015-07-01

The ongoing transition of the German electricity supply toward a higher share of renewable and sustainable energy sources, called Energiewende in German, has led to dynamic changes in the environmental impact of electricity over the last few years. Prominent scenario studies predict that comparable dynamics will continue in the coming decades, which will further improve the environmental performance of Germany's electricity supply. Life cycle assessment (LCA) is the methodology commonly used to evaluate environmental performance. Previous LCA studies on electric vehicles have shown that the electricity supply for the vehicles' operation is responsible for the major part of their environmental impact. The core question of this study is how the prospective dynamic development of the German electricity mix will affect the impact of electric vehicles operated in Germany and how LCA can be adapted to analyze this impact in a more robust manner. The previously suggested approach of time-resolved LCA, which is located between static and dynamic LCA, is used in this study and compared with several static approaches. Furthermore, the uncertainty issue associated with scenario studies is addressed in general and in relation to time-resolved LCA. Two scenario studies relevant to policy making have been selected, but a moderate number of modifications have been necessary to adapt the data to the requirements of a life cycle inventory. A potential, fully electric vehicle powered by a supercapacitor energy storage system is used as a generic example. The results show that substantial improvements in the environmental repercussions of the electricity supply and, consequentially, of electric vehicles will be achieved between 2020 and 2031 on the basis of the energy mixes predicted in both studies. This study concludes that although scenarios might not be able to predict the future, they should nonetheless be used as data sources in prospective LCA studies, because in many cases historic data appears to be unsuitable for providing realistic information on the future. The time-resolved LCA approach improves the assessment's robustness substantially, especially when nonlinear developments are foreseen in the future scenarios. This allows for a reduction of bias in LCA-based decision making. However, a deeper integration of time-resolved data in the life cycle inventory and the implementation of a more suitable software framework are desirable. The study describes how life cycle assessment's (LCA) robustness can be improved by respecting prospective fluctuations, like the transition of the German electricity mix, in the modeling of the life cycle inventory. It presents a feasible and rather simple process to add time-resolved data to LCA. The study selects 2 different future scenarios from important German studies and processes their data systematically to make them compatible with the requirements of a life cycle inventory. The use of external scenarios as basis for future-oriented LCA is reflected critically. A case study on electric mobility is presented and used to compare historic, prospective static, and prospective time-resolved electricity mix modeling approaches. The case study emphasizes the benefits of time-resolved LCA in direct comparison with the currently used approaches. © 2015 SETAC.

Thermal Change and the Dynamics of Multi-Host Parasite Life Cycles in Aquatic Ecosystems.

PubMed

Barber, Iain; Berkhout, Boris W; Ismail, Zalina

2016-10-01

Altered thermal regimes associated with climate change are impacting significantly on the physical, chemical, and biological characteristics of the Earth's natural ecosystems, with important implications for the biology of aquatic organisms. As well as impacting the biology of individual species, changing thermal regimes have the capacity to mediate ecological interactions between species, and the potential for climate change to impact host-parasite interactions in aquatic ecosystems is now well recognized. Predicting what will happen to the prevalence and intensity of infection of parasites with multiple hosts in their life cycles is especially challenging because the addition of each additional host dramatically increases the potential permutations of response. In this short review, we provide an overview of the diverse routes by which altered thermal regimes can impact the dynamics of multi-host parasite life cycles in aquatic ecosystems. In addition, we examine how experimentally amenable host-parasite systems are being used to determine the consequences of changing environmental temperatures for these different types of mechanism. Our overarching aim is to examine the potential of changing thermal regimes to alter not only the biology of hosts and parasites, but also the biology of interactions between hosts and parasites. We also hope to illustrate the complexity that is likely to be involved in making predictions about the dynamics of infection by multi-host parasites in thermally challenged aquatic ecosystems. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.

Effect of Plastic Strain Range on Prediction of the Onset of Crack Growth for Low-Cycle Fatigue of SUS316NG Studied using Ultrasonic Back-Reflection

NASA Astrophysics Data System (ADS)

Nurul, Islam Md.; Arai, Yoshio; Araki, Wakako

Strain range controlled low-cycle fatigue tests were conducted using ultrasonic method in order to investigate the effect of plastic strain range on the remaining life of austenitic stainless steel SUS316NG before the onset of crack growth in its early stages of fatigue. It was found that the decrease in ultrasonic back-reflection intensity from the surface of the material, caused by the increase in average dislocation density with localized plastic deformation at persistent slip bands (PSBs), starts earlier with increase in the plastic strain range. The amount of decrease in ultrasonic back-reflection before the onset of crack growth increases for larger plastic strain range. The difference in the cumulative plastic strains at the onset of crack growth and at the onset of decrease in the ultrasonic back-reflection remained constant over the range of tested plastic strain. This result can be used to predict the remaining life before the onset of crack growth within the plastic strain range used in this study. In addition, we present and evaluate another method to predict damage evolution involving ultrasound attenuation caused by PSBs.

The Economics and Psychology of Personality Traits

ERIC Educational Resources Information Center

Borghans, Lex; Duckworth, Angela Lee; Heckman, James J.; ter Weel, Bas

2008-01-01

This paper explores the interface between personality psychology and economics. We examine the predictive power of personality and the stability of personality traits over the life cycle. We develop simple analytical frameworks for interpreting the evidence in personality psychology and suggest promising avenues for future research. The paper…

Complex Population Responses to Food Resources in the Marine Crustacean Americamysis Bahia

EPA Science Inventory

Most observations of stressor effects on marine crustaceans are made on individuals or even-aged cohorts. Results of these studies are difficult to translate into ecological predictions, either because life cycle models are incomplete, or because stressor effects on mixed age po...

Thermal barrier coating life prediction model development

NASA Technical Reports Server (NTRS)

Demasi, J. T.

1986-01-01

A methodology is established to predict thermal barrier coating life in a environment similar to that experienced by gas turbine airfoils. Experiments were conducted to determine failure modes of the thermal barrier coating. Analytical studies were employed to derive a life prediction model. A review of experimental and flight service components as well as laboratory post evaluations indicates that the predominant mode of TBC failure involves thermomechanical spallation of the ceramic coating layer. This ceramic spallation involves the formation of a dominant crack in the ceramic coating parallel to and closely adjacent to the topologically complex metal ceramic interface. This mechanical failure mode clearly is influenced by thermal exposure effects as shown in experiments conducted to study thermal pre-exposure and thermal cycle-rate effects. The preliminary life prediction model developed focuses on the two major damage modes identified in the critical experiments tasks. The first of these involves a mechanical driving force, resulting from cyclic strains and stresses caused by thermally induced and externally imposed mechanical loads. The second is an environmental driving force based on experimental results, and is believed to be related to bond coat oxidation. It is also believed that the growth of this oxide scale influences the intensity of the mechanical driving force.

Cardiomyocyte cell cycle control and growth estimation in vivo--an analysis based on cardiomyocyte nuclei.

PubMed

Walsh, Stuart; Pontén, Annica; Fleischmann, Bernd K; Jovinge, Stefan

2010-06-01

Adult mammalian cardiomyocytes are traditionally viewed as being permanently withdrawn from the cell cycle. Whereas some groups have reported none, others have reported extensive mitosis in adult myocardium under steady-state conditions. Recently, a highly specific assay of 14C dating in humans has suggested a continuous generation of cardiomyocytes in the adult, albeit at a very low rate. Mice represent the most commonly used animal model for these studies, but their short lifespan makes them unsuitable for 14C studies. Herein, we investigate the cellular growth pattern for murine cardiomyocyte growth under steady-state conditions, addressed with new analytical and technical strategies, and we furthermore relate this to gene expression patterns. The observed levels of DNA synthesis in early life were associated with cardiomyocyte proliferation. Mitosis was prolonged into early life, longer than the most conservative previous estimates. DNA synthesis in neonatal life was attributable to bi-nucleation, therefore suggesting that cardiomyocytes withdraw from the cell cycle shortly after birth. No cell cycle activity was observed in adult cardiomyocytes and significant polyploidy was observed in cardiomyocyte nuclei. Gene analyses identified 32 genes whose expression was predicted to be particular to day 3-4 neonatal myocytes, compared with embryonic or adult cells. These cell cycle-associated genes are crucial to the understanding of the mechanisms of bi-nucleation and physiological cellular growth in the neonatal period.

Each life stage matters: the importance of assessing the response to climate change over the complete life cycle in butterflies.

PubMed

Radchuk, Viktoriia; Turlure, Camille; Schtickzelle, Nicolas

2013-01-01

As ectothermic organisms, butterflies have widely been used as models to explore the predicted impacts of climate change. However, most studies explore only one life stage; to our best knowledge, none have integrated the impact of temperature on the vital rates of all life stages for a species of conservation concern. Besides, most population viability analysis models for butterflies are based on yearly population growth rate, precluding the implementation and assessment of important climate change scenarios, where climate change occurs mainly, or differently, during some seasons. Here, we used a combination of laboratory and field experiments to quantify the impact of temperature on all life stages of a vulnerable glacial relict butterfly. Next, we integrated these impacts into an overall population response using a deterministic periodic matrix model and explored the impact of several climate change scenarios. Temperature positively affected egg, pre-diapause larva and pupal survival, and the number of eggs laid by a female; only the survival of overwintering larva was negatively affected by an increase in temperature. Despite the positive impact of warming on many life stages, population viability was reduced under all scenarios, with predictions of much shorter times to extinction than under the baseline (current temperature situation) scenario. Indeed, model predictions were the most sensitive to changes in survival of overwintering larva, the only stage negatively affected by warming. A proper consideration of every stage of the life cycle is important when designing conservation guidelines in the light of climate change. This is in line with the resource-based habitat view, which explicitly refers to the habitat as a collection of resources needed for all life stages of the species. We, therefore, encourage adopting a resource-based habitat view for population viability analysis and development of conservation guidelines for butterflies, and more generally, other organisms. Life stages that are cryptic or difficult to study should not be forsaken as they may be key determinants in the overall response to climate change, as we found with overwintering Boloria eunomia larvae. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Structural analysis of cylindrical thrust chambers, volume 3

NASA Technical Reports Server (NTRS)

Pearson, M. L.

1981-01-01

A system of three computer programs is described for use in conjunction with the BOPAGE finite element program. The programs are demonstrated by analyzing cumulative plastic deformation in a regeneratively cooled rocket thrust chamber. The codes provide the capability to predict geometric and material nonlinear behavior of cyclically loaded structures without performing a cycle-by-cycle analysis over the life of the structure. The program set consists of a BOPACE restart tape reader routine, and extrapolation program and a plot package.

Structural analysis of cylindrical thrust chambers, volume 1

NASA Technical Reports Server (NTRS)

Armstrong, W. H.

1979-01-01

Life predictions of regeneratively cooled rocket thrust chambers are normally derived from classical material fatigue principles. The failures observed in experimental thrust chambers do not appear to be due entirely to material fatigue. The chamber coolant walls in the failed areas exhibit progressive bulging and thinning during cyclic firings until the wall stress finally exceeds the material rupture stress and failure occurs. A preliminary analysis of an oxygen free high conductivity (OFHC) copper cylindrical thrust chamber demonstrated that the inclusion of cumulative cyclic plastic effects enables the observed coolant wall thinout to be predicted. The thinout curve constructed from the referent analysis of 10 firing cycles was extrapolated from the tenth cycle to the 200th cycle. The preliminary OFHC copper chamber 10-cycle analysis was extended so that the extrapolated thinout curve could be established by performing cyclic analysis of deformed configurations at 100 and 200 cycles. Thus the original range of extrapolation was reduced and the thinout curve was adjusted by using calculated thinout rates at 100 and 100 cycles. An analysis of the same underformed chamber model constructed of half-hard Amzirc to study the effect of material properties on the thinout curve is included.

Limit cycles at the outer edge of the habitable zone

NASA Astrophysics Data System (ADS)

Haqq-Misra, J. D.; Kopparapu, R.; Batalha, N. E.; Harman, C.; Kasting, J. F.

2016-12-01

The liquid water habitable zone (HZ) describes the orbital distance at which a terrestrial planet can maintain above-freezing conditions through regulation by the carbonate-silicate cycle. Calculations with one-dimensional climate models predict that the inner edge of the HZ is limited by water loss through a runaway greenhouse, while the outer edge of the HZ is bounded by the maximum greenhouse effect of carbon dioxide. This classic picture of the HZ continues to guide interpretation of exoplanet discoveries; however, recent calculations have shown that terrestrial planets near the outer edge of the HZ may exhibit other behaviors that affect their habitability. Here I discuss results from a hierarchy of climate models to understand the stellar environments most likely to support a habitable planet. I present energy balance climate model calculations showing the conditions under which planets in the outer regions of the habitable zone should oscillate between long, globally glaciated states and shorter periods of climatic warmth, known as `limit cycles.' Such conditions would be inimical to the development of complex land life, including intelligent life. Limit cycles may also provide an explanation for fluvial features on early Mars, although this requires additional greenhouse warming by hydrogen. These calculations show that the net volcanic outgassing rate and the propensity for plant life to sequester carbon dioxide are critical factors that determine the susceptibility of a planet to limit cycling. I argue that planets orbiting mid G- to mid K-type stars offer more opportunity for supporting advanced life than do planets around F-type stars or M-type stars.

Probability of failure prediction for step-stress fatigue under sine or random stress

NASA Technical Reports Server (NTRS)

Lambert, R. G.

1979-01-01

A previously proposed cumulative fatigue damage law is extended to predict the probability of failure or fatigue life for structural materials with S-N fatigue curves represented as a scatterband of failure points. The proposed law applies to structures subjected to sinusoidal or random stresses and includes the effect of initial crack (i.e., flaw) sizes. The corrected cycle ratio damage function is shown to have physical significance.

Evolution and regulation of complex life cycles: a brown algal perspective.

PubMed

Cock, J Mark; Godfroy, Olivier; Macaisne, Nicolas; Peters, Akira F; Coelho, Susana M

2014-02-01

The life cycle of an organism is one of its fundamental features, influencing many aspects of its biology. The brown algae exhibit a diverse range of life cycles indicating that transitions between life cycle types may have been key adaptive events in the evolution of this group. Life cycle mutants, identified in the model organism Ectocarpus, are providing information about how life cycle progression is regulated at the molecular level in brown algae. We explore some of the implications of the phenotypes of the life cycle mutants described to date and draw comparisons with recent insights into life cycle regulation in the green lineage. Given the importance of coordinating growth and development with life cycle progression, we suggest that the co-option of ancient life cycle regulators to control key developmental events may be a common feature in diverse groups of multicellular eukaryotes. Copyright © 2013 Elsevier Ltd. All rights reserved.

Complex life cycles and offspring provisioning in marine invertebrates.

PubMed

Marshall, Dustin J; Keough, Michael J

2006-10-01

Offspring size can have pervasive effects throughout an organism's life history. Mothers can make either a few large or many small offspring, and the balance between these extremes is determined by the relationship between offspring size and performance. This relationship in turn is thought to be determined by the offspring's environment. Recently, it has become clear that events in one life-history stage can strongly affect performance in another. Given these strong carryover effects, we asked whether events in the larval phase can change the relationship between offspring size and performance in the adult phase. We manipulated the length of the larval period in the bryozoan Bugula neritina and then examined the relationship between offspring size and various parameters of adult performance under field conditions. We found that despite the adult stage being outplanted into identical conditions, different offspring sizes were predicted to be optimal, depending on the experience of those adults as larvae. This work highlights the fact that the strong phenotypic links between life-history stages may result in optimal offspring size being highly unpredictable for organisms with complex life cycles.

Calculation of thermomechanical fatigue life based on isothermal behavior

NASA Technical Reports Server (NTRS)

Halford, Gary R.; Saltsman, James F.

1987-01-01

The isothermal and thermomechanical fatigue (TMF) crack initiation response of a hypothetical material was analyzed. Expected thermomechanical behavior was evaluated numerically based on simple, isothermal, cyclic stress-strain - time characteristics and on strainrange versus cyclic life relations that have been assigned to the material. The attempt was made to establish basic minimum requirements for the development of a physically accurate TMF life-prediction model. A worthy method must be able to deal with the simplest of conditions: that is, those for which thermal cycling, per se, introduces no damage mechanisms other than those found in isothermal behavior. Under these assumed conditions, the TMF life should be obtained uniquely from known isothermal behavior. The ramifications of making more complex assumptions will be dealt with in future studies. Although analyses are only in their early stages, considerable insight has been gained in understanding the characteristics of several existing high-temperature life-prediction methods. The present work indicates that the most viable damage parameter is based on the inelastic strainrange.

Fate and transformation of graphene oxide in marine systems

EPA Science Inventory

Graphene oxide (GO) may be released into natural waters at different phases of its life cycle. Currently, there is no study on the fate of GO in seawater, which is predicted to be a major sink for many engineered nanomaterials. In this study, the influences of salinity (0-50 &per...

Effects of Coastal Acidification on the Life Cycle and Fitness of the Mysid Shrimp Americamysis Bahia

EPA Science Inventory

Most studies of animal responses to CO2-induced ocean acidification focus on isolated individuals or uniformly aged and conditioned cohorts that lack the complexities typical of wild populations. These studies have become the primary data source for meta-analytic predictions abo...

Traits of an invasive grass conferring an early growth advantage over native grasses

USDA-ARS?s Scientific Manuscript database

Plant invasions are a defining phenomenon of the Anthropocene. Plant traits that predict invasiveness could be unclear when the exotic species are of the same functional group as the dominants, because by definition they would have similar life cycles, morphologies, and physiologies. Exotic specie...

Population-level Experiments for Population-level Risk Assessment: An Example Using the Opposum Shrimp Americamysis bahia (NACSETAC)

EPA Science Inventory

Most observations of stressor effects on marine crustaceans are made on individuals or even-aged cohorts. Results of these studies are difficult to translate into ecological predictions, either because life cycle models are incomplete, or because stressor effects on mixed age po...

Inverse Demographic Analysis of Compensatory Responses to Resource Limitation in the Mysid Crustacean Americamysis bahia

EPA Science Inventory

Most observations of stressor effects on marine crustaceans are made on individuals or even-aged cohorts. Results of these studies are difficult to translate into ecological predictions, either because life cycle models are incomplete, or because stressor effects on mixed age po...

Crop development related to temperature and photoperiod

USDA-ARS?s Scientific Manuscript database

Plant development, or the progression of plants through their life cycle, has been of great interest in human history because of the need to know and predict when the harvested part of the plant was at the optimum stage. This knowledge was especially important (even vital) in medicinal plants, where...

Damage Tolerant Analysis of Cracked Al 2024-T3 Panels repaired with Single Boron/Epoxy Patch

NASA Astrophysics Data System (ADS)

Mahajan, Akshay D.; Murthy, A. Ramachandra; Nanda Kumar, M. R.; Gopinath, Smitha

2018-06-01

It is known that damage tolerant analysis has two objectives, namely, remaining life prediction and residual strength evaluation. To achieve the these objectives, determination of accurate and reliable fracture parameter is very important. XFEM methodologies for fatigue and fracture analysis of cracked aluminium panels repaired with different patch shapes made of single boron/epoxy have been developed. Heaviside and asymptotic crack tip enrichment functions are employed to model the crack. XFEM formulations such as displacement field formulation and element stiffness matrix formulation are presented. Domain form of interaction integral is employed to determine Stress Intensity Factor of repaired cracked panels. Computed SIFs are incorporated in Paris crack growth model to predict the remaining fatigue life. The residual strength has been computed by using the remaining life approach, which accounts for both crack growth constants and no. of cycles to failure. From the various studies conducted, it is observed that repaired panels have significant effect on reduction of the SIF at the crack tip and hence residual strength as well as remaining life of the patched cracked panels are improved significantly. The predicted remaining life and residual strength will be useful for design of structures/components under fatigue loading.

A control-oriented lithium-ion battery pack model for plug-in hybrid electric vehicle cycle-life studies and system design with consideration of health management

NASA Astrophysics Data System (ADS)

Cordoba-Arenas, Andrea; Onori, Simona; Rizzoni, Giorgio

2015-04-01

A crucial step towards the large-scale introduction of plug-in hybrid electric vehicles (PHEVs) in the market is to reduce the cost of its battery systems. Currently, battery cycle- and calendar-life represents one of the greatest uncertainties in the total life-cycle cost of battery systems. The field of battery aging modeling and prognosis has seen progress with respect to model-based and data-driven approaches to describe the aging of battery cells. However, in real world applications cells are interconnected and aging propagates. The propagation of aging from one cell to others exhibits itself in a reduced battery system life. This paper proposes a control-oriented battery pack model that describes the propagation of aging and its effect on the life span of battery systems. The modeling approach is such that it is able to predict pack aging, thermal, and electrical dynamics under actual PHEV operation, and includes consideration of random variability of the cells, electrical topology and thermal management. The modeling approach is based on the interaction between dynamic system models of the electrical and thermal dynamics, and dynamic models of cell aging. The system-level state-of-health (SOH) is assessed based on knowledge of individual cells SOH, pack electrical topology and voltage equalization approach.

NASALife-Component Fatigue and Creep Life Prediction Program and Illustrative Examples

NASA Technical Reports Server (NTRS)

Murthy, Pappu L. N.; Mital, Subodh K.; Gyekenyesi, John Z.

2005-01-01

NASALife is a life prediction program for propulsion system components made of ceramic matrix composites (CMC) under cyclic thermo-mechanical loading and creep rupture conditions. Although, the primary focus was for CMC components the underlying methodologies are equally applicable to other material systems as well. The program references data for low cycle fatigue (LCF), creep rupture, and static material properties as part of the life prediction process. Multiaxial stresses are accommodated by Von Mises based methods and a Walker model is used to address mean stress effects. Varying loads are reduced by the Rainflow counting method. Lastly, damage due to cyclic loading (Miner s rule) and creep are combined to determine the total damage per mission and the number of missions the component can survive before failure are calculated. Illustration of code usage is provided through example problem of a CMC turbine stator vane made of melt-infiltrated, silicon carbide fiber-reinforced, silicon carbide matrix composite (MI SiC/SiC)

Thermal barrier coating life prediction model development

NASA Technical Reports Server (NTRS)

Hillery, R. V.; Pilsner, B. H.; Mcknight, R. L.; Cook, T. S.; Hartle, M. S.

1988-01-01

This report describes work performed to determine the predominat modes of degradation of a plasma sprayed thermal barrier coating system and to develop and verify life prediction models accounting for these degradation modes. The primary TBC system consisted of a low pressure plasma sprayed NiCrAlY bond coat, an air plasma sprayed ZrO2-Y2O3 top coat, and a Rene' 80 substrate. The work was divided into 3 technical tasks. The primary failure mode to be addressed was loss of the zirconia layer through spalling. Experiments showed that oxidation of the bond coat is a significant contributor to coating failure. It was evident from the test results that the species of oxide scale initially formed on the bond coat plays a role in coating degradation and failure. It was also shown that elevated temperature creep of the bond coat plays a role in coating failure. An empirical model was developed for predicting the test life of specimens with selected coating, specimen, and test condition variations. In the second task, a coating life prediction model was developed based on the data from Task 1 experiments, results from thermomechanical experiments performed as part of Task 2, and finite element analyses of the TBC system during thermal cycles. The third and final task attempted to verify the validity of the model developed in Task 2. This was done by using the model to predict the test lives of several coating variations and specimen geometries, then comparing these predicted lives to experimentally determined test lives. It was found that the model correctly predicts trends, but that additional refinement is needed to accurately predict coating life.

Exploring the universal ecological responses to climate change in a univoltine butterfly.

PubMed

Fenberg, Phillip B; Self, Angela; Stewart, John R; Wilson, Rebecca J; Brooks, Stephen J

2016-05-01

Animals with distinct life stages are often exposed to different temperatures during each stage. Thus, how temperature affects these life stages should be considered for broadly understanding the ecological consequences of climate warming on such species. For example, temperature variation during particular life stages may affect respective change in body size, phenology and geographic range, which have been identified as the "universal" ecological responses to climate change. While each of these responses has been separately documented across a number of species, it is not known whether each response occurs together within a species. The influence of temperature during particular life stages may help explain each of these ecological responses to climate change. Our goal was to determine if monthly temperature variation during particular life stages of a butterfly species can predict respective changes in body size and phenology. We also refer to the literature to assess if temperature variability during the adult stage influences range change over time. Using historical museum collections paired with monthly temperature records, we show that changes in body size and phenology of the univoltine butterfly, Hesperia comma, are partly dependent upon temporal variation in summer temperatures during key stages of their life cycle. June temperatures, which are likely to affect growth rate of the final larval instar, are important for predicting adult body size (for males only; showing a positive relationship with temperature). July temperatures, which are likely to influence the pupal stage, are important for predicting the timing of adult emergence (showing a negative relationship with temperature). Previous studies show that August temperatures, which act on the adult stage, are linked to range change. Our study highlights the importance of considering temperature variation during each life stage over historic time-scales for understanding intraspecific response to climate change. Range edge studies of ectothermic species that have annual life cycles, long time-series occurrence data, and associated temperature records (ideally at monthly resolutions) could be useful model systems for intraspecific tests of the universal ecological responses to climate change and for exploring interactive effects. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

Life duration of Ni-MH cells for high power applications

NASA Astrophysics Data System (ADS)

Le Guenne, Laure; Bernard, Patrick

Intensive research and development carried out at SAFT Research [1,2] has shown that limitation of Ni-MH battery life duration can be directly linked to AB 5 alloy corrosion in the negative electrode. A mathematical model taking into account these results has been developed in order to predict battery life as a function of the conditions of utilisation: cycle and calendar life [3]. However, the degradation of the negative electrode is the consequence of two phenomena: surface corrosion of the active alloy and decrepitation of alloy particles during cycling. Up to now, only the kinetic law controlling the evolution of the thickness of the corrosion layer could have been quantified [3]. On the other hand, the kinetic law of decrepitation could not be directly measured, but is only fitted by determining the total amount of corrosion. Thus, an in situ method suitable to quantify the electrochemical surface of the alloy has been developed. Therefore, electrochemical impedance spectroscopy (EIS) has been used to follow the degradation of the negative electrode, as a function of depth of discharge (DOD) during cycling. Alloy corrosion measurements and scanning electron microscope (SEM) analyses have been performed to confirm the validity of the method. It has been found that decrepitation is nearly zero for low levels of low DOD (5%).

How have fisheries affected parasite communities?

USGS Publications Warehouse

Wood, Chelsea L.; Lafferty, Kevin D.

2015-01-01

To understand how fisheries affect parasites, we conducted a meta-analysis of studies that contrasted parasite assemblages in fished and unfished areas. Parasite diversity was lower in hosts from fished areas. Larger hosts had a greater abundance of parasites, suggesting that fishing might reduce the abundance of parasites by selectively removing the largest, most heavily parasitized individuals. After controlling for size, the effect of fishing on parasite abundance varied according to whether the host was fished and the parasite's life cycle. Parasites of unfished hosts were more likely to increase in abundance in response to fishing than were parasites of fished hosts, possibly due to compensatory increases in the abundance of unfished hosts. While complex life cycle parasites tended to decline in abundance in response to fishing, directly transmitted parasites tended to increase. Among complex life cycle parasites, those with fished hosts tended to decline in abundance in response to fishing, while those with unfished hosts tended to increase. However, among directly transmitted parasites, responses did not differ between parasites with and without fished hosts. This work suggests that parasite assemblages are likely to change substantially in composition in increasingly fished ecosystems, and that parasite life history and fishing status of the host are important in predicting the response of individual parasite species or groups to fishing.

Waste-to-energy: A review of life cycle assessment and its extension methods.

PubMed

Zhou, Zhaozhi; Tang, Yuanjun; Chi, Yong; Ni, Mingjiang; Buekens, Alfons

2018-01-01

This article proposes a comprehensive review of evaluation tools based on life cycle thinking, as applied to waste-to-energy. Habitually, life cycle assessment is adopted to assess environmental burdens associated with waste-to-energy initiatives. Based on this framework, several extension methods have been developed to focus on specific aspects: Exergetic life cycle assessment for reducing resource depletion, life cycle costing for evaluating its economic burden, and social life cycle assessment for recording its social impacts. Additionally, the environment-energy-economy model integrates both life cycle assessment and life cycle costing methods and judges simultaneously these three features for sustainable waste-to-energy conversion. Life cycle assessment is sufficiently developed on waste-to-energy with concrete data inventory and sensitivity analysis, although the data and model uncertainty are unavoidable. Compared with life cycle assessment, only a few evaluations are conducted to waste-to-energy techniques by using extension methods and its methodology and application need to be further developed. Finally, this article succinctly summarises some recommendations for further research.

High temperature fatigue behavior of Haynes 188

NASA Technical Reports Server (NTRS)

Halford, Gary R.; Saltsman, James F.; Kalluri, Sreeramesh

1988-01-01

The high temperature, creep-fatigue behavior of Haynes 188 was investigated as an element in a broader thermomechanical fatigue life prediction model development program at the NASA-Lewis. The models are still in the development stage, but the data that were generated possess intrinsic value on their own. Results generated to date is reported. Data were generated to characterize isothermal low cycle fatigue resistance at temperatures of 316, 704, and 927 C with cyclic failure lives ranging from 10 to more than 20,000. These results follow trends that would be predicted from a knowledge of tensile properties, i.e., as the tensile ductility varies with temperature, so varies the cyclic inelastic straining capacity. Likewise, as the tensile strength decreases, so does the high cyclic fatigue resistance. A few two-minute hold-time cycles at peak compressive strain were included in tests at 760 C. These results were obtained in support of a redesign effort for the Orbital Maneuverable System engine. No detrimental effects on cyclic life were noted despite the added exposure time for creep and oxidation. Finally, a series of simulated thermal fatigue tests, referred to as bithermal fatigue tests, were conducted using 316 C as the minimum and 760 C as the maximum temperature. Only out-of-phase bithermal tests were conducted to date. These test results are intended for use as input to a more general thermomechanical fatigue life prediction model based on the concepts of the total strain version of Strainrange Partitioning.

