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Sample records for based life prediction

  1. Life prediction of Ni-base superalloy

    Indian Academy of Sciences (India)

    M Aghaie-Khafri; M Noori

    2011-04-01

    Rene 80 samples were creep–rupture tested in air between 1144 and 1255 K at various stress levels. The mean stress exponent, , and the mean activation energy for creep were calculated from the experimental results. The accelerated creep life of the alloy was evaluated by using iso-stress parametric equations and Monkman–Grant method.

  2. SHM-Based Probabilistic Fatigue Life Prediction for Bridges Based on FE Model Updating.

    Science.gov (United States)

    Lee, Young-Joo; Cho, Soojin

    2016-03-02

    Fatigue life prediction for a bridge should be based on the current condition of the bridge, and various sources of uncertainty, such as material properties, anticipated vehicle loads and environmental conditions, make the prediction very challenging. This paper presents a new approach for probabilistic fatigue life prediction for bridges using finite element (FE) model updating based on structural health monitoring (SHM) data. Recently, various types of SHM systems have been used to monitor and evaluate the long-term structural performance of bridges. For example, SHM data can be used to estimate the degradation of an in-service bridge, which makes it possible to update the initial FE model. The proposed method consists of three steps: (1) identifying the modal properties of a bridge, such as mode shapes and natural frequencies, based on the ambient vibration under passing vehicles; (2) updating the structural parameters of an initial FE model using the identified modal properties; and (3) predicting the probabilistic fatigue life using the updated FE model. The proposed method is demonstrated by application to a numerical model of a bridge, and the impact of FE model updating on the bridge fatigue life is discussed.

  3. The Prediction of Fatigue Life Based on Four Point Bending Test

    NARCIS (Netherlands)

    Pramesti, F.P.; Molenaar, A.A.A.; Van de Ven, M.F.C.

    2013-01-01

    To be able to devise optimum strategies for maintenance and rehabilitation, it is essential to formulate an accurate prediction of pavement life and its maintenance needs. One of the pavement life prediction methods is based on the pavement's capability to sustain fatigue. If it were possible to hav

  4. Comparison of fatigue life prediction based on local strains and nominal stresses respectively

    International Nuclear Information System (INIS)

    Fatigue life predictions based on local strains and nominal stresses respectively have been performed for notched cylindrical bending test specimens (Ksub(t)=1.4, 2.2, 3.3) made of steel 