Using ABAQUS Scripting Interface for Materials Evaluation and Life Prediction

NASA Technical Reports Server (NTRS)

Powers, Lynn M.; Arnold, Steven M.; Baranski, Andrzej

2006-01-01

An ABAQUS script has been written to aid in the evaluation of the mechanical behavior of viscoplastic materials. The purposes of the script are to: handle complex load histories; control load/displacement with alternate stopping criteria; predict failure and life; and verify constitutive models. Material models from the ABAQUS library may be used or the UMAT routine may specify mechanical behavior. User subroutines implemented include: UMAT for the constitutive model; UEXTERNALDB for file manipulation; DISP for boundary conditions; and URDFIL for results processing. Examples presented include load, strain and displacement control tests on a single element model. The tests are creep with a life limiting strain criterion, strain control with a stress limiting cycle and a complex interrupted cyclic relaxation test. The techniques implemented in this paper enable complex load conditions to be solved efficiently with ABAQUS.

Tensile and fatigue data for irradiated and unirradiated AISI 310 stainless steel and titanium - 5 percent aluminum - 2.5 percent tin: Application of the method of universal slopes

NASA Technical Reports Server (NTRS)

Debogdan, C. E.

1973-01-01

Irradiated and unirradiated tensile and fatigue specimens of AISI 310 stainless steel and Ti-5Al-2.5Sn were tested in the range of 100 to 10,000 cycles to failure to determine the applicability of the method of universal slopes to irradiated materials. Tensile data for both materials showed a decrease in ductility and increase in ultimate tensile strength due to irradiation. Irradiation caused a maximum change in fatigue life of only 15 to 20 percent for both materials. The method of universal slopes predicted all the fatigue data for the 310 SS (irradiated as well as unirradiated) within a life factor of 2. For the titanium alloy, 95 percent of the data was predicted within a life factor of 3.

Accounting for indirect land-use change in the life cycle assessment of biofuel supply chains

PubMed Central

Sanchez, Susan Tarka; Woods, Jeremy; Akhurst, Mark; Brander, Matthew; O'Hare, Michael; Dawson, Terence P.; Edwards, Robert; Liska, Adam J.; Malpas, Rick

2012-01-01

The expansion of land used for crop production causes variable direct and indirect greenhouse gas emissions, and other economic, social and environmental effects. We analyse the use of life cycle analysis (LCA) for estimating the carbon intensity of biofuel production from indirect land-use change (ILUC). Two approaches are critiqued: direct, attributional life cycle analysis and consequential life cycle analysis (CLCA). A proposed hybrid ‘combined model’ of the two approaches for ILUC analysis relies on first defining the system boundary of the resulting full LCA. Choices are then made as to the modelling methodology (economic equilibrium or cause–effect), data inputs, land area analysis, carbon stock accounting and uncertainty analysis to be included. We conclude that CLCA is applicable for estimating the historic emissions from ILUC, although improvements to the hybrid approach proposed, coupled with regular updating, are required, and uncertainly values must be adequately represented; however, the scope and the depth of the expansion of the system boundaries required for CLCA remain controversial. In addition, robust prediction, monitoring and accounting frameworks for the dynamic and highly uncertain nature of future crop yields and the effectiveness of policies to reduce deforestation and encourage afforestation remain elusive. Finally, establishing compatible and comparable accounting frameworks for ILUC between the USA, the European Union, South East Asia, Africa, Brazil and other major biofuel trading blocs is urgently needed if substantial distortions between these markets, which would reduce its application in policy outcomes, are to be avoided. PMID:22467143

Accounting for indirect land-use change in the life cycle assessment of biofuel supply chains.

PubMed

Sanchez, Susan Tarka; Woods, Jeremy; Akhurst, Mark; Brander, Matthew; O'Hare, Michael; Dawson, Terence P; Edwards, Robert; Liska, Adam J; Malpas, Rick

2012-06-07

The expansion of land used for crop production causes variable direct and indirect greenhouse gas emissions, and other economic, social and environmental effects. We analyse the use of life cycle analysis (LCA) for estimating the carbon intensity of biofuel production from indirect land-use change (ILUC). Two approaches are critiqued: direct, attributional life cycle analysis and consequential life cycle analysis (CLCA). A proposed hybrid 'combined model' of the two approaches for ILUC analysis relies on first defining the system boundary of the resulting full LCA. Choices are then made as to the modelling methodology (economic equilibrium or cause-effect), data inputs, land area analysis, carbon stock accounting and uncertainty analysis to be included. We conclude that CLCA is applicable for estimating the historic emissions from ILUC, although improvements to the hybrid approach proposed, coupled with regular updating, are required, and uncertainly values must be adequately represented; however, the scope and the depth of the expansion of the system boundaries required for CLCA remain controversial. In addition, robust prediction, monitoring and accounting frameworks for the dynamic and highly uncertain nature of future crop yields and the effectiveness of policies to reduce deforestation and encourage afforestation remain elusive. Finally, establishing compatible and comparable accounting frameworks for ILUC between the USA, the European Union, South East Asia, Africa, Brazil and other major biofuel trading blocs is urgently needed if substantial distortions between these markets, which would reduce its application in policy outcomes, are to be avoided.

Moist Baroclinic Life Cycles in an Idealized Model with Varying Hydrostasy

NASA Astrophysics Data System (ADS)

Hsieh, T. L.; Garner, S.; Held, I.

2016-12-01

Baroclinic life cycles are simulated in a limited-area model having varying degrees of hydrostasy to examine their interaction with explicitly resolved moist convection. The life cycles are driven by an idealized sea surface temperature field in an f-plane channel, and no convective parameterization is used. The hydrostasy is controlled by rescaling the model equations following the hypohydrostatic rescaling and by changing the resolution. In experiments having the same ratio between the grid spacing and the rescaling factor, the simulated convection is shown to have the same hydrostasy, suggesting that the low resolution models have been rescaled to be as nonhydrostatic as the high resolution model without additional computational cost. The nonhydrostatic convective cells in the rescaled models are found to be wider and slower than those in the unscaled models, consistent with predictions of the similarity theory. For the same resolution, although the wider cells in the rescaled models have better resolved structure, the total latent heating is insensitive to the rescaling factor. This is because latent heating is constrained by long-wave cooling which is found to be insensitive to the model hydrostasy, requiring a non-similarity in the frequency and distribution of convection. Consequently, the resolved nonhydrostatic convection maintains the same stability profile as the unresolved hydrostatic convection, so the statistics of the life cycles are also insensitive to the rescaling factor. The findings suggest that the mean climate and internal variability would be unaffected by the hypohydrostatic rescaling when the self-organization of convection is not important.

10 CFR 436.12 - Life cycle cost methodology.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 3 2012-01-01 2012-01-01 false Life cycle cost methodology. 436.12 Section 436.12 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION FEDERAL ENERGY MANAGEMENT AND PLANNING PROGRAMS Methodology and Procedures for Life Cycle Cost Analyses § 436.12 Life cycle cost methodology. The life cycle cost methodology...

10 CFR 436.12 - Life cycle cost methodology.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 3 2014-01-01 2014-01-01 false Life cycle cost methodology. 436.12 Section 436.12 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION FEDERAL ENERGY MANAGEMENT AND PLANNING PROGRAMS Methodology and Procedures for Life Cycle Cost Analyses § 436.12 Life cycle cost methodology. The life cycle cost methodology...

10 CFR 436.12 - Life cycle cost methodology.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 3 2013-01-01 2013-01-01 false Life cycle cost methodology. 436.12 Section 436.12 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION FEDERAL ENERGY MANAGEMENT AND PLANNING PROGRAMS Methodology and Procedures for Life Cycle Cost Analyses § 436.12 Life cycle cost methodology. The life cycle cost methodology...

10 CFR 436.12 - Life cycle cost methodology.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Life cycle cost methodology. 436.12 Section 436.12 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION FEDERAL ENERGY MANAGEMENT AND PLANNING PROGRAMS Methodology and Procedures for Life Cycle Cost Analyses § 436.12 Life cycle cost methodology. The life cycle cost methodology...

10 CFR 436.19 - Life cycle costs.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 3 2011-01-01 2011-01-01 false Life cycle costs. 436.19 Section 436.19 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION FEDERAL ENERGY MANAGEMENT AND PLANNING PROGRAMS Methodology and Procedures for Life Cycle Cost Analyses § 436.19 Life cycle costs. Life cycle costs are the sum of the...

10 CFR 436.12 - Life cycle cost methodology.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 3 2011-01-01 2011-01-01 false Life cycle cost methodology. 436.12 Section 436.12 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION FEDERAL ENERGY MANAGEMENT AND PLANNING PROGRAMS Methodology and Procedures for Life Cycle Cost Analyses § 436.12 Life cycle cost methodology. The life cycle cost methodology...

10 CFR 436.19 - Life cycle costs.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Life cycle costs. 436.19 Section 436.19 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION FEDERAL ENERGY MANAGEMENT AND PLANNING PROGRAMS Methodology and Procedures for Life Cycle Cost Analyses § 436.19 Life cycle costs. Life cycle costs are the sum of the...

The evolution of life cycle complexity in aphids: Ecological optimization or historical constraint?

PubMed

Hardy, Nate B; Peterson, Daniel A; von Dohlen, Carol D

2015-06-01

For decades, biologists have debated why many parasites have obligate multihost life cycles. Here, we use comparative phylogenetic analyses of aphids to evaluate the roles of ecological optimization and historical constraint in the evolution of life cycle complexity. If life cycle complexity is adaptive, it should be evolutionarily labile, that is, change in response to selection. We provide evidence that this is true in some aphids (aphidines), but not others (nonaphidines)-groups that differ in the intensity of their relationships with primary hosts. Next, we test specific mechanisms by which life cycle complexity could be adaptive or a constraint. We find that among aphidines there is a strong association between complex life cycles and polyphagy but only a weak correlation between life cycle complexity and reproductive mode. In contrast, among nonaphidines the relationship between life cycle complexity and host breadth is weak but the association between complex life cycles and sexual reproduction is strong. Thus, although the adaptiveness of life cycle complexity appears to be lineage specific, across aphids, life cycle evolution appears to be tightly linked with the evolution of other important natural history traits. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

A climate sensitive model of carbon transfer through atmosphere, vegetation and soil in managed forest ecosystems

NASA Astrophysics Data System (ADS)

Loustau, D.; Moreaux, V.; Bosc, A.; Trichet, P.; Kumari, J.; Rabemanantsoa, T.; Balesdent, J.; Jolivet, C.; Medlyn, B. E.; Cavaignac, S.; Nguyen-The, N.

2012-12-01

For predicting the future of the forest carbon cycle in forest ecosystems, it is necessary to account for both the climate and management impacts. Climate effects are significant not only at a short time scale but also at the temporal horizon of a forest life cycle e.g. through shift in atmospheric CO2 concentration, temperature and precipitation regimes induced by the enhanced greenhouse effect. Intensification of forest management concerns an increasing fraction of temperate and tropical forests and untouched forests represents only one third of the present forest area. Predicting tools are therefore needed to project climate and management impacts over the forest life cycle and understand the consequence of management on the forest ecosystem carbon cycle. This communication summarizes the structure, main components and properties of a carbon transfer model that describes the processes controlling the carbon cycle of managed forest ecosystems. The model, GO+, links three main components, (i) a module describing the vegetation-atmosphere mass and energy exchanges in 3D, (ii) a plant growth module and a (iii) soil carbon dynamics module in a consistent carbon scheme of transfer from atmosphere back into the atmosphere. It was calibrated and evaluated using observed data collected on coniferous and broadleaved forest stands. The model predicts the soil, water and energy balance of entire rotations of managed stands from the plantation to the final cut and according to a range of management alternatives. It accounts for the main soil and vegetation management operations such as soil preparation, understorey removal, thinnings and clearcutting. Including the available knowledge on the climatic sensitivity of biophysical and biogeochemical processes involved in atmospheric exchanges and carbon cycle of forest ecosystems, GO+ can produce long-term backward or forward simulations of forest carbon and water cycles under a range of climate and management scenarios. This model applications to the prediction and analysis of climate scenarios impacts on southwestern European forests underlines the role of management alternatives, precipitation regime, CO2 concentration and atmospheric humidity .Frequency of soil preparation operations and understorey management play a major role in controlling the net carbon flux into the atmosphere at the juvenile stage ( 0 to 10 y-old) whereas climate and rotation duration control the functioning of adult phase. The model predicts that a drier and warmer climate will reduce the forest productivity and deplete soil and carbon stocks in managed forest from Southwestern Europe within decades, such effects being amplified for most intensive management alternatives. This work was part of the European research project GHG-Europe (EU contract No. 244122) and the French national project FAST co-funded by the Ecology, Agriculture and Forestry Ministries and the Region Aquitaine.

A Novel Creep-Fatigue Life Prediction Model for P92 Steel on the Basis of Cyclic Strain Energy Density

NASA Astrophysics Data System (ADS)

Ji, Dongmei; Ren, Jianxing; Zhang, Lai-Chang

2016-11-01

A novel creep-fatigue life prediction model was deduced based on an expression of the strain energy density in this study. In order to obtain the expression of the strain energy density, the load-controlled creep-fatigue (CF) tests of P92 steel at 873 K were carried out. Cyclic strain of P92 steel under CF load was divided into elastic strain, applying and unloading plastic strain, creep strain, and anelastic strain. Analysis of cyclic strain indicates that the damage process of P92 steel under CF load consists of three stages, similar to pure creep. According to the characteristics of the strains above, an expression was defined to describe the strain energy density for each cycle. The strain energy density at stable stage is inversely proportional to the total strain energy density dissipated by P92 steel. However, the total strain energy densities under different test conditions are proportional to the fatigue life. Therefore, the expression of the strain energy density at stable stage was chosen to predict the fatigue life. The CF experimental data on P92 steel were employed to verify the rationality of the novel model. The model obtained from the load-controlled CF test of P92 steel with short holding time could predict the fatigue life of P92 steel with long holding time.

Estimating Stage Specific Vital Rate Responses to Stress Within Mixed Age Populations of the Opossum Shrimp Americamysis bahia Using Digital Imaging

EPA Science Inventory

Most observations of stressor effects on marine crustaceans are made on individuals or even-aged cohorts. Results of these studies are difficult to translate into ecological predictions, either because life cycle models are incomplete, or because stressor effects on mixed age po...

Crop development related to temperature and photoperiod in temperate cereals

USDA-ARS?s Scientific Manuscript database

Plant development, or the progression of plants through their life cycle, has been of great interest in human history because of the need to know and predict when the harvested part of the plant was at the optimum stage. This knowledge was especially important (even vital) in medicinal plants, where...

Predicting and Mapping Potential Whooping Crane Stopover Habitat to Guide Site Selection for Wind Energy Projects

EPA Science Inventory

Migration is one of the most poorly understood components of a bird’s life cycle. For that reason, migratory stopover habitats are often not part of conservation planning and may be overlooked when planning new development projects. This project highlights and addresses an overl...

Weather in Your Life.

ERIC Educational Resources Information Center

Kannegieter, Sandy; Wirkler, Linda

Facts and activities related to weather and meteorology are presented in this unit. Separate sections cover the following topics: (1) the water cycle; (2) clouds; (3) the Beaufort Scale for rating the speed and force of wind; (4) the barometer; (5) weather prediction; (6) fall weather in Iowa (sleet, frost, and fog); (7) winter weather in Iowa…

Income Transfers and Assets of the Poor. Revised. Discussion Paper.

ERIC Educational Resources Information Center

Ziliak, James P.

Contrary to the predictions of the standard life-cycle model, many low lifetime-income households accumulate little wealth relative to their incomes compared to households with high lifetime income. This paper uses data from the Panel Study of Income Dynamics and a correlated random-effects generalized model of moments estimator to decompose the…

The multiaxial fatigue response of cylindrical geometry under proportional loading subject to fluctuating tractions

NASA Astrophysics Data System (ADS)

Martinez, Rudy D.

A multiaxial fatigue model is proposed, as it would apply to cylindrical geometry in the form of industrial sized pressure vessels. The main focus of the multiaxial fatigue model will be based on using energy methods with the loading states confined to fluctuating tractions under proportional loading. The proposed fatigue model is an effort to support and enhance existing fatigue life predicting methods for pressure vessel design, beyond the ASME Boiler and Pressure Vessel codes, ASME Section VIII Division 2 and 3, which is currently used in industrial engineering practice for pressure vessel design. Both uniaxial and biaxial low alloy pearlittic-ferritic steel cylindrical cyclic test data are utilized to substantiate the proposed fatigue model. Approximate material hardening and softening aspects from applied load cycling states and the Bauschinger effect are accounted for by adjusting strain control generated hysteresis loops and the cyclic stress strain curve. The proposed fatigue energy model and the current ASME fatigue model are then compared with regards to the accuracy of predicting fatigue life cycle consistencies.

Life prediction of expulsion bladders through fatigue test and fold strain analysis

NASA Technical Reports Server (NTRS)

Chu, H. N.; Unterberg, W.

1972-01-01

Cycle life data are presented in terms of true maximum strain for four metals, two plastics, and two elastomers. The Coffin-Manson fatigue theory was applied for metals and plastics, and cut-growth fatigue theory for elastomers. The data are based on measurements made at room and elevated temperatures. It was found that double folds give rise to far severer folding strains than do simple folds. It was also found that, except for the elastomers, all the bladder materials develop surface cracks due to double folds after only one cycle. The findings indicate that metals, which are bets for premeation resistance, are worst for fatigue resistance, and vice versa for elastomers. The intermediate plastics were found to be unsatisfactory for both permeation and fatigue resistance for missions of extended duration.

A New Energy-Critical Plane Damage Parameter for Multiaxial Fatigue Life Prediction of Turbine Blades.

PubMed

Yu, Zheng-Yong; Zhu, Shun-Peng; Liu, Qiang; Liu, Yunhan

2017-05-08

As one of fracture critical components of an aircraft engine, accurate life prediction of a turbine blade to disk attachment is significant for ensuring the engine structural integrity and reliability. Fatigue failure of a turbine blade is often caused under multiaxial cyclic loadings at high temperatures. In this paper, considering different failure types, a new energy-critical plane damage parameter is proposed for multiaxial fatigue life prediction, and no extra fitted material constants will be needed for practical applications. Moreover, three multiaxial models with maximum damage parameters on the critical plane are evaluated under tension-compression and tension-torsion loadings. Experimental data of GH4169 under proportional and non-proportional fatigue loadings and a case study of a turbine disk-blade contact system are introduced for model validation. Results show that model predictions by Wang-Brown (WB) and Fatemi-Socie (FS) models with maximum damage parameters are conservative and acceptable. For the turbine disk-blade contact system, both of the proposed damage parameters and Smith-Watson-Topper (SWT) model show reasonably acceptable correlations with its field number of flight cycles. However, life estimations of the turbine blade reveal that the definition of the maximum damage parameter is not reasonable for the WB model but effective for both the FS and SWT models.

A New Energy-Critical Plane Damage Parameter for Multiaxial Fatigue Life Prediction of Turbine Blades

PubMed Central

Yu, Zheng-Yong; Zhu, Shun-Peng; Liu, Qiang; Liu, Yunhan

2017-01-01

As one of fracture critical components of an aircraft engine, accurate life prediction of a turbine blade to disk attachment is significant for ensuring the engine structural integrity and reliability. Fatigue failure of a turbine blade is often caused under multiaxial cyclic loadings at high temperatures. In this paper, considering different failure types, a new energy-critical plane damage parameter is proposed for multiaxial fatigue life prediction, and no extra fitted material constants will be needed for practical applications. Moreover, three multiaxial models with maximum damage parameters on the critical plane are evaluated under tension-compression and tension-torsion loadings. Experimental data of GH4169 under proportional and non-proportional fatigue loadings and a case study of a turbine disk-blade contact system are introduced for model validation. Results show that model predictions by Wang-Brown (WB) and Fatemi-Socie (FS) models with maximum damage parameters are conservative and acceptable. For the turbine disk-blade contact system, both of the proposed damage parameters and Smith-Watson-Topper (SWT) model show reasonably acceptable correlations with its field number of flight cycles. However, life estimations of the turbine blade reveal that the definition of the maximum damage parameter is not reasonable for the WB model but effective for both the FS and SWT models. PMID:28772873

Life prediction methodology for thermal-mechanical fatigue and elevated temperature creep design

NASA Astrophysics Data System (ADS)

Annigeri, Ravindra

Nickel-based superalloys are used for hot section components of gas turbine engines. Life prediction techniques are necessary to assess service damage in superalloy components resulting from thermal-mechanical fatigue (TMF) and elevated temperature creep. A new TMF life model based on continuum damage mechanics has been developed and applied to IN 738 LC substrate material with and without coating. The model also characterizes TMF failure in bulk NiCoCrAlY overlay and NiAl aluminide coatings. The inputs to the TMF life model are mechanical strain range, hold time, peak cycle temperatures and maximum stress measured from the stabilized or mid-life hysteresis loops. A viscoplastic model is used to predict the stress-strain hysteresis loops. A flow rule used in the viscoplastic model characterizes the inelastic strain rate as a function of the applied stress and a set of three internal stress variables known as back stress, drag stress and limit stress. Test results show that the viscoplastic model can reasonably predict time-dependent stress-strain response of the coated material and stress relaxation during hold times. In addition to the TMF life prediction methodology, a model has been developed to characterize the uniaxial and multiaxial creep behavior. An effective stress defined as the applied stress minus the back stress is used to characterize the creep recovery and primary creep behavior. The back stress has terms representing strain hardening, dynamic recovery and thermal recovery. Whenever the back stress is greater than the applied stress, the model predicts a negative creep rate observed during multiple stress and multiple temperature cyclic tests. The model also predicted the rupture time and the remaining life that are important for life assessment. The model has been applied to IN 738 LC, Mar-M247, bulk NiCoCrAlY overlay coating and 316 austenitic stainless steel. The proposed model predicts creep response with a reasonable accuracy for wide range of loading cases such as uniaxial tension, tension-torsion and tension-internal pressure loading.

Molecular machinery of signal transduction and cell cycle regulation in Plasmodium.

PubMed

Koyama, Fernanda C; Chakrabarti, Debopam; Garcia, Célia R S

2009-05-01

The regulation of the Plasmodium cell cycle is not understood. Although the Plasmodium falciparum genome is completely sequenced, about 60% of the predicted proteins share little or no sequence similarity with other eukaryotes. This feature impairs the identification of important proteins participating in the regulation of the cell cycle. There are several open questions that concern cell cycle progression in malaria parasites, including the mechanism by which multiple nuclear divisions is controlled and how the cell cycle is managed in all phases of their complex life cycle. Cell cycle synchrony of the parasite population within the host, as well as the circadian rhythm of proliferation, are striking features of some Plasmodium species, the molecular basis of which remains to be elucidated. In this review we discuss the role of indole-related molecules as signals that modulate the cell cycle in Plasmodium and other eukaryotes, and we also consider the possible role of kinases in the signal transduction and in the responses it triggers.

Proteomic Analysis of the Schistosoma mansoni Miracidium.

PubMed

Wang, Tianfang; Zhao, Min; Rotgans, Bronwyn A; Strong, April; Liang, Di; Ni, Guoying; Limpanont, Yanin; Ramasoota, Pongrama; McManus, Donald P; Cummins, Scott F

2016-01-01

Despite extensive control efforts, schistosomiasis continues to be a major public health problem in developing nations in the tropics and sub-tropics. The miracidium, along with the cercaria, both of which are water-borne and free-living, are the only two stages in the life-cycle of Schistosoma mansoni which are involved in host invasion. Miracidia penetrate intermediate host snails and develop into sporocysts, which lead to cercariae that can infect humans. Infection of the snail host by the miracidium represents an ideal point at which to interrupt the parasite's life-cycle. This research focuses on an analysis of the miracidium proteome, including those proteins that are secreted. We have identified a repertoire of proteins in the S. mansoni miracidium at 2 hours post-hatch, including proteases, venom allergen-like proteins, receptors and HSP70, which might play roles in snail-parasite interplay. Proteins involved in energy production and conservation were prevalent, as were proteins predicted to be associated with defence. This study also provides a strong foundation for further understanding the roles that neurohormones play in host-seeking by schistosomes, with the potential for development of novel anthelmintics that interfere with its various life-cycle stages.

Modeling Menstrual Cycle Length and Variability at the Approach of Menopause Using Hierarchical Change Point Models

PubMed Central

Huang, Xiaobi; Elliott, Michael R.; Harlow, Siobán D.

2013-01-01

SUMMARY As women approach menopause, the patterns of their menstrual cycle lengths change. To study these changes, we need to jointly model both the mean and variability of cycle length. Our proposed model incorporates separate mean and variance change points for each woman and a hierarchical model to link them together, along with regression components to include predictors of menopausal onset such as age at menarche and parity. Additional complexity arises from the fact that the calendar data have substantial missingness due to hormone use, surgery, and failure to report. We integrate multiple imputation and time-to event modeling in a Bayesian estimation framework to deal with different forms of the missingness. Posterior predictive model checks are applied to evaluate the model fit. Our method successfully models patterns of women’s menstrual cycle trajectories throughout their late reproductive life and identifies change points for mean and variability of segment length, providing insight into the menopausal process. More generally, our model points the way toward increasing use of joint mean-variance models to predict health outcomes and better understand disease processes. PMID:24729638

Experimental and theoretical investigation of fatigue life in reusable rocket thrust chambers

NASA Technical Reports Server (NTRS)

Hannum, N. P.; Kasper, H. J.; Pavli, A. J.

1976-01-01

During a test program to investigate low-cycle thermal fatigue, 13 rocket combustion chambers were fabricated and cyclically test fired to failure. Six oxygen-free, high-conductivity (OFHC) copper and seven Amzirc chambers were tested. The chamber liners were fabricated of copper or copper alloy and contained milled coolant channels. The chambers were completed by means of an electroformed nickel closeout. The oxidant/fuel ratio for the liquid oxygen and gaseous hydrogen propellants was 6.0. The failures in the OFHC copper chambers were not typical fatigue failures but are described as creep rupture enhanced by ratcheting. The coolant channels bulged toward the chamber centerline, resulting in progressive thinning of the wall during each cycle. The failures in the Amzirc alloy chambers were caused by low-cycle thermal fatigue. The lives were much shorter than were predicted by an analytical structural analysis computer program used in conjunction with fatigue life data from isothermal test specimens, due to the uneven distribution of Zr in the chamber material.

Lithium Ion Testing at NSWC Crane in Support of NASA Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Brown, Harry; Jung, David; Lee, Leonine

2010-01-01

This viewgraph presentation reviews Lithium Ion Cell testing at the Naval Surface Warfare Center in Crane, India. The contents include: 1) Quallion 15 Ahr Lithium-Ion Cells, LEO Life Cycle Test; 2) Lithion 50 Ahr Lithium-Ion Cells, LEO Life Cycle Test; 3) ABSL 5 Ahr Lithium-Ion Battery, LRO-LLO Life Cycle Test, SDO-GEO Life Cycle Test; and 4) A123 40 Ahr Lithium-Ion Battery, GPM Life Cycle Test, MMS Life Cycle Test.

Concepts associated with a unified life cycle analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whelan, Gene; Peffers, Melissa S.; Tolle, Duane A.

There is a risk associated with most things in the world, and all things have a life cycle unto themselves, even brownfields. Many components can be described by a''cycle of life.'' For example, five such components are life-form, chemical, process, activity, and idea, although many more may exist. Brownfields may touch upon several of these life cycles. Each life cycle can be represented as independent software; therefore, a software technology structure is being formulated to allow for the seamless linkage of software products, representing various life-cycle aspects. Because classes of these life cycles tend to be independent of each other,more » the current research programs and efforts do not have to be revamped; therefore, this unified life-cycle paradigm builds upon current technology and is backward compatible while embracing future technology. Only when two of these life cycles coincide and one impacts the other is there connectivity and a transfer of information at the interface. The current framework approaches (e.g., FRAMES, 3MRA, etc.) have a design that is amenable to capturing (1) many of these underlying philosophical concepts to assure backward compatibility of diverse independent assessment frameworks and (2) linkage communication to help transfer the needed information at the points of intersection. The key effort will be to identify (1) linkage points (i.e., portals) between life cycles, (2) the type and form of data passing between life cycles, and (3) conditions when life cycles interact and communicate. This paper discusses design aspects associated with a unified life-cycle analysis, which can support not only brownfields but also other types of assessments.« less

NREL: U.S. Life Cycle Inventory Database Home Page

Science.gov Websites

U.S. Life-Cycle Inventory Database Buildings Research Photo of a green field with an ocean in the background. U.S. Life Cycle Inventory Database NREL and its partners created the U.S. Life Cycle Inventory (LCI) Database to help life cycle assessment (LCA) practitioners answer questions about environmental

NREL: U.S. Life Cycle Inventory Database - User Poll

Science.gov Websites

User Poll In preparation for the 2009 U.S. Life Cycle Inventory (LCI) Data Stakeholder meeting, the interested in life cycle analysis. The results from that poll and information gathered from the stakeholders polling data and feedback from life cycle analysis supporters helped develop the U.S. Life Cycle Inventory

Rearing and estimation of life-cycle parameters of the tubicifid worm Branchiura sowerbyi: application to ecotoxicity testing.

PubMed

Ducrot, Virginie; Péry, Alexandre R R; Quéau, Hervé; Mons, Raphaël; Lafont, Michel; Garric, Jeanne

2007-10-01

This paper provides original collection, acclimatizing, rearing and toxicity test methods for the freshwater worm Branchiura sowerbyi, an alternative species to Tubifex tubifex for ecotoxicity evaluation of sediments. Influence of the substrate, type of food, and feeding level on individual performances was assessed in short-term tests, in order to set up optimal culture and test conditions. Low-size particles and high organic matter content favoured the growth and reproduction of B. sowerbyi. The relative contribution of sediments and fish food to the individual food intake was assessed using a foraging efficiency model based upon the dynamic energy budget theory. Individual performances were optimal when the substrate plus fish food provided the energy equivalent to 5 mg Tetramin per worm per day, which is the ad libitum food level for adults at 21 degrees C. The life-cycle of the worm was fully characterized using a life-cycle test conducted under the previously defined optimal conditions. Hatching rates were low (32%), whereas newborn and juveniles exhibited high survival (>80%) and growth (2.4 mg/day in juveniles) rates. Age at puberty was low (60 days) when compared to the maximal life span (1100 days) as predicted using a Weibull model. Adults reproduced every other month with a constant fecundity (0.16 cocoon/worm/day). The mean values of the life-cycle parameters and their variability and reproducibility among laboratory studies were discussed in order to identify relevant endpoints to be used in ecotoxicity tests. Survival, juvenile growth, and fecundity may constitute suitable test endpoints, whereas hatching rate and adult growth should not be used as endpoints in B. sowerbyi.

Spectrum Fatigue of 7075-T651 Aluminum Alloy under Overloading and Underloading

DTIC Science & Technology

2016-03-15

underload, stress ratio, and environment on fatigue crack growth. Fatigue crack growth tests were conducted with a 7075-T651 aluminum alloy under constant...the UniGrow equation, the variation of crack length with number of loading cycle was predicted. The prediction and the fatigue test life were found to...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39-18 REPORT NO. NAWCADPAX/TIM-2015/282 ii SUMMARY Fatigue tests of 7075-T651

Predicting ecosystem shifts requires new approaches that integrate the effects of climate change across entire systems

PubMed Central

Russell, Bayden D.; Harley, Christopher D. G.; Wernberg, Thomas; Mieszkowska, Nova; Widdicombe, Stephen; Hall-Spencer, Jason M.; Connell, Sean D.

2012-01-01

Most studies that forecast the ecological consequences of climate change target a single species and a single life stage. Depending on climatic impacts on other life stages and on interacting species, however, the results from simple experiments may not translate into accurate predictions of future ecological change. Research needs to move beyond simple experimental studies and environmental envelope projections for single species towards identifying where ecosystem change is likely to occur and the drivers for this change. For this to happen, we advocate research directions that (i) identify the critical species within the target ecosystem, and the life stage(s) most susceptible to changing conditions and (ii) the key interactions between these species and components of their broader ecosystem. A combined approach using macroecology, experimentally derived data and modelling that incorporates energy budgets in life cycle models may identify critical abiotic conditions that disproportionately alter important ecological processes under forecasted climates. PMID:21900317

Is there an environmental benefit from remediation of a contaminated site? Combined assessments of the risk reduction and life cycle impact of remediation.

PubMed

Lemming, Gitte; Chambon, Julie C; Binning, Philip J; Bjerg, Poul L

2012-12-15

A comparative life cycle assessment is presented for four different management options for a trichloroethene-contaminated site with a contaminant source zone located in a fractured clay till. The compared options are (i) long-term monitoring (ii) in-situ enhanced reductive dechlorination (ERD), (iii) in-situ chemical oxidation (ISCO) with permanganate and (iv) long-term monitoring combined with treatment by activated carbon at the nearby waterworks. The life cycle assessment included evaluation of both primary and secondary environmental impacts. The primary impacts are the local human toxic impacts due to contaminant leaching into groundwater that is used for drinking water, whereas the secondary environmental impacts are related to remediation activities such as monitoring, drilling and construction of wells and use of remedial amendments. The primary impacts for the compared scenarios were determined by a numerical risk assessment and remedial performance model, which predicted the contaminant mass discharge over time at a point of compliance in the aquifer and at the waterworks. The combined assessment of risk reduction and life cycle impacts showed that all management options result in higher environmental impacts than they remediate, in terms of person equivalents and assuming equal weighting of all impacts. The ERD and long-term monitoring were the scenarios with the lowest secondary life cycle impacts and are therefore the preferred alternatives. However, if activated carbon treatment at the waterworks is required in the long-term monitoring scenario, then it becomes unfavorable because of large secondary impacts. ERD is favorable due to its low secondary impacts, but only if leaching of vinyl chloride to the groundwater aquifer can be avoided. Remediation with ISCO caused the highest secondary impacts and cannot be recommended for the site. Copyright © 2012 Elsevier Ltd. All rights reserved.

10 CFR 436.19 - Life cycle costs.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 3 2014-01-01 2014-01-01 false Life cycle costs. 436.19 Section 436.19 Energy DEPARTMENT... Procedures for Life Cycle Cost Analyses § 436.19 Life cycle costs. Life cycle costs are the sum of the... (d) Energy and/or water costs. [55 FR 48220, Nov. 20, 1990, as amended at 61 FR 32651, June 25, 1996] ...

10 CFR 436.19 - Life cycle costs.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 3 2013-01-01 2013-01-01 false Life cycle costs. 436.19 Section 436.19 Energy DEPARTMENT... Procedures for Life Cycle Cost Analyses § 436.19 Life cycle costs. Life cycle costs are the sum of the... (d) Energy and/or water costs. [55 FR 48220, Nov. 20, 1990, as amended at 61 FR 32651, June 25, 1996] ...

10 CFR 436.19 - Life cycle costs.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 3 2012-01-01 2012-01-01 false Life cycle costs. 436.19 Section 436.19 Energy DEPARTMENT... Procedures for Life Cycle Cost Analyses § 436.19 Life cycle costs. Life cycle costs are the sum of the... (d) Energy and/or water costs. [55 FR 48220, Nov. 20, 1990, as amended at 61 FR 32651, June 25, 1996] ...

Cyclic fatigue analysis of rocket thrust chambers. Volume 1: OFHC copper chamber low cycle fatigue

NASA Technical Reports Server (NTRS)

Miller, R. W.

1974-01-01

A three-dimensional finite element elasto-plastic strain analysis was performed for the throat section of a regeneratively cooled rocket combustion chamber. The analysis employed the RETSCP finite element computer program. The analysis included thermal and pressure loads, and the effects of temperature dependent material properties, to determine the strain range corresponding to the chamber operating cycle. The analysis was performed for chamber configuration and operating conditions corresponding to a hydrogen-oxygen combustion chamber which was fatigue tested to failure. The computed strain range at typical chamber operating conditions was used in conjunction with oxygen-free, high-conductivity (OHFC) copper isothermal fatigue test data to predict chamber low-cycle fatigue life.

The application of probabilistic design theory to high temperature low cycle fatigue

NASA Technical Reports Server (NTRS)

Wirsching, P. H.

1981-01-01

Metal fatigue under stress and thermal cycling is a principal mode of failure in gas turbine engine hot section components such as turbine blades and disks and combustor liners. Designing for fatigue is subject to considerable uncertainty, e.g., scatter in cycles to failure, available fatigue test data and operating environment data, uncertainties in the models used to predict stresses, etc. Methods of analyzing fatigue test data for probabilistic design purposes are summarized. The general strain life as well as homo- and hetero-scedastic models are considered. Modern probabilistic design theory is reviewed and examples are presented which illustrate application to reliability analysis of gas turbine engine components.

Easy method of matching fighter engine to airframe for use in aircraft engine design courses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mattingly, J.D.

1989-01-01

The proper match of the engine(s) to the airframe affects both aircraft size and life cycle cost. A fast and straightforward method is developed and used for the matching of fighter engine(s) to airframes during conceptual design. A thrust-lapse equation is developed for the dual-spool, mixed-flow, afterburning turbofan type of engine based on the installation losses of 'Aircraft Engine Design' and the performance predictions of the cycle analysis programs ONX and OFFX. Using system performance requirements, the effects of aircraft thrust-to-weight, wing loading, and engine cycle on takeoff weight are analyzed and example design course results presented. 5 refs.

What childhood characteristics predict psychological resilience to economic shocks in adulthood?

PubMed Central

Powdthavee, Nattavudh

2015-01-01

This paper investigates whether people’s psychological resilience to one of the most important economic shocks – job loss – can be predicted using early childhood characteristics. Using a longitudinal data that tracked almost 3000 children into adulthood, we showed that the negative effect of unemployment on mental well-being and life satisfaction is significantly larger for workers who, as adolescents, had a relatively poor father-child relationship. Maternal unemployment, on the other hand, is a good predictor of how individuals react psychologically to future unemployment. Although the results should be viewed as illustrative and more research is needed, the current article provides new longitudinal evidence that psychological resilience to job loss may be determined early on in the life cycle. PMID:26997688

Proof-test-based life prediction of high-toughness pressure vessels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panontin, T.L.; Hill, M.R.

1996-02-01

The paper examines the problems associated with applying proof-test-based life prediction to vessels made of high-toughness metals. Two A106 Gr B pipe specimens containing long, through-wall circumferential flaws were tested. One failed during hydrostatic testing and the other during tension-tension cycling following a hydrostatic test. Quantitative fractography was used to verify experimentally obtained fatigue crack growth rates and a variety of LEFM and EPFM techniques were used to analyze the experimental results. The results show that: plastic collapse analysis provides accurate predictions of screened (initial) crack size when the flow stress is determined experimentally; LEFM analysis underestimates the crack sizemore » screened by the proof test and overpredicts the subsequent fatigue life of the vessel when retardation effects are small (i.e., low proof levels); and, at a high proof-test level (2.4 {times} operating pressure), the large retardation effect on fatigue crack growth due to the overload overwhelmed the deleterious effect on fatigue life from stable tearing during the proof test and alleviated the problem of screening only long cracks due to the high toughness of the metal.« less

Strain-cycling fatigue behavior of ten structural metals tested in liquid helium (4 K), in liquid nitrogen (78 K), and in ambient air (300 K)

NASA Technical Reports Server (NTRS)

Nachtigall, A. J.

1974-01-01

Strain-cycling fatigue behavior of 10 different structural alloys and metals was investigated in liquid helium (4 K), in liquid nitrogen (78 K), and in ambient air (300 K). At high cyclic lives, fatigue resistance increased with decreasing temperature for all the materials investigated. At low cyclic lives, fatigue resistance generally decreased with decreasing temperature for the materials investigated. Only for Inconel 718 did fatigue resistance increase with decreasing temperature over the entire life range investigated. Comparison of the experimental fatigue behavior with that predicted by the Manson method of universal slopes showed that the fatigue behavior of these materials can be predicted for cryogenic temperatures by using material tensile properties obtained at those same temperatures.

10 CFR 435.8 - Life-cycle costing.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 3 2013-01-01 2013-01-01 false Life-cycle costing. 435.8 Section 435.8 Energy DEPARTMENT...-cycle costing. Each Federal agency shall determine life-cycle cost-effectiveness by using the procedures..., including lower life-cycle costs, positive net savings, savings-to-investment ratio that is estimated to be...

10 CFR 435.8 - Life-cycle costing.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 3 2014-01-01 2014-01-01 false Life-cycle costing. 435.8 Section 435.8 Energy DEPARTMENT...-cycle costing. Each Federal agency shall determine life-cycle cost-effectiveness by using the procedures..., including lower life-cycle costs, positive net savings, savings-to-investment ratio that is estimated to be...

10 CFR 435.8 - Life-cycle costing.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 3 2012-01-01 2012-01-01 false Life-cycle costing. 435.8 Section 435.8 Energy DEPARTMENT...-cycle costing. Each Federal agency shall determine life-cycle cost-effectiveness by using the procedures..., including lower life-cycle costs, positive net savings, savings-to-investment ratio that is estimated to be...

Life Prediction of Large Lithium-Ion Battery Packs with Active and Passive Balancing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Ying; Smith, Kandler A; Zane, Regan

Lithium-ion battery packs take a major part of large-scale stationary energy storage systems. One challenge in reducing battery pack cost is to reduce pack size without compromising pack service performance and lifespan. Prognostic life model can be a powerful tool to handle the state of health (SOH) estimate and enable active life balancing strategy to reduce cell imbalance and extend pack life. This work proposed a life model using both empirical and physical-based approaches. The life model described the compounding effect of different degradations on the entire cell with an empirical model. Then its lower-level submodels considered the complex physicalmore » links between testing statistics (state of charge level, C-rate level, duty cycles, etc.) and the degradation reaction rates with respect to specific aging mechanisms. The hybrid approach made the life model generic, robust and stable regardless of battery chemistry and application usage. The model was validated with a custom pack with both passive and active balancing systems implemented, which created four different aging paths in the pack. The life model successfully captured the aging trajectories of all four paths. The life model prediction errors on capacity fade and resistance growth were within +/-3% and +/-5% of the experiment measurements.« less

Bamboo-Dominated Forests of the Southwest Amazon: Detection, Spatial Extent, Life Cycle Length and Flowering Waves

PubMed Central

de Carvalho, Anelena L.; Nelson, Bruce W.; Bianchini, Milton C.; Plagnol, Daniela; Kuplich, Tatiana M.; Daly, Douglas C.

2013-01-01

We map the extent, infer the life-cycle length and describe spatial and temporal patterns of flowering of sarmentose bamboos (Guadua spp) in upland forests of the southwest Amazon. We first examine the spectra and the spectral separation of forests with different bamboo life stages. False-color composites from orbital sensors going back to 1975 are capable of distinguishing life stages. These woody bamboos flower produce massive quantities of seeds and then die. Life stage is synchronized, forming a single cohort within each population. Bamboo dominates at least 161,500 km2 of forest, coincident with an area of recent or ongoing tectonic uplift, rapid mechanical erosion and poorly drained soils rich in exchangeable cations. Each bamboo population is confined to a single spatially continuous patch or to a core patch with small outliers. Using spatial congruence between pairs of mature-stage maps from different years, we estimate an average life cycle of 27–28 y. It is now possible to predict exactly where and approximately when new bamboo mortality events will occur. We also map 74 bamboo populations that flowered between 2001 and 2008 over the entire domain of bamboo-dominated forest. Population size averaged 330 km2. Flowering events of these populations are temporally and/or spatially separated, restricting or preventing gene exchange. Nonetheless, adjacent populations flower closer in time than expected by chance, forming flowering waves. This may be a consequence of allochronic divergence from fewer ancestral populations and suggests a long history of widespread bamboo in the southwest Amazon. PMID:23359438

Physics based modeling of a series parallel battery pack for asymmetry analysis, predictive control and life extension

NASA Astrophysics Data System (ADS)

Ganesan, Nandhini; Basu, Suman; Hariharan, Krishnan S.; Kolake, Subramanya Mayya; Song, Taewon; Yeo, Taejung; Sohn, Dong Kee; Doo, Seokgwang

2016-08-01

Lithium-Ion batteries used for electric vehicle applications are subject to large currents and various operation conditions, making battery pack design and life extension a challenging problem. With increase in complexity, modeling and simulation can lead to insights that ensure optimal performance and life extension. In this manuscript, an electrochemical-thermal (ECT) coupled model for a 6 series × 5 parallel pack is developed for Li ion cells with NCA/C electrodes and validated against experimental data. Contribution of the cathode to overall degradation at various operating conditions is assessed. Pack asymmetry is analyzed from a design and an operational perspective. Design based asymmetry leads to a new approach of obtaining the individual cell responses of the pack from an average ECT output. Operational asymmetry is demonstrated in terms of effects of thermal gradients on cycle life, and an efficient model predictive control technique is developed. Concept of reconfigurable battery pack is studied using detailed simulations that can be used for effective monitoring and extension of battery pack life.

A life cycle database for parasitic acanthocephalans, cestodes, and nematodes

USGS Publications Warehouse

Benesh, Daniel P.; Lafferty, Kevin D.; Kuris, Armand

2017-01-01

Parasitologists have worked out many complex life cycles over the last ~150 years, yet there have been few efforts to synthesize this information to facilitate comparisons among taxa. Most existing host-parasite databases focus on particular host taxa, do not distinguish final from intermediate hosts, and lack parasite life-history information. We summarized the known life cycles of trophically transmitted parasitic acanthocephalans, cestodes, and nematodes. For 973 parasite species, we gathered information from the literature on the hosts infected at each stage of the parasite life cycle (8510 host-parasite species associations), what parasite stage is in each host, and whether parasites need to infect certain hosts to complete the life cycle. We also collected life-history data for these parasites at each life cycle stage, including 2313 development time measurements and 7660 body size measurements. The result is the most comprehensive data summary available for these parasite taxa. In addition to identifying gaps in our knowledge of parasite life cycles, these data can be used to test hypotheses about life cycle evolution, host specificity, parasite life-history strategies, and the roles of parasites in food webs.

Impact of Life-Cycle Stage and Gender on the Ability to Balance Work and Family Responsibilities.

ERIC Educational Resources Information Center

Higgins, Christopher; And Others

1994-01-01

Examined impact of gender and life-cycle stage on three components of work-family conflict using sample of 3,616 respondents. For men, levels of work-family conflict were moderately lower in each successive life-cycle stage. For women, levels were similar in two early life-cycle stages but were significantly lower in later life-cycle stage.…

Thermal barrier coating life prediction model

NASA Technical Reports Server (NTRS)

Hillery, R. V.; Pilsner, B. H.

1985-01-01

This is the first report of the first phase of a 3-year program. Its objectives are to determine the predominant modes of degradation of a plasma sprayed thermal barrier coating system, then to develop and verify life prediction models accounting for these degradation modes. The first task (Task I) is to determine the major failure mechanisms. Presently, bond coat oxidation and bond coat creep are being evaluated as potential TBC failure mechanisms. The baseline TBC system consists of an air plasma sprayed ZrO2-Y2O3 top coat, a low pressure plasma sprayed NiCrAlY bond coat, and a Rene'80 substrate. Pre-exposures in air and argon combined with thermal cycle tests in air and argon are being utilized to evaluate bond coat oxidation as a failure mechanism. Unexpectedly, the specimens pre-exposed in argon failed before the specimens pre-exposed in air in subsequent thermal cycles testing in air. Four bond coats with different creep strengths are being utilized to evaluate the effect of bond coat creep on TBC degradation. These bond coats received an aluminide overcoat prior to application of the top coat to reduce the differences in bond coat oxidation behavior. Thermal cycle testing has been initiated. Methods have been selected for measuring tensile strength, Poisson's ratio, dynamic modulus and coefficient of thermal expansion both of the bond coat and top coat layers.

Energy Dissipation-Based Method for Fatigue Life Prediction of Rock Salt

NASA Astrophysics Data System (ADS)

He, Mingming; Huang, Bingqian; Zhu, Caihui; Chen, Yunsheng; Li, Ning

2018-05-01

The fatigue test for rock salt is conducted under different stress amplitudes, loading frequencies, confining pressures and loading rates, from which the evaluation rule of the dissipated energy is revealed and analysed. The evolution of energy dissipation under fatigue loading is divided into three stages: the initial stage, the second stage and the acceleration stage. In the second stage, the energy dissipation per cycle remains stable and shows an exponential relation with the stress amplitude; the failure dissipated energy only depends on the mechanical behaviour of the rock salt and confining pressure, but it is immune to the loading conditions. The energy dissipation of fatigued rock salt is discussed, and a novel model for fatigue life prediction is proposed on the basis of energy dissipation. A simple model for evolution of the accumulative dissipated energy is established. Its prediction results are compared with the test results, and the proposed model is validated.

Hot fire fatigue testing results for the compliant combustion chamber

NASA Technical Reports Server (NTRS)

Pavli, Albert J.; Kazaroff, John M.; Jankovsky, Robert S.

1992-01-01

A hydrogen-oxygen subscale rocket combustion chamber was designed incorporating an advanced design concept to reduce strain and increase life. The design permits unrestrained thermal expansion of a circumferential direction and, thereby, provides structural compliance during the thermal cycling of hot-fire testing. The chamber was built and test fired at a chamber pressure of 4137 kN/sq m (600 psia) and a hydrogen-oxygen mixture ratio of 6.0. Compared with a conventional milled-channel configuration, the new structurally compliant chamber had a 134 or 287 percent increase in fatigue life, depending on the life predicted for the conventional configuration.

Durability of sealants exposed to outdoor weathering and hot compression cycles

Treesearch

Gregory T. Schueneman; Steven Lacher; Christopher G. Hunt; Christopher C. White; Donald L. Hunston

2011-01-01

Sealants play an important role in weatherproofing structures by filling gaps and preventing air and water intrusion. When incorrectly selected or improperly applied, they may fail quickly, compromising durability of the structure. To ensure reliability and prevent the need for costly repairs to structures, it is necessary to measure durability and predict life...

Environmental Education: A Natural Way to Nurture Children's Development and Learning

ERIC Educational Resources Information Center

Torquati, Julia

2010-01-01

Experiences in the natural world help children understand life cycles and seasons, make prediction and become aware of the interdependence between plants, animals, and elements like rain and sun. Early childhood is a critical time to support children's connections to the natural world because young children are naturally curious and there is so…

Estimating Stage-Specific Vital Rate Responses to Stress within Mixed Age Populations of the Opossum Shrimp Americamysis Bahia Using Digital Imaging (NAC SETAC 2011)

EPA Science Inventory

Most observations of stressor effects on marine crustaceans are made on individuals or even-aged cohorts. Results of these studies are difficult to translate into ecological predictions, either because life cycle models are incomplete, or because stressor effects on mixed age po...

Save More Tomorrow: Using Behavioral Economics to Increase Employee Saving.

ERIC Educational Resources Information Center

Thaler, Richard H.; Benartzi, Shlomo

2004-01-01

As firms switch from defined-benefit plans to defined-contribution plans, employees bear more responsibility for making decisions about how much to save. The employees who fail to join the plan or who participate at a very low level appear to be saving at less than the predicted life cycle savings rates. Behavioral explanations for this behavior…

Design of intelligent composites with life-cycle health management capabilities

NASA Astrophysics Data System (ADS)

Rosania, Colleen L.; Larrosa, Cecilia C.; Chang, Fu-Kuo

2015-03-01

Use of carbon fiber reinforced polymers (CFRPs) presents challenges because of their complex manufacturing processes and different damage mechanics in relation to legacy metal materials. New monitoring methods for manufacturing, quality verification, damage estimation, and prognosis are needed to use CFRPs safely and efficiently. This work evaluates the development of intelligent composite materials using integrated piezoelectric sensors to monitor the material during cure and throughout service life. These sensors are used to propagate ultrasonic waves through the structure for health monitoring. During manufacturing, data is collected at different stages during the cure cycle, detecting the changing material properties during cure and verifying quality and degree of cure. The same sensors can then be used with previously developed techniques to perform damage detection, such as impact detection and matrix crack density estimation. Real-time damage estimation can be combined with prognostic models to predict future propagation of damage in the material. In this work experimental results will be presented from composite coupons with embedded piezoelectric sensors. Cure monitoring and damage detection results derived from analysis of the ultrasonic sensor signal will be shown. Sensitive signal parameters to the different stimuli in both the time and frequency domains will be explored for this analysis. From these results, use of the same sensor networks from manufacturing throughout the life of the composite material will demonstrate the full life-cycle monitoring capability of these intelligent materials.

Lithium-ion battery state of health monitoring and remaining useful life prediction based on support vector regression-particle filter

NASA Astrophysics Data System (ADS)

Dong, Hancheng; Jin, Xiaoning; Lou, Yangbing; Wang, Changhong

2014-12-01

Lithium-ion batteries are used as the main power source in many electronic and electrical devices. In particular, with the growth in battery-powered electric vehicle development, the lithium-ion battery plays a critical role in the reliability of vehicle systems. In order to provide timely maintenance and replacement of battery systems, it is necessary to develop a reliable and accurate battery health diagnostic that takes a prognostic approach. Therefore, this paper focuses on two main methods to determine a battery's health: (1) Battery State-of-Health (SOH) monitoring and (2) Remaining Useful Life (RUL) prediction. Both of these are calculated by using a filter algorithm known as the Support Vector Regression-Particle Filter (SVR-PF). Models for battery SOH monitoring based on SVR-PF are developed with novel capacity degradation parameters introduced to determine battery health in real time. Moreover, the RUL prediction model is proposed, which is able to provide the RUL value and update the RUL probability distribution to the End-of-Life cycle. Results for both methods are presented, showing that the proposed SOH monitoring and RUL prediction methods have good performance and that the SVR-PF has better monitoring and prediction capability than the standard particle filter (PF).

Viscoplastic analysis of an experimental cylindrical thrust chamber liner

NASA Technical Reports Server (NTRS)

Arya, Vinod K.; Arnold, Steven M.

1991-01-01

A viscoplastic stress-strain analysis of an experimental cylindrical thrust chamber is presented. A viscoelastic constitutive model incorporating a single internal state variable that represents kinematic hardening was employed to investigate whether such a viscoplastic model could predict the experimentally observed behavior of the thrust chamber. Two types of loading cycles were considered: a short cycle of 3.5 sec. duration that corresponded to the experiments, and an extended loading cycle of 485.1 sec. duration that is typical of the Space Shuttle Main Engine (SSME) operating cycle. The analysis qualitatively replicated the deformation behavior of the component as observed in experiments designed to simulate SSME operating conditions. The analysis also showed that the mode and location in the component may depend on the loading cycle. The results indicate that using viscoplastic models for structural analysis can lead to a more realistic life assessment of thrust chambers.

Life Cycle of Tropical Convection and Anvil in Observations and Models

NASA Astrophysics Data System (ADS)

McFarlane, S. A.; Hagos, S. M.; Comstock, J. M.

2011-12-01

Tropical convective clouds are important elements of the hydrological cycle and produce extensive cirrus anvils that strongly affect the tropical radiative energy balance. To improve simulations of the global water and energy cycles and accurately predict both precipitation and cloud radiative feedbacks, models need to realistically simulate the lifecycle of tropical convection, including the formation and radiative properties of ice anvil clouds. By combining remote sensing datasets from precipitation and cloud radars at the Atmospheric Radiation Measurement (ARM) Darwin site with geostationary satellite data, we can develop observational understanding of the lifetime of convective systems and the links between the properties of convective systems and their associated anvil clouds. The relationships between convection and anvil in model simulations can then be compared to those seen in the observations to identify areas for improvement in the model simulations. We identify and track tropical convective systems in the Tropical Western Pacific using geostationary satellite observations. We present statistics of the tropical convective systems including size, age, and intensity and classify the lifecycle stage of each system as developing, mature, or dissipating. For systems that cross over the ARM Darwin site, information on convective intensity and anvil properties are obtained from the C-Pol precipitation radar and MMCR cloud radar, respectively, and are examined as a function of the system lifecycle. Initial results from applying the convective identification and tracking algorithm to a tropical simulation from the Weather Research and Forecasting (WRF) model run show that the model produces reasonable overall statistics of convective systems, but details of the life cycle (such as diurnal cycle, system tracks) differ from the observations. Further work will focus on the role of atmospheric temperature and moisture profiles in the model's convective life cycle.

Geographic variation and evolution in the life cycle of the witch-hazel leaf gall aphid, Hormaphis hamamelidis.

PubMed

von Dohlen, C D; Gill, D E

1989-02-01

Two divergent life cycles associated with different elevations and latitudes have been documented for the witch-hazel leaf gall aphid, Hormaphis hamamelidis. At low elevation in northern Virginia, the aphid had seven distinct generations alternating between the primary host, witchhazel (Hamamelis virginiana), and a secondary host, river birch (Betula nigra). These findings confirm the original published life cycle description for the same locality. A second, abbreviated life cycle consisting of only three generations restricted to witch-hazel was discovered at high elevation (1000 m) in north central and northwestern Virginia. Aphids of both life cycles were sympatric at a middle elevation site. The life cycles and morphology suggest that the two forms are separate species. Although monoecious life cycles on primary hosts in aphids generally are thought to be ancestral to complex host-alternating ones, it is certainly possible that monoecious cycles are sometimes secondarily derived from complex cycles. By constructing a preliminary phylogeny of the described species in the tribe Hormaphidini, we propose that the abbreviated life cycle is derived from the complex one in the case of these witchhazel gall aphids. Our findings are discussed in the context of current theory regarding the evolutionary stability of complex life cycles.

32 CFR Appendix to Part 162 - Reporting Procedures

Code of Federal Regulations, 2014 CFR

2014-07-01

... generated. e. Projected Life-Cycle Savings. For each PIF project provide the estimated amount of savings the project is projected to earn over the project's economic life. f. Projected Life-Cycle Cost Avoidance. For... Projected Life-Cycle Savings. e. Total Projected Life-Cycle Cost Avoidance. 3. CSI. Each DoD Component that...

10 CFR 433.8 - Life-cycle costing.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 3 2014-01-01 2014-01-01 false Life-cycle costing. 433.8 Section 433.8 Energy DEPARTMENT... HIGH-RISE RESIDENTIAL BUILDINGS § 433.8 Life-cycle costing. Each Federal agency shall determine life... choose to use any of four methods, including lower life-cycle costs, positive net savings, savings-to...

19 CFR 207.27 - Short life cycle products.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 19 Customs Duties 3 2013-04-01 2013-04-01 false Short life cycle products. 207.27 Section 207.27... SUBSIDIZED EXPORTS TO THE UNITED STATES Final Determinations, Short Life Cycle Products § 207.27 Short life... short life cycle merchandise which has been the subject of two or more affirmative dumping...

10 CFR 433.8 - Life-cycle costing.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 3 2012-01-01 2012-01-01 false Life-cycle costing. 433.8 Section 433.8 Energy DEPARTMENT... HIGH-RISE RESIDENTIAL BUILDINGS § 433.8 Life-cycle costing. Each Federal agency shall determine life... choose to use any of four methods, including lower life-cycle costs, positive net savings, savings-to...

19 CFR 207.27 - Short life cycle products.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 19 Customs Duties 3 2014-04-01 2014-04-01 false Short life cycle products. 207.27 Section 207.27... SUBSIDIZED EXPORTS TO THE UNITED STATES Final Determinations, Short Life Cycle Products § 207.27 Short life... short life cycle merchandise which has been the subject of two or more affirmative dumping...

10 CFR 433.8 - Life-cycle costing.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 3 2013-01-01 2013-01-01 false Life-cycle costing. 433.8 Section 433.8 Energy DEPARTMENT... HIGH-RISE RESIDENTIAL BUILDINGS § 433.8 Life-cycle costing. Each Federal agency shall determine life... choose to use any of four methods, including lower life-cycle costs, positive net savings, savings-to...

19 CFR 207.27 - Short life cycle products.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 19 Customs Duties 3 2012-04-01 2012-04-01 false Short life cycle products. 207.27 Section 207.27... SUBSIDIZED EXPORTS TO THE UNITED STATES Final Determinations, Short Life Cycle Products § 207.27 Short life... short life cycle merchandise which has been the subject of two or more affirmative dumping...

19 CFR 207.27 - Short life cycle products.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 3 2010-04-01 2010-04-01 false Short life cycle products. 207.27 Section 207.27... SUBSIDIZED EXPORTS TO THE UNITED STATES Final Determinations, Short Life Cycle Products § 207.27 Short life... short life cycle merchandise which has been the subject of two or more affirmative dumping...

19 CFR 207.27 - Short life cycle products.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 19 Customs Duties 3 2011-04-01 2011-04-01 false Short life cycle products. 207.27 Section 207.27... SUBSIDIZED EXPORTS TO THE UNITED STATES Final Determinations, Short Life Cycle Products § 207.27 Short life... short life cycle merchandise which has been the subject of two or more affirmative dumping...

Does It Have a Life Cycle?

ERIC Educational Resources Information Center

Keeley, Page

2010-01-01

If life continues from generation to generation, then all plants and animals must go through a life cycle, even though it may be different from organism to organism. Is this what students have "learned," or do they have their own private conceptions about life cycles? The formative assessment probe "Does It Have a Life Cycle?" reveals some…

Comparative analysis of economic models in selected solar energy computer programs

NASA Astrophysics Data System (ADS)

Powell, J. W.; Barnes, K. A.

1982-01-01

The economic evaluation models in five computer programs widely used for analyzing solar energy systems (F-CHART 3.0, F-CHART 4.0, SOLCOST, BLAST, and DOE-2) are compared. Differences in analysis techniques and assumptions among the programs are assessed from the point of view of consistency with the Federal requirements for life cycle costing (10 CFR Part 436), effect on predicted economic performance, and optimal system size, case of use, and general applicability to diverse systems types and building types. The FEDSOL program developed by the National Bureau of Standards specifically to meet the Federal life cycle cost requirements serves as a basis for the comparison. Results of the study are illustrated in test cases of two different types of Federally owned buildings: a single family residence and a low rise office building.

Verification of rain-flow reconstructions of a variable amplitude load history. M.S. Thesis, 1990 Final Report

NASA Technical Reports Server (NTRS)

Clothiaux, John D.; Dowling, Norman E.

1992-01-01

The suitability of using rain-flow reconstructions as an alternative to an original loading spectrum for component fatigue life testing is investigated. A modified helicopter maneuver history is used for the rain-flow cycle counting and history regenerations. Experimental testing on a notched test specimen over a wide range of loads produces similar lives for the original history and the reconstructions. The test lives also agree with a simplified local strain analysis performed on the specimen utilizing the rain-flow cycle count. The rain-flow reconstruction technique is shown to be a viable test spectrum alternative to storing the complete original load history, especially in saving computer storage space and processing time. A description of the regeneration method, the simplified life prediction analysis, and the experimental methods are included in the investigation.

Life cycle assessment modelling of waste-to-energy incineration in Spain and Portugal.

PubMed

Margallo, M; Aldaco, R; Irabien, A; Carrillo, V; Fischer, M; Bala, A; Fullana, P

2014-06-01

In recent years, waste management systems have been evaluated using a life cycle assessment (LCA) approach. A main shortcoming of prior studies was the focus on a mixture of waste with different characteristics. The estimation of emissions and consumptions associated with each waste fraction in these studies presented allocation problems. Waste-to-energy (WTE) incineration is a clear example in which municipal solid waste (MSW), comprising many types of materials, is processed to produce several outputs. This paper investigates an approach to better understand incineration processes in Spain and Portugal by applying a multi-input/output allocation model. The application of this model enabled predictions of WTE inputs and outputs, including the consumption of ancillary materials and combustibles, air emissions, solid wastes, and the energy produced during the combustion of each waste fraction. © The Author(s) 2014.

How life affects the geochemical cycle of carbon

NASA Technical Reports Server (NTRS)

Walker, James C. G.

1992-01-01

Developing a quantitative understanding of the biogeochemical cycles of carbon as they have worked throughout Earth history on various time scales, how they have been affected by biological evolution, and how changes in the carbon content of ocean and atmosphere may have affected climate and the evolution of life are the goals of the research. Theoretical simulations were developed that can be tuned to reproduce such data as exist and, once tuned, can be used to predict properties that have not yet been observed. This is an ongoing process, in which models and results are refined as new data and interpretations become available and as understanding of the global system improves. Results of the research are described in several papers which were published or submitted for publication. These papers are summarized. Future research plans are presented.

Application of Life Cycle Assessment on Electronic Waste Management: A Review.

PubMed

Xue, Mianqiang; Xu, Zhenming

2017-04-01

Electronic waste is a rich source of both valuable materials and toxic substances. Management of electronic waste is one of the biggest challenges of current worldwide concern. As an effective and prevailing environmental management tool, life cycle assessment can evaluate the environmental performance of electronic waste management activities. Quite a few scientific literatures reporting life cycle assessment of electronic waste management with significant outcomes have been recently published. This paper reviewed the trends, characteristics, research gaps, and challenges of these studies providing detailed information for practitioners involved in electronic waste management. The results showed that life cycle assessment studies were most carried out in Europe, followed by Asia and North America. The research subject of the studies mainly includes monitors, waste printed circuit boards, mobile phones, computers, printers, batteries, toys, dishwashers, and light-emitting diodes. CML was the most widely used life cycle impact assessment method in life cycle assessment studies on electronic waste management, followed by EI99. Furthermore, 40% of the reviewed studies combined with other environmental tools, including life cycle cost, material flow analysis, multi-criteria decision analysis, emergy analysis, and hazard assessment which came to more comprehensive conclusions from different aspects. The research gaps and challenges including uneven distribution of life cycle assessment studies, life cycle impact assessment methods selection, comparison of the results, and uncertainty of the life cycle assessment studies were examined. Although life cycle assessment of electronic waste management facing challenges, their results will play more and more important role in electronic waste management practices.

Application of Life Cycle Assessment on Electronic Waste Management: A Review

NASA Astrophysics Data System (ADS)

Xue, Mianqiang; Xu, Zhenming

2017-04-01

Electronic waste is a rich source of both valuable materials and toxic substances. Management of electronic waste is one of the biggest challenges of current worldwide concern. As an effective and prevailing environmental management tool, life cycle assessment can evaluate the environmental performance of electronic waste management activities. Quite a few scientific literatures reporting life cycle assessment of electronic waste management with significant outcomes have been recently published. This paper reviewed the trends, characteristics, research gaps, and challenges of these studies providing detailed information for practitioners involved in electronic waste management. The results showed that life cycle assessment studies were most carried out in Europe, followed by Asia and North America. The research subject of the studies mainly includes monitors, waste printed circuit boards, mobile phones, computers, printers, batteries, toys, dishwashers, and light-emitting diodes. CML was the most widely used life cycle impact assessment method in life cycle assessment studies on electronic waste management, followed by EI99. Furthermore, 40% of the reviewed studies combined with other environmental tools, including life cycle cost, material flow analysis, multi-criteria decision analysis, emergy analysis, and hazard assessment which came to more comprehensive conclusions from different aspects. The research gaps and challenges including uneven distribution of life cycle assessment studies, life cycle impact assessment methods selection, comparison of the results, and uncertainty of the life cycle assessment studies were examined. Although life cycle assessment of electronic waste management facing challenges, their results will play more and more important role in electronic waste management practices.

Coal mining and the resource community cycle: A longitudinal assessment of the social impacts of the Coppabella coal mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lockie, S.; Franettovich, M.; Petkova-Timmer, V.

Two social impact assessment (SIA) studies of Central Queensland's Coppabella coal mine were undertaken in 2002-2003 and 2006-2007. As ex post studies of actual change, these provide a reference point for predictive assessments of proposed resource extraction projects at other sites, while the longitudinal element added by the second study illustrates how impacts associated with one mine may vary over time due to changing economic and social conditions. It was found that the traditional coupling of local economic vitality and community development to the life cycle of resource projects - the resource community cycle - was mediated by labour recruitmentmore » and social infrastructure policies that reduced the emphasis on localised employment and investment strategies. and by the cumulative impacts of multiple mining projects within relative proximity to each other. The resource community cycle was accelerated and local communities forced to consider ways of attracting secondary investment and/or alternative industries early in the operational life of the Coppabella mine in order to secure significant economic benefits and to guard against the erosion of social capital and the ability to cope with future downturns in the mining sector.« less

Improved Predictions of the Geographic Distribution of Invasive Plants Using Climatic Niche Models.

PubMed

Ramírez-Albores, Jorge E; Bustamante, Ramiro O; Badano, Ernesto I

2016-01-01

Climatic niche models for invasive plants are usually constructed with occurrence records taken from literature and collections. Because these data neither discriminate among life-cycle stages of plants (adult or juvenile) nor the origin of individuals (naturally established or man-planted), the resulting models may mispredict the distribution ranges of these species. We propose that more accurate predictions could be obtained by modelling climatic niches with data of naturally established individuals, particularly with occurrence records of juvenile plants because this would restrict the predictions of models to those sites where climatic conditions allow the recruitment of the species. To test this proposal, we focused on the Peruvian peppertree (Schinus molle), a South American species that has largely invaded Mexico. Three climatic niche models were constructed for this species using high-resolution dataset gathered in the field. The first model included all occurrence records, irrespective of the life-cycle stage or origin of peppertrees (generalized niche model). The second model only included occurrence records of naturally established mature individuals (adult niche model), while the third model was constructed with occurrence records of naturally established juvenile plants (regeneration niche model). When models were compared, the generalized climatic niche model predicted the presence of peppertrees in sites located farther beyond the climatic thresholds that naturally established individuals can tolerate, suggesting that human activities influence the distribution of this invasive species. The adult and regeneration climatic niche models concurred in their predictions about the distribution of peppertrees, suggesting that naturally established adult trees only occur in sites where climatic conditions allow the recruitment of juvenile stages. These results support the proposal that climatic niches of invasive plants should be modelled with data of naturally established individuals because this improves the accuracy of predictions about their distribution ranges.

Improved Predictions of the Geographic Distribution of Invasive Plants Using Climatic Niche Models

PubMed Central

Ramírez-Albores, Jorge E.; Bustamante, Ramiro O.

2016-01-01

Climatic niche models for invasive plants are usually constructed with occurrence records taken from literature and collections. Because these data neither discriminate among life-cycle stages of plants (adult or juvenile) nor the origin of individuals (naturally established or man-planted), the resulting models may mispredict the distribution ranges of these species. We propose that more accurate predictions could be obtained by modelling climatic niches with data of naturally established individuals, particularly with occurrence records of juvenile plants because this would restrict the predictions of models to those sites where climatic conditions allow the recruitment of the species. To test this proposal, we focused on the Peruvian peppertree (Schinus molle), a South American species that has largely invaded Mexico. Three climatic niche models were constructed for this species using high-resolution dataset gathered in the field. The first model included all occurrence records, irrespective of the life-cycle stage or origin of peppertrees (generalized niche model). The second model only included occurrence records of naturally established mature individuals (adult niche model), while the third model was constructed with occurrence records of naturally established juvenile plants (regeneration niche model). When models were compared, the generalized climatic niche model predicted the presence of peppertrees in sites located farther beyond the climatic thresholds that naturally established individuals can tolerate, suggesting that human activities influence the distribution of this invasive species. The adult and regeneration climatic niche models concurred in their predictions about the distribution of peppertrees, suggesting that naturally established adult trees only occur in sites where climatic conditions allow the recruitment of juvenile stages. These results support the proposal that climatic niches of invasive plants should be modelled with data of naturally established individuals because this improves the accuracy of predictions about their distribution ranges. PMID:27195983

Transportation life cycle assessment (LCA) synthesis : life cycle assessment learning module series.

DOT National Transportation Integrated Search

2015-03-12

The Life Cycle Assessment Learning Module Series is a set of narrated, self-advancing slideshows on : various topics related to environmental life cycle assessment (LCA). This research project produced the first 27 of such modules, which : are freely...

Cost analysis of life support systems

NASA Technical Reports Server (NTRS)

Yakut, M. M.

1973-01-01

A methodology was developed to predict realistic relative cost of Life Support Systems (LSS) and to define areas of major cost impacts in the development cycle. Emphasis was given to tailoring the cost data for usage by program planners and designers. The equipment classifications used based on the degree of refinement were as follows: (1) Working model; (2) low-fidelity prototype; (3) high-fidelity prototype; and (4) flight-qualified system. The major advanced LSS evaluated included the following: (1) Carbon dioxide removal; (2) oxygen recovery systems; (3) water recovery systems; (4) atmosphere analysis system.

The reliability-quality relationship for quality systems and quality risk management.

PubMed

Claycamp, H Gregg; Rahaman, Faiad; Urban, Jason M

2012-01-01

Engineering reliability typically refers to the probability that a system, or any of its components, will perform a required function for a stated period of time and under specified operating conditions. As such, reliability is inextricably linked with time-dependent quality concepts, such as maintaining a state of control and predicting the chances of losses from failures for quality risk management. Two popular current good manufacturing practice (cGMP) and quality risk management tools, failure mode and effects analysis (FMEA) and root cause analysis (RCA) are examples of engineering reliability evaluations that link reliability with quality and risk. Current concepts in pharmaceutical quality and quality management systems call for more predictive systems for maintaining quality; yet, the current pharmaceutical manufacturing literature and guidelines are curiously silent on engineering quality. This commentary discusses the meaning of engineering reliability while linking the concept to quality systems and quality risk management. The essay also discusses the difference between engineering reliability and statistical (assay) reliability. The assurance of quality in a pharmaceutical product is no longer measured only "after the fact" of manufacturing. Rather, concepts of quality systems and quality risk management call for designing quality assurance into all stages of the pharmaceutical product life cycle. Interestingly, most assays for quality are essentially static and inform product quality over the life cycle only by being repeated over time. Engineering process reliability is the fundamental concept that is meant to anticipate quality failures over the life cycle of the product. Reliability is a well-developed theory and practice for other types of manufactured products and manufacturing processes. Thus, it is well known to be an appropriate index of manufactured product quality. This essay discusses the meaning of reliability and its linkages with quality systems and quality risk management.

Virulence strategies for infecting phagocytes deduced from the in vivo transcriptional program of Legionella pneumophila.

PubMed

Brüggemann, Holger; Hagman, Arne; Jules, Matthieu; Sismeiro, Odile; Dillies, Marie-Agnès; Gouyette, Catherine; Kunst, Frank; Steinert, Michael; Heuner, Klaus; Coppée, Jean-Yves; Buchrieser, Carmen

2006-08-01

Adaptation to the host environment and exploitation of host cell functions are critical to the success of intracellular pathogens. Here, insight to these virulence mechanisms was obtained for the first time from the transcriptional program of the human pathogen Legionella pneumophila during infection of its natural host, Acanthamoeba castellanii. The biphasic life cycle of L. pneumophila was reflected by a major shift in gene expression from replicative to transmissive phase, concerning nearly half of the genes predicted in the genome. However, three different L. pneumophila strains showed similar in vivo gene expression patterns, indicating that common regulatory mechanisms govern the Legionella life cycle, despite the plasticity of its genome. During the replicative phase, in addition to components of aerobic metabolism and amino acid catabolism, the Entner-Doudoroff pathway, a NADPH producing mechanism used for sugar and/or gluconate assimilation, was expressed, suggesting for the first time that intracellular L. pneumophila may also scavenge host carbohydrates as nutrients and not only proteins. Identification of genes only upregulated in vivo but not in vitro, may explain higher virulence of in vivo grown L. pneumophila. Late in the life cycle, L. pneumophila upregulates genes predicted to promote transmission and manipulation of a new host cell, therewith priming it for the next attack. These including substrates of the Dot/Icm secretion system, other factors associated previously with invasion and virulence, the motility and the type IV pilus machineries, and > 90 proteins not characterized so far. Analysis of a fliA (sigma28) deletion mutant identified genes coregulated with the flagellar regulon, including GGDEF/EAL regulators and factors that promote host cell entry and survival.

Fatigue life analysis for traction drives with application to a toroidal type geometry

NASA Technical Reports Server (NTRS)

Coy, J. J.; Loewenthal, S. H.; Zaretsky, E. V.

1976-01-01

A contact fatigue life analysis for traction drives was developed which was based on a modified Lundberg-Palmgren theory. The analysis was used to predict life for a cone-roller toroidal traction drive. A 90-percent probability of survival was assumed for the calculated life. Parametric results were presented for life and Hertz contact stress as a function of load, drive ratio, and size. A design study was also performed. The results were compared to previously published work for the dual cavity toroidal drive as applied to a typical compact passenger vehicle drive train. For a representative duty cycle condition wherein the engine delivers 29 horsepower at 2000 rpm with the vehicle moving at 48.3 km/hr (30 mph) the drive life was calculated to be 19,200 km (11 900 miles).

Comparison of two common aEEG classifications for the prediction of neurodevelopmental outcome in preterm infants.

PubMed

Bruns, Nora; Dransfeld, Frauke; Hüning, Britta; Hobrecht, Julia; Storbeck, Tobias; Weiss, Christel; Felderhoff-Müser, Ursula; Müller, Hanna

2017-02-01

Neurodevelopmental outcome after prematurity is crucial. The aim was to compare two amplitude-integrated EEG (aEEG) classifications (Hellström-Westas (HW), Burdjalov) for outcome prediction. We recruited 65 infants ≤32 weeks gestational age with aEEG recordings within the first 72 h of life and Bayley testing at 24 months corrected age or death. Statistical analyses were performed for each 24 h section to determine whether very immature/depressed or mature/developed patterns predict survival/neurological outcome and to find predictors for mental development index (MDI) and psychomotor development index (PDI) at 24 months corrected age. On day 2, deceased infants showed no cycling in 80% (HW, p = 0.0140) and 100% (Burdjalov, p = 0.0041). The Burdjalov total score significantly differed between groups on day 2 (p = 0.0284) and the adapted Burdjalov total score on day 2 (p = 0.0183) and day 3 (p = 0.0472). Cycling on day 3 (HW; p = 0.0059) and background on day 3 (HW; p = 0.0212) are independent predictors for MDI (p = 0.0016) whereas no independent predictor for PDI was found (multiple regression analyses). Cycling in both classifications is a valuable tool to assess chance of survival. The classification by HW is also associated with long-term mental outcome. What is Known: •Neurodevelopmental outcome after preterm birth remains one of the major concerns in neonatology. •aEEG is used to measure brain activity and brain maturation in preterm infants. What is New: •The two common aEEG classifications and scoring systems described by Hellström-Westas and Burdjalov are valuable tools to predict neurodevelopmental outcome when performed within the first 72 h of life. •Both aEEG classifications are useful to predict chance of survival. The classification by Hellström-Westas can also predict long-term outcome at corrected age of 2 years.

LIFE CYCLE DESIGN FRAMEWORK AND DEMONSTRATION PROJECTS PROFILES OF AT&T AND ALLIED SIGNAL

EPA Science Inventory

Life cycle design seeks to minimize the environmental burden associated with a product life cycle from raw materials acquisition through manufacturing, use, and end-of-life management. ife cycle design emphasizes integrating environmental requirements into the earliest phases of ...

Stochastic variation in avian survival rates: Life-history predictions, population consequences, and the potential responses to human perturbations and climate change

USGS Publications Warehouse

Schmutz, Joel A.; Thomson, David L.; Cooch, Evan G.; Conroy, Michael J.

2009-01-01

Stochastic variation in survival rates is expected to decrease long-term population growth rates. This expectation influences both life-history theory and the conservation of species. From this expectation, Pfister (1998) developed the important life-history prediction that natural selection will have minimized variability in those elements of the annual life cycle (such as adult survival rate) with high sensitivity. This prediction has not been rigorously evaluated for bird populations, in part due to statistical difficulties related to variance estimation. I here overcome these difficulties, and in an analysis of 62 populations, I confirm her prediction by showing a negative relationship between the proportional sensitivity (elasticity) of adult survival and the proportional variance (CV) of adult survival. However, several species deviated significantly from this expectation, with more process variance in survival than predicted. For instance, projecting the magnitude of process variance in annual survival for American redstarts (Setophaga ruticilla) for 25 years resulted in a 44% decline in abundance without assuming any change in mean survival rate. For most of these species with high process variance, recent changes in harvest, habitats, or changes in climate patterns are the likely sources of environmental variability causing this variability in survival. Because of climate change, environmental variability is increasing on regional and global scales, which is expected to increase stochasticity in vital rates of species. Increased stochasticity in survival will depress population growth rates, and this result will magnify the conservation challenges we face.

Numerical fatigue analysis of premolars restored by CAD/CAM ceramic crowns.

PubMed

Homaei, Ehsan; Jin, Xiao-Zhuang; Pow, Edmond Ho Nang; Matinlinna, Jukka Pekka; Tsoi, James Kit-Hon; Farhangdoost, Khalil

2018-04-10

The purpose of this study was to estimate the fatigue life of premolars restored with two dental ceramics, lithium disilicate (LD) and polymer infiltrated ceramic (PIC) using the numerical method and compare it with the published in vitro data. A premolar restored with full-coverage crown was digitized. The volumetric shape of tooth tissues and crowns were created in Mimics ® . They were transferred to IA-FEMesh for mesh generation and the model was analyzed with Abaqus. By combining the stress distribution results with fatigue stress-life (S-N) approach, the lifetime of restored premolars was predicted. The predicted lifetime was 1,231,318 cycles for LD with fatigue load of 1400N, while the one for PIC was 475,063 cycles with the load of 870N. The peak value of maximum principal stress occurred at the contact area (LD: 172MPa and PIC: 96MPa) and central fossa (LD: 100MPa and PIC: 64MPa) for both ceramics which were the most seen failure areas in the experiment. In the adhesive layer, the maximum shear stress was observed at the shoulder area (LD: 53.6MPa and PIC: 29MPa). The fatigue life and failure modes of all-ceramic crown determined by the numerical method seem to correlate well with the previous experimental study. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Life cycles of dominant mayflies (Ephemeroptera) on a torrent of the high Bolivian Andes

PubMed

Molina, Carlos I; Puliafico, Kenneth P

2016-03-01

The mayflies of the temperate and cold zones have well-synchronized life cycles, distinct cohorts, short emergence and flight periods. In contrast, aquatic insects from the tropical zones are characterized by multivoltine life cycles, “non-discernible cohorts” and extended flight periods throughout the year. This report is the first observation of life cycle patterns made of two species of mayflies on a torrent in the high elevation Bolivian Andes. The samples were taken from four sites and four periods during a hydrological season. The life cycle of each species was examined using size-class frequency analysis and a monthly modal progression model (von Bertalanffy’s model) to infer the life cycle synchrony type. These first observations showed a moderately synchronized univoltine life cycle for Andesiops peruvianus (Ulmer, 1920), whereas Meridialaris tintinnabula Pescador and Peters (1987), had an unsynchronized multivoltine life cycle. These results showed that the generalization of all aquatic insects as unsynchronized multivoltine species in the Andean region may not be entirely accurate since there is still a need to further clarify the life cycle patterns of the wide variety of aquatic insects living in this high elevation tropical environment.

From Centralized Disassembly to Life Cycle Management: Status and Progress of E-waste Treatment System in China

NASA Astrophysics Data System (ADS)

Song, Xiaolong; Yang, Jianxin; Lu, Bin; Yang, Dong

2017-01-01

China is now facing e-waste problems from both growing domestic generation and illegal imports. Many stakeholders are involved in the e-waste treatment system due to the complexity of e-waste life cycle. Beginning with the state of the e-waste treatment industry in China, this paper summarizes the latest progress in e-waste management from such aspects as the new edition of the China RoHS Directive, new Treatment List, new funding subsidy standard, and eco-design pilots. Thus, a conceptual model for life cycle management of e-waste is generalized. The operating procedure is to first identify the life cycle stages of the e-waste and extract the important life cycle information. Then, life cycle tools can be used to conduct a systematic analysis to help decide how to maximize the benefits from a series of life cycle engineering processes. Meanwhile, life cycle thinking is applied to improve the legislation relating to e-waste so as to continuously improve the sustainability of the e-waste treatment system. By providing an integrative framework, the life cycle management of e-waste should help to realize sustainable management of e-waste in developing countries.

Optimizing product life cycle processes in design phase

NASA Astrophysics Data System (ADS)

Faneye, Ola. B.; Anderl, Reiner

2002-02-01

Life cycle concepts do not only serve as basis in assisting product developers understand the dependencies between products and their life cycles, they also help in identifying potential opportunities for improvement in products. Common traditional concepts focus mainly on energy and material flow across life phases, necessitating the availability of metrics derived from a reference product. Knowledge of life cycle processes won from an existing product is directly reused in its redesign. Depending on sales volume nevertheless, the environmental impact before product optimization can be substantial. With modern information technologies today, computer-aided life cycle methodologies can be applied well before product use. On the basis of a virtual prototype, life cycle processes are analyzed and optimized, using simulation techniques. This preventive approach does not only help in minimizing (or even eliminating) environmental burdens caused by product, costs incurred due to changes in real product can also be avoided. The paper highlights the relationship between product and life cycle and presents a computer-based methodology for optimizing the product life cycle during design, as presented by SFB 392: Design for Environment - Methods and Tools at Technical University, Darmstadt.

LCIA framework and cross-cutting issues guidance within the UNEP/SETAC Life Cycle Initiative

EPA Science Inventory

Increasing needs for decision support and advances in scientific knowledge within life cycle assessment (LCA) led to substantial efforts to provide global guidance on environmental life cycle impact assessment (LCIA) indicators under the auspices of the UNEP-SETAC Life Cycle Init...

Predicting the 3D fatigue crack growth rate of small cracks using multimodal data via Bayesian networks: In-situ experiments and crystal plasticity simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rovinelli, Andrea; Sangid, Michael D.; Proudhon, Henry

Small crack propagation accounts for most of the fatigue life of engineering structures subject to high cycle fatigue loading conditions. Determining the fatigue crack growth rate of small cracks propagating into polycrystalline engineering alloys is critical to improving fatigue life predictions, thus lowering cost and increasing safety. In this work, cycle-by-cycle data of a small crack propagating in a beta metastable titanium alloy is available via phase and diffraction contrast tomography. Crystal plasticity simulations are used to supplement experimental data regarding the micromechanical fields ahead of the crack tip. Experimental and numerical results are combined into a multimodal dataset andmore » sampled utilizing a non-local data mining procedure. Furthermore, to capture the propensity of body-centered cubic metals to deform according to the pencil-glide model, a non-local driving force is postulated. The proposed driving force serves as the basis to construct a data-driven probabilistic crack propagation framework using Bayesian networks as building blocks. The spatial correlation between the postulated driving force and experimental observations is obtained by analyzing the results of the proposed framework. Results show that the above correlation increases proportionally to the distance from the crack front until the edge of the plastic zone. Moreover, the predictions of the propagation framework show good agreement with experimental observations. Finally, we studied the interaction of a small crack with grain boundaries (GBs) utilizing various slip transmission criteria, revealing the tendency of a crack to cross a GB by propagating along the slip directions minimizing the residual Burgers vector within the GB.« less

Predicting the 3D fatigue crack growth rate of small cracks using multimodal data via Bayesian networks: In-situ experiments and crystal plasticity simulations

NASA Astrophysics Data System (ADS)

Rovinelli, Andrea; Sangid, Michael D.; Proudhon, Henry; Guilhem, Yoann; Lebensohn, Ricardo A.; Ludwig, Wolfgang

2018-06-01

Small crack propagation accounts for most of the fatigue life of engineering structures subject to high cycle fatigue loading conditions. Determining the fatigue crack growth rate of small cracks propagating into polycrystalline engineering alloys is critical to improving fatigue life predictions, thus lowering cost and increasing safety. In this work, cycle-by-cycle data of a small crack propagating in a beta metastable titanium alloy is available via phase and diffraction contrast tomography. Crystal plasticity simulations are used to supplement experimental data regarding the micromechanical fields ahead of the crack tip. Experimental and numerical results are combined into a multimodal dataset and sampled utilizing a non-local data mining procedure. Furthermore, to capture the propensity of body-centered cubic metals to deform according to the pencil-glide model, a non-local driving force is postulated. The proposed driving force serves as the basis to construct a data-driven probabilistic crack propagation framework using Bayesian networks as building blocks. The spatial correlation between the postulated driving force and experimental observations is obtained by analyzing the results of the proposed framework. Results show that the above correlation increases proportionally to the distance from the crack front until the edge of the plastic zone. Moreover, the predictions of the propagation framework show good agreement with experimental observations. Finally, we studied the interaction of a small crack with grain boundaries (GBs) utilizing various slip transmission criteria, revealing the tendency of a crack to cross a GB by propagating along the slip directions minimizing the residual Burgers vector within the GB.

Predicting the 3D fatigue crack growth rate of small cracks using multimodal data via Bayesian networks: In-situ experiments and crystal plasticity simulations

DOE PAGES

Rovinelli, Andrea; Sangid, Michael D.; Proudhon, Henry; ...

2018-03-11

Small crack propagation accounts for most of the fatigue life of engineering structures subject to high cycle fatigue loading conditions. Determining the fatigue crack growth rate of small cracks propagating into polycrystalline engineering alloys is critical to improving fatigue life predictions, thus lowering cost and increasing safety. In this work, cycle-by-cycle data of a small crack propagating in a beta metastable titanium alloy is available via phase and diffraction contrast tomography. Crystal plasticity simulations are used to supplement experimental data regarding the micromechanical fields ahead of the crack tip. Experimental and numerical results are combined into a multimodal dataset andmore » sampled utilizing a non-local data mining procedure. Furthermore, to capture the propensity of body-centered cubic metals to deform according to the pencil-glide model, a non-local driving force is postulated. The proposed driving force serves as the basis to construct a data-driven probabilistic crack propagation framework using Bayesian networks as building blocks. The spatial correlation between the postulated driving force and experimental observations is obtained by analyzing the results of the proposed framework. Results show that the above correlation increases proportionally to the distance from the crack front until the edge of the plastic zone. Moreover, the predictions of the propagation framework show good agreement with experimental observations. Finally, we studied the interaction of a small crack with grain boundaries (GBs) utilizing various slip transmission criteria, revealing the tendency of a crack to cross a GB by propagating along the slip directions minimizing the residual Burgers vector within the GB.« less

The Model Life-cycle: Training Module

EPA Pesticide Factsheets

Model Life-Cycle includes identification of problems & the subsequent development, evaluation, & application of the model. Objectives: define ‘model life-cycle’, explore stages of model life-cycle, & strategies for development, evaluation, & applications.

10 CFR 434.607 - Life cycle cost analysis criteria.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 3 2011-01-01 2011-01-01 false Life cycle cost analysis criteria. 434.607 Section 434.607... HIGH RISE RESIDENTIAL BUILDINGS Building Energy Compliance Alternative § 434.607 Life cycle cost analysis criteria. 607.1 The following life cycle cost criteria applies to the fuel selection requirements...

77 FR 38766 - Proposed Information Collection; Comment Request; International Client Life-Cycle Multi-Purpose...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-29

... Request; International Client Life-Cycle Multi-Purpose Forms AGENCY: International Trade Administration... aspects of an international organization's life-cycle with CS. CS is mandated by Congress to help U.S... trade events to U.S. organizations. The International Client Life-cycle Multi-Purpose Forms, previously...

10 CFR 435.8 - Life-cycle costing.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 3 2011-01-01 2011-01-01 false Life-cycle costing. 435.8 Section 435.8 Energy DEPARTMENT... BUILDINGS Mandatory Energy Efficiency Standards for Federal Low-Rise Residential Buildings. § 435.8 Life-cycle costing. Each Federal agency shall determine life-cycle cost-effectiveness by using the procedures...

77 FR 38582 - Proposed Information Collection; Comment Request; Domestic Client Life-Cycle Multi-Purpose Forms

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-28

... Request; Domestic Client Life-Cycle Multi-Purpose Forms AGENCY: International Trade Administration. ACTION... life-cycle with CS. CS is mandated by Congress to help U.S. organizations, particularly small and... Client Life-cycle Multi-Purpose Forms, previously titled Export Information Services Order Forms, are...

10 CFR 434.607 - Life cycle cost analysis criteria.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Life cycle cost analysis criteria. 434.607 Section 434.607... HIGH RISE RESIDENTIAL BUILDINGS Building Energy Compliance Alternative § 434.607 Life cycle cost analysis criteria. 607.1 The following life cycle cost criteria applies to the fuel selection requirements...

10 CFR 435.8 - Life-cycle costing.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Life-cycle costing. 435.8 Section 435.8 Energy DEPARTMENT... BUILDINGS Mandatory Energy Efficiency Standards for Federal Low-Rise Residential Buildings. § 435.8 Life-cycle costing. Each Federal agency shall determine life-cycle cost-effectiveness by using the procedures...

US Federal LCA Commons Life Cycle Inventory Unit Process Template

EPA Science Inventory

The US Federal LCA Commons Life Cycle Inventory Unit Process Template is a multi-sheet Excel template for life cycle inventory data, metadata and other documentation. The template comes as a package that consistent of three parts: (1) the main template itself for life cycle inven...

76 FR 41525 - Hewlett Packard Global Parts Supply Chain, Global Product Life Cycles Management Unit Including...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-14

... Parts Supply Chain, Global Product Life Cycles Management Unit Including Teleworkers Reporting to... workers of Hewlett Packard, Global Parts Supply Chain, Global Product Life Cycles Management Unit...). Since eligible workers of Hewlett Packard, Global Parts Supply Chain, Global Product Life Cycles...

7 CFR 2902.8 - Determining life cycle costs, environmental and health benefits, and performance.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 15 2010-01-01 2010-01-01 false Determining life cycle costs, environmental and... DESIGNATING BIOBASED PRODUCTS FOR FEDERAL PROCUREMENT General § 2902.8 Determining life cycle costs, environmental and health benefits, and performance. (a) Providing information on life cycle costs and...

77 FR 50724 - Developing Software Life Cycle Processes for Digital Computer Software Used in Safety Systems of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-22

... NUCLEAR REGULATORY COMMISSION [NRC-2012-0195] Developing Software Life Cycle Processes for Digital... Software Life Cycle Processes for Digital Computer Software used in Safety Systems of Nuclear Power Plants... clarifications, the enhanced consensus practices for developing software life-cycle processes for digital...

Center-iodized graphene as an advanced anode material to significantly boost the performance of lithium-ion batteries.

PubMed

Chen, Jie; Xu, Mao-Wen; Wu, Jinggao; Li, Chang Ming

2018-05-17

Iodine edge-doped graphene can improve the capacity and stability of lithium-ion batteries (LIBs). Our theoretical calculations indicate that center-iodization can further significantly enhance the anode catalytic process. To experimentally prove the theoretical prediction, iodine-doped graphene materials were prepared by one-pot hydrothermal and ball-milling approaches to realize different doping-sites. Results show that the center-iodinated graphene (CIG) anode exhibits a remarkably high reversible capacity (1121 mA h g-1 after 180 cycles at 0.5 A g-1), long-cycle life (0.01% decay per cycle over 300 cycles at 1 A g-1) and high-rate capacity (374 mA h g-1 after 800 cycles at 8 A g-1), which greatly improves the performance of the edge-iodinated graphene anode and these results are in good agreement with the theoretical analysis. More importantly, the CIG anode also delivers a high-rate capacity and excellent cycling stability (279 mA h g-1 after 500 cycles at 10 A g-1) in full-cells. Both the theoretical analysis and experimental investigation reveal the enhancement mechanism, in which the center-iodization increases the surface charge for fast electron transfer rate, improves the conductivity for charge transport and rationalizes the pore structure for enhanced mass transport and ion insertion/desertion, thus resulting in a high rate capacity and long cycle life. This work not only discloses the critical role of catalytic sites including both amounts and site positions but also offers great potential for high-power rechargeable LIB applications.

The role of microstructure and phase distribution in the failure mechanisms and life prediction model for PSZ coatings

NASA Technical Reports Server (NTRS)

Sisson, R. D., Jr.; Sone, Ichiro; Biederman, R. R.

1985-01-01

Partially Stabilized Zirconia (PSZ) may become widely used for Thermal Barrier Coatings (TBC). Failure of these coatings can occur due to thermal fatigue in oxidizing atmospheres. The failure is due to the strains that develop due to thermal gradients, differences in thermal expansion coefficients, and oxidation of the bond coating. The role of microstructure and the cubic, tetragonal, and monoclinic phase distribution in the strain development and subsequent failure will be discussed. An X-ray diffraction technique for accurate determination of the fraction of each phase in PSZ will be applied to understanding the phase transformations and strain development. These results will be discussed in terms of developing a model for life prediction in PSZ coatings during thermal cycling.

Life cycle replacement by gene introduction under an allee effect in periodical cicadas.

PubMed

Nariai, Yukiko; Hayashi, Saki; Morita, Satoru; Umemura, Yoshitaka; Tainaka, Kei-ichi; Sota, Teiji; Cooley, John R; Yoshimura, Jin

2011-04-06

Periodical cicadas (Magicicada spp.) in the USA are divided into three species groups (-decim, -cassini, -decula) of similar but distinct morphology and behavior. Each group contains at least one species with a 17-year life cycle and one with a 13-year cycle; each species is most closely related to one with the other cycle. One explanation for the apparent polyphyly of 13- and 17-year life cycles is that populations switch between the two cycles. Using a numerical model, we test the general feasibility of life cycle switching by the introduction of alleles for one cycle into populations of the other cycle. Our results suggest that fitness reductions at low population densities of mating individuals (the Allee effect) could play a role in life cycle switching. In our model, if the 13-year cycle is genetically dominant, a 17-year cycle population will switch to a 13-year cycle given the introduction of a few 13-year cycle alleles under a moderate Allee effect. We also show that under a weak Allee effect, different year-classes ("broods") with 17-year life cycles can be generated. Remarkably, the outcomes of our models depend only on the dominance relationships of the cycle alleles, irrespective of any fitness advantages.

Analysis of thermal mechanical fatigue in titanium matrix composites

NASA Technical Reports Server (NTRS)

Johnson, W. Steven; Mirdamadi, Massoud

1993-01-01

Titanium metal matrix composites are being evaluated for structural applications on advanced hypersonic vehicles. These composites are reinforced with ceramic fibers such as silicon carbide, SCS-6. This combination of matrix and fiber results in a high stiffness, high strength composite that has good retention of properties even at elevated temperatures. However, significant thermal stresses are developed within the composite between the fiber and the matrix due to the difference in their respective coefficients of thermal expansion. In addition to the internal stresses that are generated due to thermal cycling, the overall laminate will be subjected to considerable mechanical loads during the thermal cycling. In order to develop life prediction methodology, one must be able to predict the stresses and strains that occur in the composite's constituents during the complex loading. Thus the purpose is to describe such an analytical tool, VISCOPLY.

Improved Environmental Life Cycle Assessment of Crop Production at the Catchment Scale via a Process-Based Nitrogen Simulation Model.

PubMed

Liao, Wenjie; van der Werf, Hayo M G; Salmon-Monviola, Jordy

2015-09-15

One of the major challenges in environmental life cycle assessment (LCA) of crop production is the nonlinearity between nitrogen (N) fertilizer inputs and on-site N emissions resulting from complex biogeochemical processes. A few studies have addressed this nonlinearity by combining process-based N simulation models with LCA, but none accounted for nitrate (NO3(-)) flows across fields. In this study, we present a new method, TNT2-LCA, that couples the topography-based simulation of nitrogen transfer and transformation (TNT2) model with LCA, and compare the new method with a current LCA method based on a French life cycle inventory database. Application of the two methods to a case study of crop production in a catchment in France showed that, compared to the current method, TNT2-LCA allows delineation of more appropriate temporal limits when developing data for on-site N emissions associated with specific crops in this catchment. It also improves estimates of NO3(-) emissions by better consideration of agricultural practices, soil-climatic conditions, and spatial interactions of NO3(-) flows across fields, and by providing predicted crop yield. The new method presented in this study provides improved LCA of crop production at the catchment scale.

Dynamic energy budget as a basis to model population-level effects of zinc-spiked sediments in the gastropod Valvata piscinalis.

PubMed

Ducrot, Virginie; Péry, Alexandre R R; Mons, Raphaël; Quéau, Hervé; Charles, Sandrine; Garric, Jeanne

2007-08-01

This paper presents original toxicity test designs and mathematical models that may be used to assess the deleterious effects of toxicants on Valvata piscinalis (Mollusca, Gastropoda). Results obtained for zinc, used as a reference toxicant, are presented. The feeding behavior, juvenile survival, growth, age at puberty, onset of reproduction, number of breedings during the life cycle, and fecundity were significantly altered when the snails were exposed to zinc-spiked sediments. Dynamic energy budget models (DEBtox) adequately predicted the effects of zinc on the V. piscinalis life cycle. They also provided estimates for lifecycle parameters that were used to parameterize a demographic model, based on a Z-transformed life-cycle graph. The effect threshold for the population growth rate (lambda) was estimated at 259 mg/kg dry sediment of zinc, showing that significant changes in abundance may occur at environmental concentrations. Significant effects occurring just above this threshold value were mainly caused by the severe impairment of reproductive endpoints. Sensitivity analysis showed that the value of lambda depended mainly on the juvenile survival rate. The impairment of this latter parameter may result in extinction of V. piscinalis. Finally, the present study highlights advantages of the proposed modeling approach in V. piscinalis and possible transfer to other test species and contaminants.

Estimation of fatigue life using electromechanical impedance technique

NASA Astrophysics Data System (ADS)

Lim, Yee Yan; Soh, Chee Kiong

2010-04-01

Fatigue induced damage is often progressive and gradual in nature. Structures subjected to large number of fatigue load cycles will encounter the process of progressive crack initiation, propagation and finally fracture. Monitoring of structural health, especially for the critical components, is therefore essential for early detection of potential harmful crack. Recent advent of smart materials such as piezo-impedance transducer adopting the electromechanical impedance (EMI) technique and wave propagation technique are well proven to be effective in incipient damage detection and characterization. Exceptional advantages such as autonomous, real-time and online, remote monitoring may provide a cost-effective alternative to the conventional structural health monitoring (SHM) techniques. In this study, the main focus is to investigate the feasibility of characterizing a propagating fatigue crack in a structure using the EMI technique as well as estimating its remaining fatigue life using the linear elastic fracture mechanics (LEFM) approach. Uniaxial cyclic tensile load is applied on a lab-sized aluminum beam up to failure. Progressive shift in admittance signatures measured by the piezo-impedance transducer (PZT patch) corresponding to increase of loading cycles reflects effectiveness of the EMI technique in tracing the process of fatigue damage progression. With the use of LEFM, prediction of the remaining life of the structure at different cycles of loading is possible.

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells. An update

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells - An update

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

The Analysis, Numerical Simulation, and Diagnosis of Extratropical Weather Systems

DTIC Science & Technology

1999-09-30

The Analysis, Numerical Simulation, and Diagnosis of Extratropical Weather Systems Dr. Melvyn A. Shapiro NOAA/Environmental Technology Laboratory...formulation, and numerical prediction of the life cycles of synoptic-scale and mesoscale extratropical weather systems, including the influence of planetary...scale inter-annual and intra-seasonal variability on their evolution. These weather systems include: extratropical oceanic and land-falling cyclones

Spatial ecological processes and local factors predict the distribution and abundance of spawning by steelhead (Oncorhynchus mykiss) across a complex riverscape

Treesearch

Jeffrey A. Falke; Jason B. Dunham; Christopher E. Jordan; Kristina M. McNyset; Gordon H. Reeves

2013-01-01

Processes that influence habitat selection in landscapes involve the interaction of habitat composition and configuration and are particularly important for species with complex life cycles. We assessed the relative influence of landscape spatial processes and local habitat characteristics on patterns in the distribution and abundance of spawning steelhead (...

Genome-to-Watershed Predictive Understanding of Terrestrial Environments

NASA Astrophysics Data System (ADS)

Hubbard, S. S.; Agarwal, D.; Banfield, J. F.; Beller, H. R.; Brodie, E.; Long, P.; Nico, P. S.; Steefel, C. I.; Tokunaga, T. K.; Williams, K. H.

2014-12-01

Although terrestrial environments play a critical role in cycling water, greenhouse gasses, and other life-critical elements, the complexity of interactions among component microbes, plants, minerals, migrating fluids and dissolved constituents hinders predictive understanding of system behavior. The 'Sustainable Systems 2.0' project is developing genome-to-watershed scale predictive capabilities to quantify how the microbiome affects biogeochemical watershed functioning, how watershed-scale hydro-biogeochemical processes affect microbial functioning, and how these interactions co-evolve with climate and land-use changes. Development of such predictive capabilities is critical for guiding the optimal management of water resources, contaminant remediation, carbon stabilization, and agricultural sustainability - now and with global change. Initial investigations are focused on floodplains in the Colorado River Basin, and include iterative model development, experiments and observations with an early emphasis on subsurface aspects. Field experiments include local-scale experiments at Rifle CO to quantify spatiotemporal metabolic and geochemical responses to O2and nitrate amendments as well as floodplain-scale monitoring to quantify genomic and biogeochemical response to natural hydrological perturbations. Information obtained from such experiments are represented within GEWaSC, a Genome-Enabled Watershed Simulation Capability, which is being developed to allow mechanistic interrogation of how genomic information stored in a subsurface microbiome affects biogeochemical cycling. This presentation will describe the genome-to-watershed scale approach as well as early highlights associated with the project. Highlights include: first insights into the diversity of the subsurface microbiome and metabolic roles of organisms involved in subsurface nitrogen, sulfur and hydrogen and carbon cycling; the extreme variability of subsurface DOC and hydrological controls on carbon and nitrogen cycling; geophysical identification of floodplain hotspots that are useful for model parameterization; and GEWaSC demonstration of how incorporation of identified microbial metabolic processes improves prediction of the larger system biogeochemical behavior.

Calibration Variability of 15 High Use Life Fitness Cycle Ergometers

DTIC Science & Technology

2013-12-02

minutes Table 6.0: ACSM Predicted 10 Minute Calories Watts 10 Min Indicated Kcal Predicted VO2 (L/Min) ACSM Predicted 10 Min...144 13 322 20 6 49 7.5 171 13.5 361 19.5 8 63 7 198 13.5 400 19.5 10 77 7 224 13 440 20 Total 71 132 197 RPM 60 60.7...min 300w Kcal/min Hours on Bike 0 45 138 285 3474 2 59 7 163 12.5 323 19 4 73 7 189 13 361 19 6 87 7 215 13 400 19.5 8 102 7.5 141

The Sphinx's Riddle: Life and Career Cycles.

ERIC Educational Resources Information Center

Burack, Elmer H.

1984-01-01

Career cycles should be considered apart from life cycles, even though the two are interrelated. This essay examines five theories about life and career cycles, and offers insights into their limitations and potential uses. (JB)

Exploring the microbially-mediated soil H2 sink: A lab-based study of the physiology and related H2 consumption of isolates from the Harvard Forest

NASA Astrophysics Data System (ADS)

Rao, D.; Meredith, L. K.; Bosak, T.; Hansel, C. M.; Ono, S.; Prinn, R. G.

2012-12-01

Atmospheric hydrogen (H2) is a secondary greenhouse gas because it attenuates the removal of methane (CH4) from the atmosphere. The largest and most uncertain term in the H2 biogeochemical cycle, microbe-mediated soil uptake, is responsible for about 80% of Earth's tropospheric H2 sink. Recently, the first H2-oxidizing soil microorganisms were discovered (genus Streptomyces) whose low-threshold, high-affinity NiFe-hydrogenase functions at ambient H2 levels (approx. 530 ppb). To better understand the ecological function of this hydrogenase, we conducted a controlled laboratory study of the H2 uptake behavior in accordance with the complex life cycle development of the streptomycetes. Several strains of the genus Streptomyces containing a high-affinity NiFe- hydrogenase were isolated from soil at the Harvard Forest. The presence of this hydrogenase, detected by PCR amplification of the hydrogenase large subunit, predicted H2 uptake behavior in wild-type streptomycetes and in phylogenetically different organisms containing more distantly related versions of the gene. H2 uptake depended on the streptomyces' life cycle, reaching a maximum during spore formation. These findings reveal connections between environmental conditions, organismal life cycle, and H2 uptake. With the rise of H2-based energy sources and a potential change in the tropospheric concentration of H2, understanding the sources and sinks of this trace gas is important for the future.

Life Cycle Energy Analysis of Reclaimed Water Reuse Projects in Beijing.

PubMed

Fan, Yupeng; Guo, Erhui; Zhai, Yuanzheng; Chang, Andrew C; Qiao, Qi; Kang, Peng

2018-01-01

  To illustrate the benefits of water reuse project, the process-based life cycle analysis (LCA) could be combined with input-output LCA to evaluate the water reuse project. Energy is the only evaluation parameter used in this study. Life cycle assessment of all energy inputs (LCEA) is completed mainly by the life cycle inventory (LCI), taking into account the full life cycle including the construction, the operation, and the demolition phase of the project. Assessment of benefit from water reuse during the life cycle should focus on wastewater discharge reduction and water-saving benefits. The results of LCEA of Beijing water reuse project built in 2014 in a comprehensive way shows that the benefits obtained from the reclaimed water reuse far exceed the life cycle energy consumption. In this paper, the authors apply the LCEA model to estimate the benefits of reclaimed water reuse projects quantitatively.

10 CFR 436.20 - Net savings.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Life Cycle Cost Analyses § 436.20 Net savings. For a retrofit project, net savings may be found by subtracting life cycle costs based on the proposed project from life cycle costs based on not having it. For a new building design, net savings is the difference between the life cycle costs of an alternative...

10 CFR 436.20 - Net savings.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Life Cycle Cost Analyses § 436.20 Net savings. For a retrofit project, net savings may be found by subtracting life cycle costs based on the proposed project from life cycle costs based on not having it. For a new building design, net savings is the difference between the life cycle costs of an alternative...

10 CFR 436.42 - Evaluation of Life-Cycle Cost Effectiveness.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 3 2014-01-01 2014-01-01 false Evaluation of Life-Cycle Cost Effectiveness. 436.42... PROGRAMS Agency Procurement of Energy Efficient Products § 436.42 Evaluation of Life-Cycle Cost...) ENERGY STAR qualified and FEMP designated products may be assumed to be life-cycle cost-effective. (b) In...

10 CFR 435.306 - Selecting a life cycle effective proposed building design.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 3 2013-01-01 2013-01-01 false Selecting a life cycle effective proposed building design... Residential Buildings § 435.306 Selecting a life cycle effective proposed building design. In selecting... prototype, has the highest Net Savings or lowest total life cycle costs calculated in compliance with...

10 CFR 436.42 - Evaluation of Life-Cycle Cost Effectiveness.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 3 2012-01-01 2012-01-01 false Evaluation of Life-Cycle Cost Effectiveness. 436.42... PROGRAMS Agency Procurement of Energy Efficient Products § 436.42 Evaluation of Life-Cycle Cost...) ENERGY STAR qualified and FEMP designated products may be assumed to be life-cycle cost-effective. (b) In...

10 CFR 436.42 - Evaluation of Life-Cycle Cost Effectiveness.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 3 2013-01-01 2013-01-01 false Evaluation of Life-Cycle Cost Effectiveness. 436.42... PROGRAMS Agency Procurement of Energy Efficient Products § 436.42 Evaluation of Life-Cycle Cost...) ENERGY STAR qualified and FEMP designated products may be assumed to be life-cycle cost-effective. (b) In...

10 CFR 435.306 - Selecting a life cycle effective proposed building design.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 3 2014-01-01 2014-01-01 false Selecting a life cycle effective proposed building design... Residential Buildings § 435.306 Selecting a life cycle effective proposed building design. In selecting... prototype, has the highest Net Savings or lowest total life cycle costs calculated in compliance with...

10 CFR 435.306 - Selecting a life cycle effective proposed building design.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 3 2012-01-01 2012-01-01 false Selecting a life cycle effective proposed building design... Residential Buildings § 435.306 Selecting a life cycle effective proposed building design. In selecting... prototype, has the highest Net Savings or lowest total life cycle costs calculated in compliance with...

10 CFR 436.20 - Net savings.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Life Cycle Cost Analyses § 436.20 Net savings. For a retrofit project, net savings may be found by subtracting life cycle costs based on the proposed project from life cycle costs based on not having it. For a new building design, net savings is the difference between the life cycle costs of an alternative...

10 CFR 433.8 - Life-cycle costing.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 3 2011-01-01 2011-01-01 false Life-cycle costing. 433.8 Section 433.8 Energy DEPARTMENT... FEDERAL COMMERCIAL AND MULTI-FAMILY HIGH-RISE RESIDENTIAL BUILDINGS § 433.8 Life-cycle costing. Each Federal agency shall determine life-cycle cost-effectiveness by using the procedures set out in subpart A...

78 FR 47012 - Developing Software Life Cycle Processes Used in Safety Systems of Nuclear Power Plants

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-02

... NUCLEAR REGULATORY COMMISSION [NRC-2012-0195] Developing Software Life Cycle Processes Used in... revised regulatory guide (RG), revision 1 of RG 1.173, ``Developing Software Life Cycle Processes for... Developing a Software Project Life Cycle Process,'' issued 2006, with the clarifications and exceptions as...

10 CFR 433.8 - Life-cycle costing.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Life-cycle costing. 433.8 Section 433.8 Energy DEPARTMENT... FEDERAL COMMERCIAL AND MULTI-FAMILY HIGH-RISE RESIDENTIAL BUILDINGS § 433.8 Life-cycle costing. Each Federal agency shall determine life-cycle cost-effectiveness by using the procedures set out in subpart A...

DEVELOPMENT OF THE METHOD AND U.S. NORMALIZATION DATABASE FOR LIFE CYCLE IMPACT ASSESSMENT AND SUSTAINABILITY METRICS

EPA Science Inventory

Normalization is an optional step within Life Cycle Impact Assessment (LCIA) that may be used to assist in the interpretation of life cycle inventory data as well as, life cycle impact assessment results. Normalization transforms the magnitude of LCI and LCIA results into relati...

10 CFR 436.42 - Evaluation of Life-Cycle Cost Effectiveness.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Evaluation of Life-Cycle Cost Effectiveness. 436.42... PROGRAMS Agency Procurement of Energy Efficient Products § 436.42 Evaluation of Life-Cycle Cost...) ENERGY STAR qualified and FEMP designated products may be assumed to be life-cycle cost-effective. (b) In...

10 CFR 435.306 - Selecting a life cycle effective proposed building design.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Selecting a life cycle effective proposed building design... Residential Buildings § 435.306 Selecting a life cycle effective proposed building design. In selecting... prototype, has the highest Net Savings or lowest total life cycle costs calculated in compliance with...

Residential Preferences and Moving Behavior: A Family Life Cycle Analysis.

ERIC Educational Resources Information Center

McAuley, William J.; Nutty, Cheri L.

The relationship of family life cycle changes to housing preferences and residential mobility is examined. Two residential decision-making issues are explored in detail--how family life cycle stages influence what people view as important to their choice of residential setting and what individuals at different family life cycle stages view as the…

10 CFR 436.20 - Net savings.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Life Cycle Cost Analyses § 436.20 Net savings. For a retrofit project, net savings may be found by subtracting life cycle costs based on the proposed project from life cycle costs based on not having it. For a new building design, net savings is the difference between the life cycle costs of an alternative...

10 CFR 436.20 - Net savings.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Life Cycle Cost Analyses § 436.20 Net savings. For a retrofit project, net savings may be found by subtracting life cycle costs based on the proposed project from life cycle costs based on not having it. For a new building design, net savings is the difference between the life cycle costs of an alternative...

10 CFR 436.42 - Evaluation of Life-Cycle Cost Effectiveness.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the life-cycle cost analysis method in part 436, subpart A, of title 10 of the Code of Federal... 10 Energy 3 2011-01-01 2011-01-01 false Evaluation of Life-Cycle Cost Effectiveness. 436.42... PROGRAMS Agency Procurement of Energy Efficient Products § 436.42 Evaluation of Life-Cycle Cost...

Argonne National Laboratory Li-alloy/FeS cell testing and R and D programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gay, E.C.

1982-01-01

Groups of 12 or more identical Li-alloy/FeS cells fabricated by Eagle-Picher Industries, Inc. and Gould Inc. were operated at Argonne National Laboratory (ANL) in the status cell test program to obtain data for statistical analysis of cell cycle life and failure modes. The cells were full-size electric vehicle battery cells (150 to 350 Ah capacity) and they were cycled at the 4-h discharge rate and 8-h charge rate. The end of life was defined as a 20% loss of capacity or a decrease in the coulombic efficiency to less than 95%. Seventy-four cells (six groups of identical cells) were cycle-lifemore » tested and the results were analyzed statistically. The ultimate goal of this analysis was to predict cell and battery reliability. Testing of groups of identical cells also provided a means of identifying common failure modes which were eliminated by cell design changes. Mean time to failure (MTTF) for the cells based on the Weibull distribution is presented.« less

Effect of temperature and salinity on egg hatching and description of the life cycle of Lernanthropus latis (Copepoda: Lernanthropidae) infecting barramundi, Lates calcarifer.

PubMed

Brazenor, Alexander K; Hutson, Kate S

2013-10-01

The parasite Lernanthropus latis (Copepoda: Lernanthropidae) is a major threat to the sustained mariculture of barramundi, Lates calcarifer (Perciformes: Latidae). We investigated the effect of water temperature and salinity on egg hatching success of L. latis and describe the life cycle for the first time. Wild and sea-caged L. calcarifer examined in tropical north Australia exhibited similar parasite prevalence (range: 80-100%) and mean parasite intensity (range: 3-6), whereas land-based maricultured fish were not infected. Hatching success and time to first and last hatch was determined for a range of water temperature (22, 30, 32 and 34°C) and salinity (0, 11, 22, 35 and 40‰) combinations representing current and predicted climate conditions. There was a significant interaction between water temperature and salinity on the hatching success of L. latis nauplii. Eggs hatched in all temperature treatments, with the greatest hatching success at 30°C and 32°C (98 and 92% success, respectively) in 35‰. Hatching did not occur at 0‰ and was severely reduced at 11‰ (1.6% success). Hatching began within 6h at all water temperatures with >95% of eggs hatched within 30h at 30, 32 and 34°C and within 60h at 22°C. Adult parasites differed from the original description by the presence of the parabasal flagellum, small setae on the legs and caudal rami and minor incongruences regarding morphological measurements. The life cycle of L. latis includes three free living stages and five parasitic stages. Although L. latis exhibits broad environmental tolerance, freshwater can be used as an effective management strategy to break the life cycle in aquaculture. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Uncertainty quantification metrics for whole product life cycle cost estimates in aerospace innovation

NASA Astrophysics Data System (ADS)

Schwabe, O.; Shehab, E.; Erkoyuncu, J.

2015-08-01

The lack of defensible methods for quantifying cost estimate uncertainty over the whole product life cycle of aerospace innovations such as propulsion systems or airframes poses a significant challenge to the creation of accurate and defensible cost estimates. Based on the axiomatic definition of uncertainty as the actual prediction error of the cost estimate, this paper provides a comprehensive overview of metrics used for the uncertainty quantification of cost estimates based on a literature review, an evaluation of publicly funded projects such as part of the CORDIS or Horizon 2020 programs, and an analysis of established approaches used by organizations such NASA, the U.S. Department of Defence, the ESA, and various commercial companies. The metrics are categorized based on their foundational character (foundations), their use in practice (state-of-practice), their availability for practice (state-of-art) and those suggested for future exploration (state-of-future). Insights gained were that a variety of uncertainty quantification metrics exist whose suitability depends on the volatility of available relevant information, as defined by technical and cost readiness level, and the number of whole product life cycle phases the estimate is intended to be valid for. Information volatility and number of whole product life cycle phases can hereby be considered as defining multi-dimensional probability fields admitting various uncertainty quantification metric families with identifiable thresholds for transitioning between them. The key research gaps identified were the lacking guidance grounded in theory for the selection of uncertainty quantification metrics and lacking practical alternatives to metrics based on the Central Limit Theorem. An innovative uncertainty quantification framework consisting of; a set-theory based typology, a data library, a classification system, and a corresponding input-output model are put forward to address this research gap as the basis for future work in this field.

Predictive modeling and reducing cyclic variability in autoignition engines

DOEpatents

Hellstrom, Erik; Stefanopoulou, Anna; Jiang, Li; Larimore, Jacob

2016-08-30

Methods and systems are provided for controlling a vehicle engine to reduce cycle-to-cycle combustion variation. A predictive model is applied to predict cycle-to-cycle combustion behavior of an engine based on observed engine performance variables. Conditions are identified, based on the predicted cycle-to-cycle combustion behavior, that indicate high cycle-to-cycle combustion variation. Corrective measures are then applied to prevent the predicted high cycle-to-cycle combustion variation.

Application of Different Statistical Techniques in Integrated Logistics Support of the International Space Station Alpha

NASA Technical Reports Server (NTRS)

Sepehry-Fard, F.; Coulthard, Maurice H.

1995-01-01

The process to predict the values of the maintenance time dependent variable parameters such as mean time between failures (MTBF) over time must be one that will not in turn introduce uncontrolled deviation in the results of the ILS analysis such as life cycle cost spares calculation, etc. A minor deviation in the values of the maintenance time dependent variable parameters such as MTBF over time will have a significant impact on the logistics resources demands, International Space Station availability, and maintenance support costs. It is the objective of this report to identify the magnitude of the expected enhancement in the accuracy of the results for the International Space Station reliability and maintainability data packages by providing examples. These examples partially portray the necessary information hy evaluating the impact of the said enhancements on the life cycle cost and the availability of the International Space Station.

Sampling and monitoring for closure

USGS Publications Warehouse

McLemore, V.T.; Russell, C.C.; Smith, K.S.

2004-01-01

The Metals Mining Sector of the Acid Drainage Technology Initiative (ADTI-MMS) addresses technical drainage-quality issues related to metal mining and related metallurgical operations, for future and active mines, as well as, for historical mines and mining districts. One of the first projects of ADTI-MMS is to develop a handbook describing the best sampling, monitoring, predicting, mitigating, and modeling of drainage from metal mines, pit lakes and related metallurgical facilities based upon current scientific and engineering practices. One of the important aspects of planning a new mine in today's regulatory environment is the philosophy of designing a new or existing mine or expansion of operations for ultimate closure. The holistic philosophy taken in the ADTI-MMS handbook maintains that sampling and monitoring programs should be designed to take into account all aspects of the mine-life cycle. Data required for the closure of the operation are obtained throughout the mine-life cycle, from exploration through post-closure.

The 2017 Hurricane Season: A Revolution in Geostationary Weather Satellite Imaging and Data Processing

NASA Astrophysics Data System (ADS)

Weiner, A. M.; Gundy, J.; Brown-Bertold, B.; Yates, H.; Dobler, J. T.

2017-12-01

Since their introduction, geostationary weather satellites have enabled us to track hurricane life-cycle movement from development to dissipation. During the 2017 hurricane season, the new GOES-16 geostationary satellite demonstrated just how far we have progressed technologically in geostationary satellite imaging, with hurricane imagery showing never-before-seen detail of the hurricane eye and eyewall structure and life cycle. In addition, new ground system technology, leveraging high-performance computing, delivered imagery and data to forecasters with unprecedented speed—and with updates as often as every 30 seconds. As additional satellites and new products become operational, forecasters will be able to track hurricanes with even greater accuracy and assist in aftermath evaluations. This presentation will present glimpses into the past, a look at the present, and a prediction for the future utilization of geostationary satellites with respect to all facets of hurricane support.

Predictive Service Life Tests for Roofing Membranes

NASA Astrophysics Data System (ADS)

Bailey, David M.; Cash, Carl G.; Davies, Arthur G.

2002-09-01

The average service life of roofing membranes used in low-slope applications on U.S. Army buildings is estimated to be considerably shorter than the industry-presumed 20-year design life, even when installers carefully adhere to the latest guide specifications. This problem is due in large part to market-driven product development cycles, which do not include time for long-term field testing. To reduce delivery costs, contractors may provide untested, interior membranes in place of ones proven satisfactory in long-term service. Federal procurement regulations require that roofing systems and components be selected according to desired properties and generic type, not brand name. The problem is that a material certified to have satisfactory properties at installation time will not necessarily retain those properties in service. The overall objective of this research is to develop a testing program that can be executed in a matter of weeks to adequately predict a membrane's long-term performance in service. This report details accelerated aging tests of 12 popular membrane materials in the laboratory, and describes outdoor experiment stations set up for long-term exposure tests of those same membranes. The laboratory results will later be correlated with the outdoor test results to develop performance models and predictive service life tests.

Investigation of fatigue assessments accuracy for beam weldments considering material data input and FE-mode type

NASA Astrophysics Data System (ADS)

Gorash, Yevgen; Comlekci, Tugrul; MacKenzie, Donald

2017-05-01

This study investigates the effects of fatigue material data and finite element types on accuracy of residual life assessments under high cycle fatigue. The bending of cross-beam connections is simulated in ANSYS Workbench for different combinations of structural member shapes made of a typical structural steel. The stress analysis of weldments with specific dimensions and loading applied is implemented using solid and shell elements. The stress results are transferred to the fatigue code nCode DesignLife for the residual life prediction. Considering the effects of mean stress using FKM approach, bending and thickness according to BS 7608:2014, fatigue life is predicted using the Volvo method and stress integration rules from ASME Boiler & Pressure Vessel Code. Three different pairs of S-N curves are considered in this work including generic seam weld curves and curves for the equivalent Japanese steel JIS G3106-SM490B. The S-N curve parameters for the steel are identified using the experimental data available from NIMS fatigue data sheets employing least square method and considering thickness and mean stress corrections. The numerical predictions are compared to the available experimental results indicating the most preferable fatigue data input, range of applicability and FE-model formulation to achieve the best accuracy.

Strain-Life Assessment of Grainex Mar-M 247 for NASA's Turbine Seal Test Facility

NASA Technical Reports Server (NTRS)

Delgado, Irebert R.; Halford, Gary R.; Steinetz, Bruce M.; Rimnac, Clare M.

2004-01-01

NASA s Turbine Seal Test Facility is used to test air-to-air seals for use primarily in advanced jet engine applications. Combinations of high temperature, high speed, and high pressure limit the disk life, due to the concern of crack initiation in the bolt holes of the Grainex Mar-M 247 disk. The primary purpose of this current work is to determine an inspection interval to ensure safe operation. The current work presents high temperature fatigue strain-life data for test specimens cut from an actual Grainex Mar-M 247 disk. Several different strain-life models were compared to the experimental data including the Manson-Hirschberg Method of Universal Slopes, the Halford-Nachtigall Mean Stress Method, and the Modified Morrow Method. The Halford-Nachtigall Method resulted in only an 18 percent difference between predicted and experimental results. Using the experimental data at a 99.95 percent prediction level and the presence of 6 bolt holes it was found that the disk should be inspected after 665 cycles based on a total strain of 0.5 percent at 649 C.

Life history determines genetic structure and evolutionary potential of host–parasite interactions

PubMed Central

Barrett, Luke G.; Thrall, Peter H.; Burdon, Jeremy J.; Linde, Celeste C.

2009-01-01

Measures of population genetic structure and diversity of disease-causing organisms are commonly used to draw inferences regarding their evolutionary history and potential to generate new variation in traits that determine interactions with their hosts. Parasite species exhibit a range of population structures and life-history strategies, including different transmission modes, life-cycle complexity, off-host survival mechanisms and dispersal ability. These are important determinants of the frequency and predictability of interactions with host species. Yet the complex causal relationships between spatial structure, life history and the evolutionary dynamics of parasite populations are not well understood. We demonstrate that a clear picture of the evolutionary potential of parasitic organisms and their demographic and evolutionary histories can only come from understanding the role of life history and spatial structure in influencing population dynamics and epidemiological patterns. PMID:18947899

Life history determines genetic structure and evolutionary potential of host-parasite interactions.

PubMed

Barrett, Luke G; Thrall, Peter H; Burdon, Jeremy J; Linde, Celeste C

2008-12-01

Measures of population genetic structure and diversity of disease-causing organisms are commonly used to draw inferences regarding their evolutionary history and potential to generate new variation in traits that determine interactions with their hosts. Parasite species exhibit a range of population structures and life-history strategies, including different transmission modes, life-cycle complexity, off-host survival mechanisms and dispersal ability. These are important determinants of the frequency and predictability of interactions with host species. Yet the complex causal relationships between spatial structure, life history and the evolutionary dynamics of parasite populations are not well understood. We demonstrate that a clear picture of the evolutionary potential of parasitic organisms and their demographic and evolutionary histories can only come from understanding the role of life history and spatial structure in influencing population dynamics and epidemiological patterns.

Effects of climate change and variability on population dynamics in a long-lived shorebird.

PubMed

van de Pol, Martijn; Vindenes, Yngvild; Saether, Bernt-Erik; Engen, Steinar; Ens, Bruno J; Oosterbeek, Kees; Tinbergen, Joost M

2010-04-01

Climate change affects both the mean and variability of climatic variables, but their relative impact on the dynamics of populations is still largely unexplored. Based on a long-term study of the demography of a declining Eurasian Oystercatcher (Haematopus ostralegus) population, we quantify the effect of changes in mean and variance of winter temperature on different vital rates across the life cycle. Subsequently, we quantify, using stochastic stage-structured models, how changes in the mean and variance of this environmental variable affect important characteristics of the future population dynamics, such as the time to extinction. Local mean winter temperature is predicted to strongly increase, and we show that this is likely to increase the population's persistence time via its positive effects on adult survival that outweigh the negative effects that higher temperatures have on fecundity. Interannual variation in winter temperature is predicted to decrease, which is also likely to increase persistence time via its positive effects on adult survival that outweigh the negative effects that lower temperature variability has on fecundity. Overall, a 0.1 degrees C change in mean temperature is predicted to alter median time to extinction by 1.5 times as many years as would a 0.1 degrees C change in the standard deviation in temperature, suggesting that the dynamics of oystercatchers are more sensitive to changes in the mean than in the interannual variability of this climatic variable. Moreover, as climate models predict larger changes in the mean than in the standard deviation of local winter temperature, the effects of future climatic variability on this population's time to extinction are expected to be overwhelmed by the effects of changes in climatic means. We discuss the mechanisms by which climatic variability can either increase or decrease population viability and how this might depend both on species' life histories and on the vital rates affected. This study illustrates that, for making reliable inferences about population consequences in species in which life history changes with age or stage, it is crucial to investigate the impact of climate change on vital rates across the entire life cycle. Disturbingly, such data are unavailable for most species of conservation concern.

KOH concentration effect on cycle life of nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Lim, Hong S.; Verzwyvelt, S. A.

1987-01-01

A cycle life test of Ni/H2 cells containing electrolytes of various KOH concentrations and a sintered type nickel electrode was carried out at 23 C using a 45 min accelerated low Earth orbit (LEO) cycle regime at 80 percent depth of discharge. One of three cells containing 26 percent KOH has achieved over 28,000 cycles, and the other two 19,000 cycles, without a sign of failure. Two other cells containing 31 percent KOH electrolyte, which is the concentration presently used in aerospace cells, failed after 2,979 and 3,620 cycles. This result indicates that the cycle life of the present type of Ni/H2 cells may be extended by a factor of 5 to 10 simply by lowering the KOH concentration. Long cycle life of a Ni/H2 battery at high depth-of-discharge operation is desired, particularly for an LEO spacecraft application. Typically, battery life of about 30,000 cycles is required for a five year mission in an LEO. Such a cycle life with presently available cells can be assured only at a very low depth-of-discharge operation. Results of testing already show that the cycle life of an Ni/H2 cell is tremendously improved by simply using an electrolyte of low KOH concentration.

10 CFR 455.64 - Life-cycle cost methodology.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 3 2011-01-01 2011-01-01 false Life-cycle cost methodology. 455.64 Section 455.64 Energy..., Hospitals, Units of Local Government, and Public Care Institutions § 455.64 Life-cycle cost methodology. (a) The life-cycle cost methodology under § 455.63(b) of this part is a systematic comparison of the...

NREL: U.S. Life Cycle Inventory Database - About the LCI Database Project

Science.gov Websites

About the LCI Database Project The U.S. Life Cycle Inventory (LCI) Database is a publicly available data collection and analysis methods. Finding consistent and transparent LCI data for life cycle and maintain the database. The 2009 U.S. Life Cycle Inventory (LCI) Data Stakeholder meeting was an

10 CFR 455.64 - Life-cycle cost methodology.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Life-cycle cost methodology. 455.64 Section 455.64 Energy..., Hospitals, Units of Local Government, and Public Care Institutions § 455.64 Life-cycle cost methodology. (a) The life-cycle cost methodology under § 455.63(b) of this part is a systematic comparison of the...

Alternative Fuels Data Center: Benefits and Considerations of Electricity

Science.gov Websites

tailpipe emissions when in all-electric mode. The life cycle emissions of an EV or PHEV depend on the low-polluting energy sources for electricity production, plug-in vehicles typically have a life cycle strong life cycle emissions benefit. Use the Vehicle Cost Calculator to compare life cycle emissions of

UTILITY OF A FULL LIFE-CYCLE COPEPOD BIOASSAY APPROACH FOR ASSESSMENT OF SEDIMENT-ASSOCIATED CONTAMINANT MIXTURES. (R825279)

EPA Science Inventory

Abstract

We compared a 21 day full life-cycle bioassay with an existing 14 day partial life-cycle bioassay for two species of meiobenthic copepods, Microarthridion littorale and Amphiascus tenuiremis. We hypothesized that full life-cycle tests would bette...

The Early Years: "Life" Science

ERIC Educational Resources Information Center

Ashbrook, Peggy

2013-01-01

Talking about death as part of a life cycle is often ignored or spoken about in hushed tones in early childhood. Books with "life cycle" in the title often do not include the death of the living organism in the information about the cycle. The concept of a complete life cycle does not appear in "A Framework for K-12 Science…

[Relationship between family variables and conjugal adjustment].

PubMed

Jiménez-Picón, Nerea; Lima-Rodríguez, Joaquín-Salvador; Lima-Serrano, Marta

2018-04-01

To determine whether family variables, such as type of relationship, years of marriage, existence of offspring, number of members of family, stage of family life cycle, transition between stages, perceived social support, and/or stressful life events are related to conjugal adjustment. A cross-sectional and correlational study using questionnaires. Primary care and hospital units of selected centres in the province of Seville, Spain. Consecutive stratified sampling by quotas of 369 heterosexual couples over 18years of age, who maintained a relationship, with or without children, living in Seville. A self-report questionnaire for the sociodemographic variables, and the abbreviated version of the Dyadic Adjustment Scale, Questionnaire MOS Perceived Social Support, and Social Readjustment Rating Scale, were used. Descriptive and inferential statistics were performed with correlation analysis and multivariate regression. Statistically significant associations were found between conjugal adjustment and marriage years (r=-10: P<.05), stage of family life cycle (F=2.65; P<.05), the transition between stages (RPB=.11; P<.05) and perceived social support (r=.44; P<.001). The regression model showed the predictive power of perceived social support and the family life cycle stage (mature-aged stage) on conjugal adjustment (R2=.21; F=9.9; df=356; P<.001). Couples may be assessed from Primary Care and be provide with resources and support. In addition, it can identify variables that may help improve the conjugal relationship. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Comparison of oxaliplatin and paclitaxel-induced neuropathy (Alliance A151505).

PubMed

Pachman, Deirdre R; Qin, Rui; Seisler, Drew; Smith, Ellen M Lavoie; Kaggal, Suneetha; Novotny, Paul; Ruddy, Kathryn J; Lafky, Jacqueline M; Ta, Lauren E; Beutler, Andreas S; Wagner-Johnston, Nina D; Staff, Nathan P; Grothey, Axel; Dougherty, Patrick M; Cavaletti, Guido; Loprinzi, Charles L

2016-12-01

Oxaliplatin and paclitaxel are commonly used chemotherapies associated with acute and chronic neuropathies. There is a need to better understand the similarities and differences of these clinical syndromes. Neuropathy data were pooled from patients receiving adjuvant oxaliplatin and weekly paclitaxel or every 3 weeks of paclitaxel. Patients completed daily questionnaires after each chemotherapy dose and the European Organization for Research and Treatment of Cancer quality-of-life questionnaire for patients with chemotherapy-induced peripheral neuropathy before each chemotherapy cycle and for 12 months post-treatment. Acute neuropathy symptoms from both drugs peaked around day 3. Acute symptoms experienced in cycle 1 predicted occurrence in subsequent cycles. Paclitaxel-induced acute symptoms were similar in intensity in each cycle and largely resolved between cycles. Oxaliplatin-induced acute symptoms were about half as severe in the first cycle as in later cycles and did not resolve completely between cycles. Both drugs caused a predominantly sensory chronic neuropathy (with numbness and tingling being more common than pain). Oxaliplatin-induced neuropathy worsened after the completion of treatment and began to improve 3 months post-treatment. In contrast, paclitaxel-induced neuropathy began improving immediately after chemotherapy cessation. During treatment, the incidence of paclitaxel sensory symptoms was similar in the hands and feet; with oxaliplatin, the hands were affected more than the feet. Both paclitaxel- and oxaliplatin-induced acute neurotoxicity appeared to predict the severity of chronic neuropathy, more prominently with oxaliplatin. Knowledge of the similarities and differences between neuropathy syndromes may provide insight into their underlying pathophysiology and inform future research to identify preventative treatment approaches.

Alberta Carpenter | NREL

Science.gov Websites

cycle assessment in industrial by-product management, waste management, biofuels and manufacturing technologies Life cycle inventory database management Research Interests Life cycle assessment Life cycle inventory management Biofuels Advanced manufacturing Supply chain analysis Education Ph.D in environmental

Outbrief - Long Life Rocket Engine Panel

NASA Technical Reports Server (NTRS)

Quinn, Jason Eugene

2004-01-01

This white paper is an overview of the JANNAF Long Life Rocket Engine (LLRE) Panel results from the last several years of activity. The LLRE Panel has met over the last several years in order to develop an approach for the development of long life rocket engines. Membership for this panel was drawn from a diverse set of the groups currently working on rocket engines (Le. government labs, both large and small companies and university members). The LLRE Panel was formed in order to determine the best way to enable the design of rocket engine systems that have life capability greater than 500 cycles while meeting or exceeding current performance levels (Specific Impulse and Thrust/Weight) with a 1/1,OOO,OOO likelihood of vehicle loss due to rocket system failure. After several meetings and much independent work the panel reached a consensus opinion that the primary issues preventing LLRE are a lack of: physics based life prediction, combined loads prediction, understanding of material microphysics, cost effective system level testing. and the inclusion of fabrication process effects into physics based models. With the expected level of funding devoted to LLRE development, the panel recommended that fundamental research efforts focused on these five areas be emphasized.

NREL: U.S. Life Cycle Inventory Database - Publications

Science.gov Websites

Publications Planning Documents U.S. Life Cycle Inventory Database Roadmap, February 2009 U.S. Life Cycle Inventory User Survey, February 2009 U.S. LCI Database Factsheet, March 2005 User's Guide for Life

Autonomy and integration in complex parasite life cycles.

PubMed

Benesh, Daniel P

2016-12-01

Complex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.

Accurate Determination of Coulombic Efficiency for Lithium Metal Anodes and Lithium Metal Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, Brian D.; Zheng, Jianming; Ren, Xiaodi

Lithium (Li) metal is an ideal anode material for high energy density batteries. However, its low Coulombic efficiency (CE) and formation of dendrites during the plating and stripping processes has hindered its applications in rechargeable Li metal batteries. The accurate measurement of Li CE is a critical factor to predict the cycle life of Li metal batteries, but the measurement of Li CE is affected by various factors that often leads to conflicting values reported in the literature. Here, we investigate various factors that affect the measurement of Li CE and propose a more accurate method of determining Li CE.more » It was also found that the capacity used for cycling greatly affects the stabilization cycles and the average CE. A higher cycling capacity leads to a shorter number of stabilization cycles and higher average CE. With a proper high-concentration ether-based electrolyte, Li metal can be cycled with a high average CE of 99.5 % for over 100 cycles at a high capacity of 6 mAh cm-2 suitable for practical applications.« less

Experimental and analytical study of ceramic-coated turbine-tip shroud seals for small turbine engines

NASA Technical Reports Server (NTRS)

Biesiadny, T. J.; Mcdonald, G. E.; Hendricks, R. C.; Little, J. K.; Robinson, R. A.; Klann, G. A.; Lassow, E. S.

1985-01-01

The results of an experimental and analytical evaluation of ceramic turbine tip shrouds within a small turbine engine operating environment are presented. The ceramic shrouds were subjected to 1001 cycles between idle and high power and steady-state conditions for a total of 57.8 engine hr. Posttest engine inspection revealed mud-flat surface cracking, which was attributed to microcracking under tension with crack penetration to the ceramic and bond coat interface. Sections and micrographs tend to corroborate the thesis. The engine test data provided input to a thermomechanical analysis to predict temperature and stress profiles throughout the ceramic gas-path seal. The analysis predicts cyclic thermal stresses large enough to cause the seal to fail. These stresses are, however, mitigated by inelastic behavior of the shroud materials and by the microfracturing that tensile stresses produce. Microfracturing enhances shroud longevity during early life but provides the failure mechanism during life but provides the failure mechanism during extended life when coupled with the time dependent inelastic materials effects.

The Interaction between Vector Life History and Short Vector Life in Vector-Borne Disease Transmission and Control.

PubMed

Brand, Samuel P C; Rock, Kat S; Keeling, Matt J

2016-04-01

Epidemiological modelling has a vital role to play in policy planning and prediction for the control of vectors, and hence the subsequent control of vector-borne diseases. To decide between competing policies requires models that can generate accurate predictions, which in turn requires accurate knowledge of vector natural histories. Here we highlight the importance of the distribution of times between life-history events, using short-lived midge species as an example. In particular we focus on the distribution of the extrinsic incubation period (EIP) which determines the time between infection and becoming infectious, and the distribution of the length of the gonotrophic cycle which determines the time between successful bites. We show how different assumptions for these periods can radically change the basic reproductive ratio (R0) of an infection and additionally the impact of vector control on the infection. These findings highlight the need for detailed entomological data, based on laboratory experiments and field data, to correctly construct the next-generation of policy-informing models.

Climate change in fish: effects of respiratory constraints on optimal life history and behaviour.

PubMed

Holt, Rebecca E; Jørgensen, Christian

2015-02-01

The difference between maximum metabolic rate and standard metabolic rate is referred to as aerobic scope, and because it constrains performance it is suggested to constitute a key limiting process prescribing how fish may cope with or adapt to climate warming. We use an evolutionary bioenergetics model for Atlantic cod (Gadus morhua) to predict optimal life histories and behaviours at different temperatures. The model assumes common trade-offs and predicts that optimal temperatures for growth and fitness lie below that for aerobic scope; aerobic scope is thus a poor predictor of fitness at high temperatures. Initially, warming expands aerobic scope, allowing for faster growth and increased reproduction. Beyond the optimal temperature for fitness, increased metabolic requirements intensify foraging and reduce survival; oxygen budgeting conflicts thus constrain successful completion of the life cycle. The model illustrates how physiological adaptations are part of a suite of traits that have coevolved. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

10 CFR 436.10 - Purpose.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Cycle Cost Analyses § 436.10 Purpose. This subpart establishes a methodology and procedures for estimating and comparing the life cycle costs of Federal buildings, for determining the life cycle cost effectiveness of energy conservation measures and water conservation measures, and for rank ordering life cycle...

Shortening tobacco life cycle accelerates functional gene identification in genomic research.

PubMed

Ning, G; Xiao, X; Lv, H; Li, X; Zuo, Y; Bao, M

2012-11-01

Definitive allocation of function requires the introduction of genetic mutations and analysis of their phenotypic consequences. Novel, rapid and convenient techniques or materials are very important and useful to accelerate gene identification in functional genomics research. Here, over-expression of PmFT (Prunus mume), a novel FT orthologue, and PtFT (Populus tremula) lead to shortening of the tobacco life cycle. A series of novel short life cycle stable tobacco lines (30-50 days) were developed through repeated self-crossing selection breeding. Based on the second transformation via a gusA reporter gene, the promoter from BpFULL1 in silver birch (Betula pendula) and the gene (CPC) from Arabidopsis thaliana were effectively tested using short life cycle tobacco lines. Comparative analysis among wild type, short life cycle tobacco and Arabidopsis transformation system verified that it is optional to accelerate functional gene studies by shortening host plant material life cycle, at least in these short life cycle tobacco lines. The results verified that the novel short life cycle transgenic tobacco lines not only combine the advantages of economic nursery requirements and a simple transformation system, but also provide a robust, effective and stable host system to accelerate gene analysis. Thus, shortening tobacco life cycle strategy is feasible to accelerate heterologous or homologous functional gene identification in genomic research. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Structures Division

NASA Technical Reports Server (NTRS)

1997-01-01

The NASA Lewis Research Center Structures Division is an international leader and pioneer in developing new structural analysis, life prediction, and failure analysis related to rotating machinery and more specifically to hot section components in air-breathing aircraft engines and spacecraft propulsion systems. The research consists of both deterministic and probabilistic methodology. Studies include, but are not limited to, high-cycle and low-cycle fatigue as well as material creep. Studies of structural failure are at both the micro- and macrolevels. Nondestructive evaluation methods related to structural reliability are developed, applied, and evaluated. Materials from which structural components are made, studied, and tested are monolithics and metal-matrix, polymer-matrix, and ceramic-matrix composites. Aeroelastic models are developed and used to determine the cyclic loading and life of fan and turbine blades. Life models are developed and tested for bearings, seals, and other mechanical components, such as magnetic suspensions. Results of these studies are published in NASA technical papers and reference publication as well as in technical society journal articles. The results of the work of the Structures Division and the bibliography of its publications for calendar year 1995 are presented.

Structures Division 1994 Annual Report

NASA Technical Reports Server (NTRS)

1996-01-01

The NASA Lewis Research Center Structures Division is an international leader and pioneer in developing new structural analysis, life prediction, and failure analysis related to rotating machinery and more specifically to hot section components in air-breathing aircraft engines and spacecraft propulsion systems. The research consists of both deterministic and probabilistic methodology. Studies include, but are not limited to, high-cycle and low-cycle fatigue as well as material creep. Studies of structural failure are at both the micro- and macrolevels. Nondestructive evaluation methods related to structural reliability are developed, applied, and evaluated. Materials from which structural components are made, studied, and tested are monolithics and metal-matrix, polymer-matrix, and ceramic-matrix composites. Aeroelastic models are developed and used to determine the cyclic loading and life of fan and turbine blades. Life models are developed and tested for bearings, seals, and other mechanical components, such as magnetic suspensions. Results of these studies are published in NASA technical papers and reference publication as well as in technical society journal articles. The results of the work of the Structures Division and the bibliography of its publications for calendar year 1994 are presented.

Integrating prospective longitudinal data: modeling personality and health in the Terman Life Cycle and Hawaii Longitudinal Studies.

PubMed

Kern, Margaret L; Hampson, Sarah E; Goldberg, Lewis R; Friedman, Howard S

2014-05-01

The present study used a collaborative framework to integrate 2 long-term prospective studies: the Terman Life Cycle Study and the Hawaii Personality and Health Longitudinal Study. Within a 5-factor personality-trait framework, teacher assessments of child personality were rationally and empirically aligned to establish similar factor structures across samples. Comparable items related to adult self-rated health, education, and alcohol use were harmonized, and data were pooled on harmonized items. A structural model was estimated as a multigroup analysis. Harmonized child personality factors were then used to examine markers of physiological dysfunction in the Hawaii sample and mortality risk in the Terman sample. Harmonized conscientiousness predicted less physiological dysfunction in the Hawaii sample and lower mortality risk in the Terman sample. These results illustrate how collaborative, integrative work with multiple samples offers the exciting possibility that samples from different cohorts and ages can be linked together to directly test life span theories of personality and health. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

NREL, Johns Hopkins SAIS Develop Method to Quantify Life Cycle Land Use of

Science.gov Websites

Life Cycle Land Use of Electricity from Natural Gas News Release: NREL, Johns Hopkins SAIS Develop Method to Quantify Life Cycle Land Use of Electricity from Natural Gas October 2, 2017 A case study of time provides quantifiable information on the life cycle land use of generating electricity from

REPORT ON ACTIVITY OF TASK FORCE 1 IN THE LIFE CYCLE INVENTORY PROGRAMME: DATA REGISTRY - GLOBAL LIFE CYCLE INVENTORY DATA RESOURCES

EPA Science Inventory

This paper presents a summary of the findings of a report prepared by Task Force 1 of the UNEP/SETAC Life Cycle Initiative on the available Life Cycle Inventory (LCI) databases around the world. An update of a previous summary prepared in May 2002 by Norris and Notten, the repor...

Understanding future emissions from low-carbon power systems by integration of life-cycle assessment and integrated energy modelling

NASA Astrophysics Data System (ADS)

Pehl, Michaja; Arvesen, Anders; Humpenöder, Florian; Popp, Alexander; Hertwich, Edgar G.; Luderer, Gunnar

2017-12-01

Both fossil-fuel and non-fossil-fuel power technologies induce life-cycle greenhouse gas emissions, mainly due to their embodied energy requirements for construction and operation, and upstream CH4 emissions. Here, we integrate prospective life-cycle assessment with global integrated energy-economy-land-use-climate modelling to explore life-cycle emissions of future low-carbon power supply systems and implications for technology choice. Future per-unit life-cycle emissions differ substantially across technologies. For a climate protection scenario, we project life-cycle emissions from fossil fuel carbon capture and sequestration plants of 78-110 gCO2eq kWh-1, compared with 3.5-12 gCO2eq kWh-1 for nuclear, wind and solar power for 2050. Life-cycle emissions from hydropower and bioenergy are substantial (˜100 gCO2eq kWh-1), but highly uncertain. We find that cumulative emissions attributable to upscaling low-carbon power other than hydropower are small compared with direct sectoral fossil fuel emissions and the total carbon budget. Fully considering life-cycle greenhouse gas emissions has only modest effects on the scale and structure of power production in cost-optimal mitigation scenarios.

Introduction to Defense Acquisition Management

DTIC Science & Technology

1989-03-01

the system after Most new systems follow the same formatted and its usefullness in the weapon inventory predictable life cycle, and fit the model...natives for system concept development Statement (MNS) setting forth requirements need- -An acquisition strategy is developed to guide ed to meet the...6 BUSINESS, FINANCIAL AND TECHNICAL ASPECTS OF SYSTEMS ACQUISITION Management of the systems acquisition process The acquisition planning phase of the

Application of life cycle assessment for an evaluation of wastewater treatment and reuse project--case study of Xi'an, China.

PubMed

Zhang, Q H; Wang, X C; Xiong, J Q; Chen, R; Cao, B

2010-03-01

In order to illuminate the benefit of a wastewater treatment and reuse project, a life cycle assessment (LCA) model was proposed by combining the process-based LCA and the input-output based LCA in one framework and using energy consumption as the sole parameter for quantitative evaluation of the project. The life cycle consumption was evaluated mainly by life cycle inventory (LCI) analysis taking into account the construction phase, operation phase and demolishment phase of the project. For evaluating the life cycle benefit of treated water reuse, attention was paid to the decrease of secondary effluent discharge and water saving. As a result of comprehensive LCA analysis of a case project in Xi'an, China, it was understood that the life cycle benefit gained from treated wastewater reuse much surpassed the life cycle energy consumption. The advantage of wastewater treatment and reuse was well shown by LCA analysis using the proposed model. 2009 Elsevier Ltd. All rights reserved.

A case study by life cycle assessment

NASA Astrophysics Data System (ADS)

Li, Shuyun

2017-05-01

This article aims to assess the potential environmental impact of an electrical grinder during its life cycle. The Life Cycle Inventory Analysis was conducted based on the Simplified Life Cycle Assessment (SLCA) Drivers that calculated from the Valuation of Social Cost and Simplified Life Cycle Assessment Model (VSSM). The detailed results for LCI can be found under Appendix II. The Life Cycle Impact Assessment was performed based on Eco-indicator 99 method. The analysis results indicated that the major contributor to the environmental impact as it accounts for over 60% overall SLCA output. In which, 60% of the emission resulted from the logistic required for the maintenance activities. This was measured by conducting the hotspot analysis. After performing sensitivity analysis, it is evidenced that changing fuel type results in significant decrease environmental footprint. The environmental benefit can also be seen from the negative output values of the recycling activities. By conducting Life Cycle Assessment analysis, the potential environmental impact of the electrical grinder was investigated.

Grouping nanomaterials to predict their potential to induce pulmonary inflammation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braakhuis, Hedwig M., E-mail: hedwig.braakhuis@rivm.nl; Department of Toxicogenomics, Maastricht University, PO Box 616, 6200 MD Maastricht; Oomen, Agnes G.

The rapidly expanding manufacturing, production and use of nanomaterials have raised concerns for both worker and consumer safety. Various studies have been published in which induction of pulmonary inflammation after inhalation exposure to nanomaterials has been described. Nanomaterials can vary in aspects such as size, shape, charge, crystallinity, chemical composition, and dissolution rate. Currently, efforts are made to increase the knowledge on the characteristics of nanomaterials that can be used to categorise them into hazard groups according to these characteristics. Grouping helps to gather information on nanomaterials in an efficient way with the aim to aid risk assessment. Here, wemore » discuss different ways of grouping nanomaterials for their risk assessment after inhalation. Since the relation between single intrinsic particle characteristics and the severity of pulmonary inflammation is unknown, grouping of nanomaterials by their intrinsic characteristics alone is not sufficient to predict their risk after inhalation. The biokinetics of nanomaterials should be taken into account as that affects the dose present at a target site over time. The parameters determining the kinetic behaviour are not the same as the hazard-determining parameters. Furthermore, characteristics of nanomaterials change in the life-cycle, resulting in human exposure to different forms and doses of these nanomaterials. As information on the biokinetics and in situ characteristics of nanomaterials is essential but often lacking, efforts should be made to include these in testing strategies. Grouping nanomaterials will probably be of the most value to risk assessors when information on intrinsic characteristics, life-cycle, biokinetics and effects are all combined. - Highlights: • Grouping of nanomaterials helps to gather information in an efficient way with the aim to aid risk assessment. • Different ways of grouping nanomaterials for their risk assessment after inhalation are discussed. • Grouping of nanomaterials by their intrinsic characteristics alone is not sufficient to predict their risk after inhalation. • To link physicochemical characteristics of nanomaterials to an effect, information on their biokinetic behaviour is needed. • To be of most value, grouping should combine information on intrinsic characteristics, life-cycle, biokinetics and effects.« less

Integration of artificial intelligence methods and life cycle assessment to predict energy output and environmental impacts of paddy production.

PubMed

Nabavi-Pelesaraei, Ashkan; Rafiee, Shahin; Mohtasebi, Seyed Saeid; Hosseinzadeh-Bandbafha, Homa; Chau, Kwok-Wing

2018-08-01

Prediction of agricultural energy output and environmental impacts play important role in energy management and conservation of environment as it can help us to evaluate agricultural energy efficiency, conduct crops production system commissioning, and detect and diagnose faults of crop production system. Agricultural energy output and environmental impacts can be readily predicted by artificial intelligence (AI), owing to the ease of use and adaptability to seek optimal solutions in a rapid manner as well as the use of historical data to predict future agricultural energy use pattern under constraints. This paper conducts energy output and environmental impact prediction of paddy production in Guilan province, Iran based on two AI methods, artificial neural networks (ANNs), and adaptive neuro fuzzy inference system (ANFIS). The amounts of energy input and output are 51,585.61MJkg -1 and 66,112.94MJkg -1 , respectively, in paddy production. Life Cycle Assessment (LCA) is used to evaluate environmental impacts of paddy production. Results show that, in paddy production, in-farm emission is a hotspot in global warming, acidification and eutrophication impact categories. ANN model with 12-6-8-1 structure is selected as the best one for predicting energy output. The correlation coefficient (R) varies from 0.524 to 0.999 in training for energy input and environmental impacts in ANN models. ANFIS model is developed based on a hybrid learning algorithm, with R for predicting output energy being 0.860 and, for environmental impacts, varying from 0.944 to 0.997. Results indicate that the multi-level ANFIS is a useful tool to managers for large-scale planning in forecasting energy output and environmental indices of agricultural production systems owing to its higher speed of computation processes compared to ANN model, despite ANN's higher accuracy. Copyright © 2018 Elsevier B.V. All rights reserved.

Development and validation of cryogenic foam insulation for LH2 subsonic transports

NASA Technical Reports Server (NTRS)

Anthony, F. M.; Colt, J. Z.; Helenbrook, R. G.

1981-01-01

Fourteen foam insulation specimens were tested. Some were plain foam while others contained flame retardants, chopped fiberglass reinforcement and/or vapor barriers. The thermal performance of the insulation was determined by measuring the rate at which LH2 boiled from an aluminum tank insulated with the test material. The test specimens were approximately 50 mm (2 in.) thick. They were structurally scaled so that the test cycle would duplicate the maximum thermal stresses predicted for the thicker insulation of an aircraft liquid hydrogen fuel tank during a typical subsonic flight. The simulated flight cycle of approximately 10 minutes duration heated the other insulation surface to 316 K (110 F) and cooled it to 226 K (20 F) while the inner insulation surface remained at liquid hydrogen temperature of 20 K (-423 F). Two urethane foam insulations exceeded the initial life goal of 2400 simulated flight cycles and sustained 4400 cycles with only minor damage. The addition of fiberglass reinforcement of flame retardant materials to an insulation degraded thermal performance and/or the life of the foam material. Installation of vapor barriers enhanced the structural integrity of the material but did not improve thermal performance. All of the foams tested were available materials; none were developed specifically for LH2 service.

The circle of life: A cross-cultural comparison of children's attribution of life-cycle traits.

PubMed

Burdett, Emily R R; Barrett, Justin L

2016-06-01

Do children attribute mortality and other life-cycle traits to all minded beings? The present study examined whether culture influences young children's ability to conceptualize and differentiate human beings from supernatural beings (such as God) in terms of life-cycle traits. Three-to-5-year-old Israeli and British children were questioned whether their mother, a friend, and God would be subject to various life-cycle processes: Birth, death, ageing, existence/longevity, and parentage. Children did not anthropomorphize but differentiated among human and supernatural beings, attributing life-cycle traits to humans, but not to God. Although 3-year-olds differentiated significantly among agents, 5-year-olds attributed correct life-cycle traits more consistently than younger children. The results also indicated some cross-cultural variation in these attributions. Implications for biological conceptual development are discussed. © 2015 The British Psychological Society.

Long life nickel electrodes for a nickel-hydrogen cell: Cycle life tests

NASA Technical Reports Server (NTRS)

Lim, H. S.; Verzwyvelt, S. A.

1985-01-01

In order to develop a long life nickel electrode for a Ni/H2 cell, the cycle life of nickel electrodes was tested in Ni/H2 boiler plate cells. A 19 test cell matrix was made of various nickel electrode designs including three levels each of plaque mechanical strength, median pore size of the plaque, and active material loading. Test cells were cycled to the end of their life (0.5v) in a 45 minute low Earth orbit cycle regime at 80% depth-of-discharge. It is shown that the active material loading level affects the cycle life the most with the optimum loading at 1.6 g/cc void. Mechanical strength does not affect the cycle life noticeably in the bend strength range of 400 to 700 psi. It is found that the best plaque is made of INCO nickel powder type 287 and has median pore size of 13 micron.

Tropospheric Chemistry

NASA Technical Reports Server (NTRS)

Mohnen, V.

1984-01-01

The fundamental processes that control the chemical composition and cycles of the global troposphere and how these processes and properties affect the physical behavior of the atmosphere are examined. The long-term information needs for tropospheric chemistry are: to be able to predict tropospheric responses to perturbations, both natural and anthropogenic, of these cycles, and to provide the information required for the maintenance and effective future management of the atmospheric component of our global life support system. The processes controlling global tropospheric biogeochemical cycles include: the input of trace species into the troposphere, their long-range transport and distribution as affected by the mean wind and vertical venting, their chemical transformations, including gas to particle conversion, leading to the appearance of aerosols or aqueous phase reactions inside cloud droplets, and their removal from the troposphere via wet (precipitation) and dry deposition.

Large-displacement structural durability analyses of simple bend specimen emulating rocket nozzle liners

NASA Technical Reports Server (NTRS)

Arya, Vinod K.; Halford, Gary R.

1994-01-01

Large-displacement elastic and elastic-plastic, finite-element stress-strain analyses of an oxygen-tree high-conductivity (OFHC) copper plate specimen were performed using an updated Lagrangian formulation. The plate specimen is intended for low-cost experiments that emulate the most important thermomechanical loading and failure modes of a more complex rocket nozzle. The plate, which is loaded in bending at 593 C, contains a centrally located and internally pressurized channel. The cyclic crack initiation lives were estimated using the results from the analyses and isothermal strain-controlled low-cycle fatigue data for OFHC copper. A comparison of the predicted and experimental cyclic lives showed that an elastic analysis predicts a longer cyclic life than that observed in experiments by a factor greater than 4. The results from elastic-plastic analysis for the plate bend specimen, however, predicted a cyclic life in close agreement with experiment, thus justifying the need for the more rigorous stress-strain analysis.

Sociodemographic and psychosocial factors in childhood as predictors of adult mortality.

PubMed Central

Schwartz, J E; Friedman, H S; Tucker, J S; Tomlinson-Keasey, C; Wingard, D L; Criqui, M H

1995-01-01

OBJECTIVES: Childhood sociodemographic, psychosocial, and environmental factors are often assumed to affect adult health and longevity. These relationships were prospectively tested by using the 7-decade Terman Life Cycle Study of Children With High Ability (n = 1285). METHODS: Parental socioeconomic status, childhood health, objective childhood stressors (e.g., death or divorce of parents), and childhood personality were considered as potential predictors in hazard regression analyses of longevity through 1991. RESULTS: Parental divorce during childhood predicted decreased longevity, with sex controlled. Other potential social predictors failed to show significant associations with longevity. Three dimensions of childhood personality--conscientiousness, lack of cheerfulness, and permanency of mood (males only)--predicted increased longevity. The effects of parental divorce and childhood personality were largely independent and did not account for any of the gender difference in mortality. CONCLUSIONS: A small number of childhood factors significantly predicted mortality across the life span in this sample. Further research should focus on how these psychosocial factors influence longevity. PMID:7661231

A vision for an ultra-high resolution integrated water cycle observation and prediction system

NASA Astrophysics Data System (ADS)

Houser, P. R.

2013-05-01

Society's welfare, progress, and sustainable economic growth—and life itself—depend on the abundance and vigorous cycling and replenishing of water throughout the global environment. The water cycle operates on a continuum of time and space scales and exchanges large amounts of energy as water undergoes phase changes and is moved from one part of the Earth system to another. We must move toward an integrated observation and prediction paradigm that addresses broad local-to-global science and application issues by realizing synergies associated with multiple, coordinated observations and prediction systems. A central challenge of a future water and energy cycle observation strategy is to progress from single variable water-cycle instruments to multivariable integrated instruments in electromagnetic-band families. The microwave range in the electromagnetic spectrum is ideally suited for sensing the state and abundance of water because of water's dielectric properties. Eventually, a dedicated high-resolution water-cycle microwave-based satellite mission may be possible based on large-aperture antenna technology that can harvest the synergy that would be afforded by simultaneous multichannel active and passive microwave measurements. A partial demonstration of these ideas can even be realized with existing microwave satellite observations to support advanced multivariate retrieval methods that can exploit the totality of the microwave spectral information. The simultaneous multichannel active and passive microwave retrieval would allow improved-accuracy retrievals that are not possible with isolated measurements. Furthermore, the simultaneous monitoring of several of the land, atmospheric, oceanic, and cryospheric states brings synergies that will substantially enhance understanding of the global water and energy cycle as a system. The multichannel approach also affords advantages to some constituent retrievals—for instance, simultaneous retrieval of vegetation biomass would improve soil-moisture retrieval by avoiding the need for auxiliary vegetation information. This multivariable water-cycle observation system must be integrated with high-resolution, application relevant prediction systems to optimize their information content and utility is addressing critical water cycle issues. One such vision is a real-time ultra-high resolution locally-moasiced global land modeling and assimilation system, that overlays regional high-fidelity information over a baseline global land prediction system. Such a system would provide the best possible local information for use in applications, while integrating and sharing information globally for diagnosing larger water cycle variability. In a sense, this would constitute a hydrologic telecommunication system, where the best local in-situ gage, Doppler radar, and weather station can be shared internationally, and integrated in a consistent manner with global observation platforms like the multivariable water cycle mission. To realize such a vision, large issues must be addressed, such as international data sharing policy, model-observation integration approaches that maintain local extremes while achieving global consistency, and methods for establishing error estimates and uncertainty.

Creep-fatigue life prediction for engine hot section materials (isotropic)

NASA Technical Reports Server (NTRS)

Moreno, V.

1982-01-01

The objectives of this program are the investigation of fundamental approaches to high temperature crack initiation life prediction, identification of specific modeling strategies and the development of specific models for component relevant loading conditions. A survey of the hot section material/coating systems used throughout the gas turbine industry is included. Two material/coating systems will be identified for the program. The material/coating system designated as the base system shall be used throughout Tasks 1-12. The alternate material/coating system will be used only in Task 12 for further evaluation of the models developed on the base material. In Task II, candidate life prediction approaches will be screened based on a set of criteria that includes experience of the approaches within the literature, correlation with isothermal data generated on the base material, and judgements relative to the applicability of the approach for the complex cycles to be considered in the option program. The two most promising approaches will be identified. Task 3 further evaluates the best approach using additional base material fatigue testing including verification tests. Task 4 consists of technical, schedular, financial and all other reporting requirements in accordance with the Reports of Work clause.

Increase Return on Investment of Software Development Life Cycle by Managing the Risk - A Case Study

DTIC Science & Technology

2015-04-01

for increasing the return on investment during the Software Development Life Cycle ( SDLC ) through selected quantitative analyses employing both the...defect rate, return on investment (ROI), software development life cycle ( SDLC ) DE FE N SE A C Q U IS IT IO N UN IVERSITY ALU M N I A SSO C IATIO N R...becomes comfortable due to its intricacies and learning cycle. The same may be said with respect to software development life cycle ( SDLC ) management

Investigations of Si Thin Films as Anode of Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Qingliu; Shi, Bing; Bareño, Javier

Amorphous silicon thin films having various thicknesses were investigated as a negative electrode material for lithium-ion batteries. Electrochemical characterization of the 20 nm thick thin silicon film revealed a very low first cycle Coulombic efficiency, which can be attributed to the silicon oxide layer formed on both the surface of the as-deposited Si thin film and the interface between the Si and the substrate. Among the investigated films, the 100 nm Si thin film demonstrated the best performance in terms of first cycle efficiency and cycle life. Observations from scanning electron microscopy demonstrated that the generation of cracks was inevitablemore » in the cycled Si thin films, even as the thickness of the film was as little as 20 nm, which was not predicted by previous modeling work. However, the cycling performance of the 20 and 100 nm silicon thin films was not detrimentally affected by these cracks. The poor capacity retention of the 1 mu m silicon thin film was attributed to the delamination.« less

LIFE CYCLE ASSESSMENT FOR PC BLEND 2 AIRCRAFT RADOME DEPAINTER

EPA Science Inventory

This report describes the life cycle assessment on a potential replacement solvent blend for aircraft radome depainting at the Oklahoma City Air Logistics Center at Tinker Air Force Base. The life cycle assessment is composed of three separate but interrelated components: life cy...

Slow Crack Growth and Fatigue Life Prediction of Ceramic Components Subjected to Variable Load History

NASA Technical Reports Server (NTRS)

Jadaan, Osama

2001-01-01

Present capabilities of the NASA CARES/Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code include probabilistic life prediction of ceramic components subjected to fast fracture, slow crack growth (stress corrosion), and cyclic fatigue failure modes. Currently, this code has the capability to compute the time-dependent reliability of ceramic structures subjected to simple time-dependent loading. For example, in slow crack growth (SCG) type failure conditions CARES/Life can handle the cases of sustained and linearly increasing time-dependent loads, while for cyclic fatigue applications various types of repetitive constant amplitude loads can be accounted for. In real applications applied loads are rarely that simple, but rather vary with time in more complex ways such as, for example, engine start up, shut down, and dynamic and vibrational loads. In addition, when a given component is subjected to transient environmental and or thermal conditions, the material properties also vary with time. The objective of this paper is to demonstrate a methodology capable of predicting the time-dependent reliability of components subjected to transient thermomechanical loads that takes into account the change in material response with time. In this paper, the dominant delayed failure mechanism is assumed to be SCG. This capability has been added to the NASA CARES/Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code, which has also been modified to have the ability of interfacing with commercially available FEA codes executed for transient load histories. An example involving a ceramic exhaust valve subjected to combustion cycle loads is presented to demonstrate the viability of this methodology and the CARES/Life program.

NREL: U.S. Life Cycle Inventory Database - Related Links

Science.gov Websites

) information, LCA tools, research institutes utilizing LCA, labeling initiatives and organizations , international LCA initiatives, LCA online forums. Life Cycle Inventory Data Ecoinvent: Swiss Centre for Life Institute for Environmental Research and Education): The American Center for Life Cycle Assessment SETAC

[Life cycle assessment of energy consumption and greenhouse gas emissions of cellulosic ethanol from corn stover].

PubMed

Tian, Wang; Liao, Cuiping; Li, Li; Zhao, Daiqing

2011-03-01

Life Cycle Assessment (LCA) is the only standardized tool currently used to assess environmental loads of products and processes. The life cycle analysis, as a part of LCA, is a useful and powerful methodology for studying life cycle energy efficiency and life cycle GHG emission. To quantitatively explain the potential of energy saving and greenhouse gas (GHG) emissions reduction of corn stover-based ethanol, we analyzed life cycle energy consumption and GHG emissions of corn stover-based ethanol by the method of life cycle analysis. The processes are dilute acid prehydrolysis and enzymatic hydrolysis. The functional unit was defined as 1 km distance driven by the vehicle. Results indicated: compared with gasoline, the corn stover-based E100 (100% ethanol) and E10 (a blend of 10% ethanol and 90% gasoline by volume) could reduce life cycle fossil energy consumption by 79.63% and 6.25% respectively, as well as GHG emissions by 53.98% and 6.69%; the fossil energy consumed by biomass stage was 68.3% of total fossil energy input, N-fertilizer and diesel were the main factors which contributed 45.78% and 33.26% to biomass stage; electricity production process contributed 42.06% to the net GHG emissions, the improvement of technology might reduce emissions markedly.

The effects of simulated bone loss on the implant-abutment assembly and likelihood of fracture: an in vitro study.

PubMed

Manzoor, Behzad; Suleiman, Mahmood; Palmer, Richard M

2013-01-01

The crestal bone level around a dental implant may influence its strength characteristics by offering protection against mechanical failures. Therefore, the present study investigated the effect of simulated bone loss on modes, loads, and cycles to failure in an in vitro model. Different amounts of bone loss were simulated: 0, 1.5, 3.0, and 4.5 mm from the implant head. Forty narrow-diameter (3.0-mm) implant-abutment assemblies were tested using compressive bending and cyclic fatigue testing. Weibull and accelerated life testing analysis were used to assess reliability and functional life. Statistical analyses were performed using the Fisher-Exact test and the Spearman ranked correlation. Compressive bending tests showed that the level of bone loss influenced the load-bearing capacity of implant-abutment assemblies. Fatigue testing showed that the modes, loads, and cycles to failure had a statistically significant relationship with the level of bone loss. All 16 samples with bone loss of 3.0 mm or more experienced horizontal implant body fractures. In contrast, 14 of 16 samples with 0 and 1.5 mm of bone loss showed abutment and screw fractures. Weibull and accelerated life testing analysis indicated a two-group distribution: the 0- and 1.5-mm bone loss samples had better functional life and reliability than the 3.0- and 4.5-mm samples. Progressive bone loss had a significant effect on modes, loads, and cycles to failure. In addition, bone loss influenced the functional life and reliability of the implant-abutment assemblies. Maintaining crestal bone levels is important in ensuring biomechanical sustainability and predictable long-term function of dental implant assemblies.

Systems-level feedback regulation of cell cycle transitions in Ostreococcus tauri.

PubMed

Kapuy, Orsolya; Vinod, P K; Bánhegyi, Gábor; Novák, Béla

2018-05-01

Ostreococcus tauri is the smallest free-living unicellular organism with one copy of each core cell cycle genes in its genome. There is a growing interest in this green algae due to its evolutionary origin. Since O. tauri is diverged early in the green lineage, relatively close to the ancestral eukaryotic cell, it might hold a key phylogenetic position in the eukaryotic tree of life. In this study, we focus on the regulatory network of its cell division cycle. We propose a mathematical modelling framework to integrate the existing knowledge of cell cycle network of O. tauri. We observe that feedback loop regulation of both G1/S and G2/M transitions in O. tauri is conserved, which can make the transition bistable. This is essential to make the transition irreversible as shown in other eukaryotic organisms. By performing sequence analysis, we also predict the presence of the Greatwall/PP2A pathway in the cell cycle of O. tauri. Since O. tauri cell cycle machinery is conserved, the exploration of the dynamical characteristic of the cell division cycle will help in further understanding the regulation of cell cycle in higher eukaryotes. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Habitat-based constraints on food web structure and parasite life cycles.

PubMed

Rossiter, Wayne; Sukhdeo, Michael V K

2014-04-01

Habitat is frequently implicated as a powerful determinant of community structure and species distributions, but few studies explicitly evaluate the relationship between habitat-based patterns of species' distributions and the presence or absence of trophic interactions. The complex (multi-host) life cycles of parasites are directly affected by these factors, but almost no data exist on the role of habitat in constraining parasite-host interactions at the community level. In this study the relationship(s) between species abundances, distributions and trophic interactions (including parasitism) were evaluated in the context of habitat structure (classic geomorphic designations of pools, riffles and runs) in a riverine community (Raritan River, Hunterdon County, NJ, USA). We report 121 taxa collected over a 2-year period, and compare the observed food web patterns to null model expectations. The results show that top predators are constrained to particular habitat types, and that species' distributions are biased towards pool habitats. However, our null model (which incorporates cascade model assumptions) accurately predicts the observed patterns of trophic interactions. Thus, habitat strongly dictates species distributions, and patterns of trophic interactions arise as a consequence of these distributions. Additionally, we find that hosts utilized in parasite life cycles are more overlapping in their distributions, and this pattern is more pronounced among those involved in trophic transmission. We conclude that habitat structure may be a strong predictor of parasite transmission routes, particularly within communities that occupy heterogeneous habitats.

KOH concentration effect on the cycle life of nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Lim, H. S.; Verzwyvelt, S. A.

1985-01-01

Effects of KOH concentration on the cycle life of a sintered-type nickel electrode were studied in a boiler plate nickel-hydrogen cell at 23 C using an accelerated 45-min cycle regime at 80 percent depth of discharge. The cycle life improved greatly as the KOH concentration decreased, although the initial capacity of the cell decreased slightly. The cycle life improved by a factor of two or more when the KOH concentration was reduced from 36 to 31 percent and by a similar factor from reductions of 31 to 26 percent. For many applications, this life improvement may outweigh the initial capacity decrease.

Economics of solar energy: Short term costing

NASA Astrophysics Data System (ADS)

Klee, H.

The solar economics based on life cycle costs are refuted as both imaginary and irrelevant. It is argued that predicting rates of inflation and fuel escalation, expected life, maintenance costs, and legislation over the next ten to twenty years is pure guesswork. Furthermore, given the high mobility level of the U.S. population, the average consumer is skeptical of long run arguments which will pay returns only to the next owners. In the short term cost analysis, the house is sold prior to the end of the expected life of the system. The cash flow of the seller and buyer are considered. All the relevant factors, including the federal tax credit and the added value of the house because of the solar system are included.

Effects of shortened host life span on the evolution of parasite life history and virulence in a microbial host-parasite system

PubMed Central

Nidelet, Thibault; Koella, Jacob C; Kaltz, Oliver

2009-01-01

Background Ecological factors play an important role in the evolution of parasite exploitation strategies. A common prediction is that, as shorter host life span reduces future opportunities of transmission, parasites compensate with an evolutionary shift towards earlier transmission. They may grow more rapidly within the host, have a shorter latency time and, consequently, be more virulent. Thus, increased extrinsic (i.e., not caused by the parasite) host mortality leads to the evolution of more virulent parasites. To test these predictions, we performed a serial transfer experiment, using the protozoan Paramecium caudatum and its bacterial parasite Holospora undulata. We simulated variation in host life span by killing hosts after 11 (early killing) or 14 (late killing) days post inoculation; after killing, parasite transmission stages were collected and used for a new infection cycle. Results After 13 cycles (≈ 300 generations), parasites from the early-killing treatment were less infectious, but had shorter latency time and higher virulence than those from the late-killing treatment. Overall, shorter latency time was associated with higher parasite loads and thus presumably with more rapid within-host replication. Conclusion The analysis of the means of the two treatments is thus consistent with theory, and suggests that evolution is constrained by trade-offs between virulence, transmission and within-host growth. In contrast, we found little evidence for such trade-offs across parasite selection lines within treatments; thus, to some extent, these traits may evolve independently. This study illustrates how environmental variation (experienced by the host) can lead to the evolution of distinct parasite strategies. PMID:19320981

Effect of LEO cycling on 125 Ah advanced design IPV nickel-hydrogen flight cells - An update

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

Evaluation of life-cycle air emission factors of freight transportation.

PubMed

Facanha, Cristiano; Horvath, Arpad

2007-10-15

Life-cycle air emission factors associated with road, rail, and air transportation of freight in the United States are analyzed. All life-cycle phases of vehicles, infrastructure, and fuels are accounted for in a hybrid life-cycle assessment (LCA). It includes not only fuel combustion, but also emissions from vehicle manufacturing, maintenance, and end of life, infrastructure construction, operation, maintenance, and end of life, and petroleum exploration, refining, and fuel distribution. Results indicate that total life-cycle emissions of freight transportation modes are underestimated if only tailpipe emissions are accounted for. In the case of CO2 and NOx, tailpipe emissions underestimate total emissions by up to 38%, depending on the mode. Total life-cycle emissions of CO and SO2 are up to seven times higher than tailpipe emissions. Sensitivity analysis considers the effects of vehicle type, geography, and mode efficiency on the final results. Policy implications of this analysis are also discussed. For example, while it is widely assumed that currently proposed regulations will result in substantial reductions in emissions, we find that this is true for NOx, emissions, because fuel combustion is the main cause, and to a lesser extent for SO2, but not for PM10 emissions, which are significantly affected by the other life-cycle phases.

Comparative Life Cycle Assessment between Warm SMA and Conventional SMA

DOT National Transportation Integrated Search

2011-09-01

This report presents the comparative life cycle assessment (LCA) between warm stone mastic asphalt (SMA) and conventional : SMA. Specifically, the study evaluated and compared the life cycle environmental and economic performances of two mixtures: a ...

Challenges in predicting climate and environmental effects on vector-borne disease episystems in a changing world.

PubMed

Tabachnick, W J

2010-03-15

Vector-borne pathogens cause enormous suffering to humans and animals. Many are expanding their range into new areas. Dengue, West Nile and Chikungunya have recently caused substantial human epidemics. Arthropod-borne animal diseases like Bluetongue, Rift Valley fever and African horse sickness pose substantial threats to livestock economies around the world. Climate change can impact the vector-borne disease epidemiology. Changes in climate will influence arthropod vectors, their life cycles and life histories, resulting in changes in both vector and pathogen distribution and changes in the ability of arthropods to transmit pathogens. Climate can affect the way pathogens interact with both the arthropod vector and the human or animal host. Predicting and mitigating the effects of future changes in the environment like climate change on the complex arthropod-pathogen-host epidemiological cycle requires understanding of a variety of complex mechanisms from the molecular to the population level. Although there has been substantial progress on many fronts the challenges to effectively understand and mitigate the impact of potential changes in the environment on vector-borne pathogens are formidable and at an early stage of development. The challenges will be explored using several arthropod-borne pathogen systems as illustration, and potential avenues to meet the challenges will be presented.

Movement Complexity and Neuromechanical Factors Affect the Entropic Half-Life of Myoelectric Signals

PubMed Central

Hodson-Tole, Emma F.; Wakeling, James M.

2017-01-01

Appropriate neuromuscular functioning is essential for survival and features underpinning motor control are present in myoelectric signals recorded from skeletal muscles. One approach to quantify control processes related to function is to assess signal variability using measures such as Sample Entropy. Here we developed a theoretical framework to simulate the effect of variability in burst duration, activation duty cycle, and intensity on the Entropic Half-Life (EnHL) in myoelectric signals. EnHLs were predicted to be <40 ms, and to vary with fluctuations in myoelectric signal amplitude and activation duty cycle. Comparison with myoelectic data from rats walking and running at a range of speeds and inclines confirmed the range of EnHLs, however, the direction of EnHL change in response to altered locomotor demand was not correctly predicted. The discrepancy reflected different associations between the ratio of the standard deviation and mean signal intensity (Ist:It¯) and duty factor in simulated and physiological data, likely reflecting additional information in the signals from the physiological data (e.g., quiescent phase content; variation in action potential shapes). EnHL could have significant value as a novel marker of neuromuscular responses to alterations in perceived locomotor task complexity and intensity. PMID:28974932

Geothermal Water Use: Life Cycle Water Consumption, Water Resource Assessment, and Water Policy Framework

DOE Data Explorer

Schroeder, Jenna N.

2014-06-10

This report examines life cycle water consumption for various geothermal technologies to better understand factors that affect water consumption across the life cycle (e.g., power plant cooling, belowground fluid losses) and to assess the potential water challenges that future geothermal power generation projects may face. Previous reports in this series quantified the life cycle freshwater requirements of geothermal power-generating systems, explored operational and environmental concerns related to the geochemical composition of geothermal fluids, and assessed future water demand by geothermal power plants according to growth projections for the industry. This report seeks to extend those analyses by including EGS flash, both as part of the life cycle analysis and water resource assessment. A regional water resource assessment based upon the life cycle results is also presented. Finally, the legal framework of water with respect to geothermal resources in the states with active geothermal development is also analyzed.

Long Life Nickel Electrodes for a Nickel-hydrogen Cell: Cycle Life Tests

NASA Technical Reports Server (NTRS)

Lim, H. S.; Verzwyvelt, S. A.

1984-01-01

In order to develop a long life nickel electrode for a Ni/H2 cell, cycle life tests of nickel electrodes were carried out in Hi/H2 boiler plate cells. A 19 test cell matrix was made of various nickel electrode designs including three levels each of plaque mechanical strength, median pore size of the plaque, and active material loading. Test cells were cycled to the end of their life (0.5v) in a 45-minute low earth orbit cycle regime at 80% depth-of-discharge. The results show that the active material loading level affects the cycle life the most with the optimum loading at 1.6 g/cc void. Mechanical strength did not affect the cycle life noticeably in the bend strength range of 400 to 700 psi. The best plaque type appears to be one which is made of INCO nickel powder type 287 and has a median pore size of 13 micron.

A comparative study of commercial lithium ion battery cycle life in electric vehicle: Capacity loss estimation

NASA Astrophysics Data System (ADS)

Han, Xuebing; Ouyang, Minggao; Lu, Languang; Li, Jianqiu

2014-12-01

Now the lithium ion batteries are widely used in electric vehicles (EV). The cycle life is among the most important characteristics of the power battery in EV. In this report, the battery cycle life experiment is designed according to the actual working condition in EV. Five different commercial lithium ion cells are cycled alternatively under 45 °C and 5 °C and the test results are compared. Based on the cycle life experiment results and the identified battery aging mechanism, the battery cycle life models are built and fitted by the genetic algorithm. The capacity loss follows a power law relation with the cycle times and an Arrhenius law relation with the temperature. For automotive application, to save the cost and the testing time, a battery SOH (state of health) estimation method combined the on-line model based capacity estimation and regular calibration is proposed.

A Growth Model for Academic Program Life Cycle (APLC): A Theoretical and Empirical Analysis

ERIC Educational Resources Information Center

Acquah, Edward H. K.

2010-01-01

Academic program life cycle concept states each program's life flows through several stages: introduction, growth, maturity, and decline. A mixed-influence diffusion growth model is fitted to enrolment data on academic programs to analyze the factors determining progress of academic programs through their life cycles. The regression analysis yield…

A Life Cycle Cost Analysis of Rigid Pavements

DOT National Transportation Integrated Search

1999-09-01

The Texas Department of Transportation (TxDOT)commissioned a research project in 1996, summarized here, to promote life cycle cost analysis of rigid pavements throughout the TxDOT districts by developing a uniform methodology for performing life cycl...

Intersection life cycle cost comparison tool user guide version 1.0.

DOT National Transportation Integrated Search

2016-05-01

The Intersection Life Cycle Cost Comparison Tool User Guide was developed as part of North : Carolina Department of Transportation Research Project No. 201411: Evaluation of Life Cycle : Impacts of Intersection Control Type Selection. : This sprea...

Life Cycle Impact Assessment Research Developments and Needs

EPA Science Inventory

Life Cycle Impact Assessment (LCIA) developments are explained along with key publications which record discussions which comprised ISO 14042 and SETAC document development, UNEP SETAC Life Cycle Initiative research, and research from public and private research institutions. It ...

Does the Current Minimum Validate (or Invalidate) Cycle Prediction Methods?

NASA Technical Reports Server (NTRS)

Hathaway, David H.

2010-01-01

This deep, extended solar minimum and the slow start to Cycle 24 strongly suggest that Cycle 24 will be a small cycle. A wide array of solar cycle prediction techniques have been applied to predicting the amplitude of Cycle 24 with widely different results. Current conditions and new observations indicate that some highly regarded techniques now appear to have doubtful utility. Geomagnetic precursors have been reliable in the past and can be tested with 12 cycles of data. Of the three primary geomagnetic precursors only one (the minimum level of geomagnetic activity) suggests a small cycle. The Sun's polar field strength has also been used to successfully predict the last three cycles. The current weak polar fields are indicative of a small cycle. For the first time, dynamo models have been used to predict the size of a solar cycle but with opposite predictions depending on the model and the data assimilation. However, new measurements of the surface meridional flow indicate that the flow was substantially faster on the approach to Cycle 24 minimum than at Cycle 23 minimum. In both dynamo predictions a faster meridional flow should have given a shorter cycle 23 with stronger polar fields. This suggests that these dynamo models are not yet ready for solar cycle prediction.

Application of Pharmacokinetics and Pharmacodynamics in Product Life Cycle Management. A Case Study with a Carbidopa-Levodopa Extended-Release Formulation.

PubMed

Modi, Nishit B

2017-05-01

Increasing costs in discovering and developing new molecular entities and the continuing debate on limited company pipelines mean that pharmaceutical companies are under significant pressure to maximize the value of approved products. Life cycle management in the context of drug development comprises activities to maximize the effective life of a product. Life cycle approaches can involve new formulations, new routes of delivery, new indications or expansion of the population for whom the product is indicated, or development of combination products. Life cycle management may provide an opportunity to improve upon the current product through enhanced efficacy or reduced side effects and could expand the therapeutic market for the product. Successful life cycle management may include the potential for superior efficacy, improved tolerability, or a better prescriber or patient acceptance. Unlike generic products where bioequivalence to an innovator product may be sufficient for drug approval, life cycle management typically requires a series of studies to characterize the value of the product. This review summarizes key considerations in identifying product candidates that may be suitable for life cycle management and discusses the application of pharmacokinetics and pharmacodynamics in developing new products using a life cycle management approach. Examples and a case study to illustrate how pharmacokinetics and pharmacodynamics contributed to the selection of dosing regimens, demonstration of an improved therapeutic effect, or regulatory approval of an improved product label are presented.

Building Maintenance and Repair Data for Life-Cycle Cost Analyses: Electrical Systems.

DTIC Science & Technology

1991-05-01

Repair Data for Life-Cycle Cost Analyses: Electrical Systems by Edgar S. Neely Robert D. Neathammer James R. Stirn Robert P. Winkler This research...systems have been developed to assist planners in preparing DD Form 1391 documentation, designers in life-cycle cost component selection, and maintainers...Maintenance and Repair Data for Life-Cycle Cost Analyses: RDTE dated 1980 Electrical Systems REIMB 1984 - 1989 6. AUTH4OR(S) Edgar S. Neely, Robert D

Why Army Program Managers Struggle As Life Cycle Managers: A Study of the PM’s Roles, Responsibilities, and Barriers In the Execution of Operations and Support

DTIC Science & Technology

2016-09-01

Support Strategies (PBPSS), throughout the system life cycle .  Maximizing competition, to include small business participation.  Developing...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA JOINT APPLIED PROJECT WHY ARMY PROGRAM MANAGERS STRUGGLE AS LIFE CYCLE MANAGERS...SUBTITLE WHY ARMY PROGRAM MANAGERS STRUGGLE AS LIFE CYCLE MANAGERS: A STUDY OF THE PM’S ROLES, RESPONSIBILITIES, AND BARRIERS IN THE EXECUTION OF

Technical Consultation of the Hubble Space Telescope (HST) Nickel Hydrogen (NiH2) Battery Charge Capacity Prediction. Version 1.0

NASA Technical Reports Server (NTRS)

Gentz, Steven J.; Pandipati, Radha; Ling, Jerri; Miller, Thomas; Jeevarajan, Judith; Halpert, Gerald; Zimmerman, Albert

2005-01-01

The purpose of the GSFC position paper is to identify critical HST milestone dates for continued science studies followed by the attachment of a re-entry module or a robotic servicing mission. The paper examines the viability of the HST with respect to the NiH2 continued battery charge capacity. In the course of the assessment, it was recognized that the HST battery thermal control system has an average heat dissipation limitation of 30 W per bay per orbit cycle. This thermal constraint will continue to govern options for battery capacity maintenance. In addition, the HST usage represents the longest exposure ofNiH2 batteries to Low Earth Orbit (LEO) at the current level of Depth of Discharge (DOD). Finally, the current battery life is at the limit predicted by the manufacturer, Eaglepicher. Therefore, given these factors, the potential exists that the HST battery capacities could radically degrade at any point. Given this caveat on any life extrapolations, the conservative model proposed in the GSFC position paper was viewed by the NESC as having several technical assumptions such as limited utilization of flight battery capacity data, the susceptibility of the proposed prediction method to large variations when supplemented with additional information, and the failure to qualitatively or quantitatively assess life prediction sensitivities. The NESC conducted an independent evaluation of the supporting information and assumptions to generate the predictions for battery capacity loss and practicality of on-orbit battery conditioning.

Evolutionary lability of a complex life cycle in the aphid genus Brachycaudus.

PubMed

Emmanuelle, Jousselin; Gwenaelle, Genson; Armelle, Coeur d'acier

2010-09-28

Most aphid species complete their life cycle on the same set of host-plant species, but some (heteroecious species) alternate between different hosts, migrating from primary (woody) to secondary (herbaceous) host plants. The evolutionary processes behind the evolution of this complex life cycle have often been debated. One widely accepted scenario is that heteroecy evolved from monoecy on woody host plants. Several shifts towards monoecy on herbaceous plants have subsequently occurred and resulted in the radiation of aphids. Host alternation would have persisted in some cases due to developmental constraints preventing aphids from shifting their entire life cycle to herbaceous hosts (which are thought to be more favourable). According to this scenario, if aphids lose their primary host during evolution they should not regain it. The genus Brachycaudus includes species with all the types of life cycle (monoecy on woody plants, heteroecy, monoecy on herbs). We used this genus to test hypotheses concerning the evolution of life cycles in aphids. Phylogenetic investigation and character reconstruction suggest that life cycle is evolutionary labile in the genus. Though ancestral character states can be ambiguous depending on optimization methods, all analyses suggest that transitions from monoecy on herbs towards heteroecy have occurred several times. Transitions from heteroecy towards monoecy, are also likely. There have been many shifts in feeding behaviour but we found no significant correlation between life cycle changes and changes in diet. The transitions from monoecy on herbs towards heteroecy observed in this study go against a widely accepted evolutionary scenario: aphids in the genus Brachycaudus seem to be able to recapture their supposedly ancestral woody host. This suggests that the determinants of host alternation are probably not as complicated as previously thought. Definitive proofs of the lability of life cycle in Brachycaudus will necessitate investigation of these determinants. Life cycle changes, whether corresponding to the loss or acquisition of a primary host, necessarily promote speciation, by inducing shifts of the reproductive phase on different plants. We suggest that the evolutionary lability of life cycle may have driven speciation events in the Brachycaudus genus.

Enhancing fatigue life of cylinder-crown integrated structure by optimizing dimension

NASA Astrophysics Data System (ADS)

Zhang, Weiwei; Wang, Xiaosong; Wang, Zhongren; Yuan, Shijian

2015-03-01

Cylinder-crown integrated hydraulic press (CCIHP) is a new press structure. The hemispherical hydraulic cylinder also functions as a main portion of crown, which has lower weight and higher section modulus compared with the conventional hydraulic cylinder and press crown. As a result, the material strength capacity is better utilized. During the engineering design of cylinder-crown integrated structure, in order to increase the fatigue life, structural optimization on the basis of the adaptive macro genetic algorithms (AMGA) is first conducted to both reduce weight and decrease peak stress. It is shown that the magnitude of the maximum principal stress is decreased by 28.6%, and simultaneously the total weight is reduced by 4.4%. Subsequently, strain-controlled fatigue test is carried out, and the stress-strain hysteresis loops and cyclic hardening curve are obtained. Based on linear fit, the fatigue properties are calculated and used for the fatigue life prediction. It is shown that the predicted fatigue life is significantly increased from 157000 to 1070000 cycles after structural optimization. Finally, according to the optimization design, a 6300 kN CCIHP has been manufactured, and priority application has been also suggested.

A Microstructure-Based Time-Dependent Crack Growth Model for Life and Reliability Prediction of Turbopropulsion Systems

NASA Astrophysics Data System (ADS)

Chan, Kwai S.; Enright, Michael P.; Moody, Jonathan; Fitch, Simeon H. K.

2014-01-01

The objective of this investigation was to develop an innovative methodology for life and reliability prediction of hot-section components in advanced turbopropulsion systems. A set of generic microstructure-based time-dependent crack growth (TDCG) models was developed and used to assess the sources of material variability due to microstructure and material parameters such as grain size, activation energy, and crack growth threshold for TDCG. A comparison of model predictions and experimental data obtained in air and in vacuum suggests that oxidation is responsible for higher crack growth rates at high temperatures, low frequencies, and long dwell times, but oxidation can also induce higher crack growth thresholds (Δ K th or K th) under certain conditions. Using the enhanced risk analysis tool and material constants calibrated to IN 718 data, the effect of TDCG on the risk of fracture in turboengine components was demonstrated for a generic rotor design and a realistic mission profile using the DARWIN® probabilistic life-prediction code. The results of this investigation confirmed that TDCG and cycle-dependent crack growth in IN 718 can be treated by a simple summation of the crack increments over a mission. For the temperatures considered, TDCG in IN 718 can be considered as a K-controlled or a diffusion-controlled oxidation-induced degradation process. This methodology provides a pathway for evaluating microstructural effects on multiple damage modes in hot-section components.

An Overview of Different Approaches for Battery Lifetime Prediction

NASA Astrophysics Data System (ADS)

Zhang, Peng; Liang, Jun; Zhang, Feng

2017-05-01

With the rapid development of renewable energy and the continuous improvement of the power supply reliability, battery energy storage technology has been wildly used in power system. Battery degradation is a nonnegligible issue when battery energy storage system participates in system design and operation strategies optimization. The health assessment and remaining cycle life estimation of battery gradually become a challenge and research hotspot in many engineering areas. In this paper, the battery capacity falling and internal resistance increase are presented on the basis of chemical reactions inside the battery. The general life prediction models are analysed from several aspects. The characteristics of them as well as their application scenarios are discussed in the survey. In addition, a novel weighted Ah ageing model with the introduction of the Ragone curve is proposed to provide a detailed understanding of the ageing processes. A rigorous proof of the mathematical theory about the proposed model is given in the paper.

Performance Evaluation and Modeling of Erosion Resistant Turbine Engine Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Miller, Robert A.; Zhu, Dongming; Kuczmarski, Maria

2008-01-01

The erosion resistant turbine thermal barrier coating system is critical to the rotorcraft engine performance and durability. The objective of this work was to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and thermal gradient environments, thus validating a new thermal barrier coating turbine blade technology for future rotorcraft applications. A high velocity burner rig based erosion test approach was established and a new series of rare earth oxide- and TiO2/Ta2O5- alloyed, ZrO2-based low conductivity thermal barrier coatings were designed and processed. The low conductivity thermal barrier coating systems demonstrated significant improvements in the erosion resistance. A comprehensive model based on accumulated strain damage low cycle fatigue is formulated for blade erosion life prediction. The work is currently aiming at the simulated engine erosion testing of advanced thermal barrier coated turbine blades to establish and validate the coating life prediction models.

5 CFR 930.301 - Information systems security awareness training program.

Code of Federal Regulations, 2012 CFR

2012-01-01

... training in system/application life cycle management, risk management, and contingency planning. (4) Chief... security management, system/application life cycle management, risk management, and contingency planning... management; and management and implementation level training in system/application life cycle management...

Life Cycle Assessment for Biofuels

EPA Science Inventory

A presentation based on life cycle assessment (LCA) for biofuels is given. The presentation focuses on energy and biofuels, interesting environmental aspects of biofuels, and how to do a life cycle assessment with some examples related to biofuel systems. The stages of a (biofuel...

Data Base Development of Automobile and Light Truck Maintenance : Volume II. Appendix E.

DOT National Transportation Integrated Search

1978-08-01

The document contains the scheduled maintenance data sheets and total cost summaries--both scheduled and unscheduled maintenance (Life cycle cost for Dealers, life cycle cost for Service Stations, life cycle cost for Independent Repair, and scheduled...

Data Base Development of Automobile and Light Truck Maintenance : Volume III. Appendix F.

DOT National Transportation Integrated Search

1978-08-01

The document contains the scheduled maintenance data sheets and total cost summaries--both scheduled and unscheduled maintenance (Life cycle cost for Dealers, life cycle cost for Service Stations, life cycle cost for Independent Repair, and scheduled...

LIFE CYCLE ASSESSMENT: PRINCIPLES AND PRACTICE

EPA Science Inventory

The following document provides an introductory overview of Life Cycle Assessment (LCA) and describes the general uses and major components of LCA. This document is an update and merger of two previous EPA documents on LCA ("Life Cycle Assessment: Inventory Guidelines and Princip...

Utilizing individual fish biomass and relative abundance models to map environmental niche associations of adult and juvenile targeted fishes.

PubMed

Galaiduk, Ronen; Radford, Ben T; Harvey, Euan S

2018-06-21

Many fishes undergo ontogenetic habitat shifts to meet their energy and resource needs as they grow. Habitat resource partitioning and patterns of habitat connectivity between conspecific fishes at different life-history stages is a significant knowledge gap. Species distribution models were used to examine patterns in the relative abundance, individual biomass estimates and environmental niche associations of different life stages of three iconic West Australian fishes. Continuous predictive maps describing the spatial distribution of abundance and individual biomass of the study species were created as well predictive hotspot maps that identify possible areas for aggregation of individuals of similar life stages of multiple species (i.e. spawning grounds, fisheries refugia or nursery areas). The models and maps indicate that processes driving the abundance patterns could be different from the body size associated demographic processes throughout an individual's life cycle. Incorporating life-history in the spatially explicit management plans can ensure that critical habitat of the vulnerable stages (e.g. juvenile fish, spawning stock) is included within proposed protected areas and can enhance connectivity between various functional areas (e.g. nursery areas and adult populations) which, in turn, can improve the abundance of targeted species as well as other fish species relying on healthy ecosystem functioning.

Model training across multiple breeding cycles significantly improves genomic prediction accuracy in rye (Secale cereale L.).

PubMed

Auinger, Hans-Jürgen; Schönleben, Manfred; Lehermeier, Christina; Schmidt, Malthe; Korzun, Viktor; Geiger, Hartwig H; Piepho, Hans-Peter; Gordillo, Andres; Wilde, Peer; Bauer, Eva; Schön, Chris-Carolin

2016-11-01

Genomic prediction accuracy can be significantly increased by model calibration across multiple breeding cycles as long as selection cycles are connected by common ancestors. In hybrid rye breeding, application of genome-based prediction is expected to increase selection gain because of long selection cycles in population improvement and development of hybrid components. Essentially two prediction scenarios arise: (1) prediction of the genetic value of lines from the same breeding cycle in which model training is performed and (2) prediction of lines from subsequent cycles. It is the latter from which a reduction in cycle length and consequently the strongest impact on selection gain is expected. We empirically investigated genome-based prediction of grain yield, plant height and thousand kernel weight within and across four selection cycles of a hybrid rye breeding program. Prediction performance was assessed using genomic and pedigree-based best linear unbiased prediction (GBLUP and PBLUP). A total of 1040 S 2 lines were genotyped with 16 k SNPs and each year testcrosses of 260 S 2 lines were phenotyped in seven or eight locations. The performance gap between GBLUP and PBLUP increased significantly for all traits when model calibration was performed on aggregated data from several cycles. Prediction accuracies obtained from cross-validation were in the order of 0.70 for all traits when data from all cycles (N CS  = 832) were used for model training and exceeded within-cycle accuracies in all cases. As long as selection cycles are connected by a sufficient number of common ancestors and prediction accuracy has not reached a plateau when increasing sample size, aggregating data from several preceding cycles is recommended for predicting genetic values in subsequent cycles despite decreasing relatedness over time.

Developing a dynamic life cycle greenhouse gas emission inventory for wood construction for two different end-of-life scenarios

Treesearch

Richard D. Bergman; James Salazar; Scott Bowe

2012-01-01

Static life cycle assessment does not fully describe the carbon footprint of construction wood because of carbon changes in the forest and product pools over time. This study developed a dynamic greenhouse gas (GHG) inventory approach using US Forest Service and life-cycle data to estimate GHG emissions on construction wood for two different end-of-life scenarios....

A Methodology for Integrated, Multiregional Life Cycle Assessment Scenarios under Large-Scale Technological Change.

PubMed

Gibon, Thomas; Wood, Richard; Arvesen, Anders; Bergesen, Joseph D; Suh, Sangwon; Hertwich, Edgar G

2015-09-15

Climate change mitigation demands large-scale technological change on a global level and, if successfully implemented, will significantly affect how products and services are produced and consumed. In order to anticipate the life cycle environmental impacts of products under climate mitigation scenarios, we present the modeling framework of an integrated hybrid life cycle assessment model covering nine world regions. Life cycle assessment databases and multiregional input-output tables are adapted using forecasted changes in technology and resources up to 2050 under a 2 °C scenario. We call the result of this modeling "technology hybridized environmental-economic model with integrated scenarios" (THEMIS). As a case study, we apply THEMIS in an integrated environmental assessment of concentrating solar power. Life-cycle greenhouse gas emissions for this plant range from 33 to 95 g CO2 eq./kWh across different world regions in 2010, falling to 30-87 g CO2 eq./kWh in 2050. Using regional life cycle data yields insightful results. More generally, these results also highlight the need for systematic life cycle frameworks that capture the actual consequences and feedback effects of large-scale policies in the long term.

THE COMPONENTS OF KIN COMPETITION

PubMed Central

Van Dyken, J. David

2011-01-01

It is well known that competition among kin alters the rate and often the direction of evolution in subdivided populations. Yet much remains unclear about the ecological and demographic causes of kin competition, or what role life cycle plays in promoting or ameliorating its effects. Using the multilevel Price equation, I derive a general equation for evolution in structured populations under an arbitrary intensity of kin competition. This equation partitions the effects of selection and demography, and recovers numerous previous models as special cases. I quantify the degree of kin competition, α, which explicitly depends on life cycle. I show how life cycle and demographic assumptions can be incorporated into kin selection models via α, revealing life cycles that are more or less permissive of altruism. As an example, I give closed-form results for Hamilton’s rule in a three-stage life cycle. Although results are sensitive to life cycle in general, I identify three demographic conditions that give life cycle invariant results. Under the infinite island model, α is a function of the scale of density regulation and dispersal rate, effectively disentangling these two phenomena. Population viscosity per se does not impede kin selection. PMID:20482610

Water Cycle Missions for the Next Decade

NASA Astrophysics Data System (ADS)

Houser, P. R.

2013-12-01

The global water cycle describes the circulation of water as a vital and dynamic substance in its liquid, solid, and vapor phases as it moves through the atmosphere, oceans and land. Life in its many forms exists because of water, and modern civilization depends on learning how to live within the constraints imposed by the availability of water. The scientific challenge posed by the need to observe the global water cycle is to integrate in situ and space-borne observations to quantify the key water-cycle state variables and fluxes. The vision to address that challenge is a series of Earth observation missions that will measure the states, stocks, flows, and residence times of water on regional to global scales followed by a series of coordinated missions that will address the processes, on a global scale, that underlie variability and changes in water in all its three phases. The accompanying societal challenge is to foster the improved use of water data and information as a basis for enlightened management of water resources, to protect life and property from effects of extremes in the water cycle. A major change in thinking about water science that goes beyond its physics to include its role in ecosystems and society is also required. Better water-cycle observations, especially on the continental and global scales, will be essential. Water-cycle predictions need to be readily available globally to reduce loss of life and property caused by water-related natural hazards. Building on the 2007 Earth Science Decadal Survey, NASA's Plan for a Climate-Centric Architecture for Earth Observations and Applications from Space , and the 2012 Chapman Conference on Remote Sensing of the Terrestrial Water Cycle, a workshop was held in April 2013 to gather wisdom and determine how to prepare for the next generation of water cycle missions in support of the second Earth Science Decadal Survey. This talk will present the outcomes of the workshop including the intersection between science questions, technology readiness and satellite design optimization. A series of next-generation water cycle mission working groups were proposed and white papers, designed to identify capacity gaps and inform NASA were developed. The workshop identified several visions for the next decade of water cycle satellite observations, and developed a roadmap and action plan for developing the foundation for these missions. Achieving this outcome will result in optimized community investments and better functionality of these future missions, and will help to foster broader range of scientists and professionals engaged in water cycle observation planning and development around the country, and the world.

Persistent carry-over effects of planktonic exposure to ocean acidification in the Olympia oyster.

PubMed

Hettinger, Annaliese; Sanford, Eric; Hill, Tessa M; Russell, Ann D; Sato, Kirk N S; Hoey, Jennifer; Forsch, Margaux; Page, Heather N; Gaylord, Brian

2012-12-01

Predicting impacts of global environmental change is challenging due to the complex life cycles that characterize many terrestrial and aquatic taxa. Different life stages often interact with the physical environment in distinct ways, and a growing body of work suggests that stresses experienced during one life stage can "carry over" to influence subsequent stages. Assessments of population responses to environmental perturbation must therefore consider how effects might propagate across life-history transitions. We investigated consequences of ocean acidification (decreased pH and carbonate saturation) for early life stages of the Olympia oyster (Ostrea lurida), a foundation species in estuaries along the Pacific coast of North America. We reared oysters at three levels of seawater pH, including a control (8.0) and two additional levels (7.9 and 7.8). Oysters were cultured through their planktonic larval period to metamorphosis and into early juvenile life. Larvae reared under pH 7.8 exhibited a 15% decrease in larval shell growth rate, and a 7% decrease in shell area at settlement, compared to larvae reared under control conditions. Impacts were even more pronounced a week after settlement, with juveniles that had been reared as larvae under reduced pH exhibiting a 41% decrease in shell growth rate. Importantly, the latter effect arose regardless of the pH level the oysters experienced as juveniles, indicating a strong carry-over effect from the larval phase. Adverse impacts of early exposure to low pH persisted for at least 1.5 months after juveniles were transferred to a common environment. Overall, our results suggest that a stringent focus on a single phase of the life cycle (e.g., one perceived as the "weakest link") may neglect critical impacts that can be transferred across life stages in taxa with complex life histories.

[Specific manifestations of polyvariant life cycles in ground beetles (Coleoptera, Carabidae) along latitudinal gradient].

PubMed

Matalin, A V

2014-01-01

The life cycles of Carabidae are highly diverse, and 25 variants of these cycles are realized In the European part of Russia, from semideserts to continental tundras. The diversity of the life cycle spectrum sharply decreases (by more than half) upon transition from nemoral to boreal forest communities, and its phenological unification takes place at high latitudes. The greatest proportion of species with polyvariant development (25%) is characteristic of temporal latitudes, which may be explained by relatively long growing season and considerable cenotic diversity. In both southern (semidesert and steppe) and northern regions (middle and northern boreal forests), this proportion does not exceed 5%. At low latitudes, the polyvariant pattern of development is often manifested in the form of facultative bivoltine life cycles or as facultative biennial life cycles in species with the initial "spring" breeding type.

USING LIFE CYCLE ASSESSMENT TOOLS FOR INTEGRATED PRODUCT POLICY

EPA Science Inventory

The European Union's new Integrated Product Policy directs governments and companies to consider the entire product life cycle, from cradle to grave, in their environmental decision-making process. A life-cycle based approach is intended to lead toward true environmental improvem...

41 CFR 109-1.5304 - Deviations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... High Risk Personal Property § 109-1.5304 Deviations. (a) Life cycle control determinations. When the HFO approves a contractor program containing controls, other than life cycle control consistent with... Secretary for Procurement and Assistance Management. A HFO's decision not to provide life-cycle control...

41 CFR 109-1.5304 - Deviations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... High Risk Personal Property § 109-1.5304 Deviations. (a) Life cycle control determinations. When the HFO approves a contractor program containing controls, other than life cycle control consistent with... Secretary for Procurement and Assistance Management. A HFO's decision not to provide life-cycle control...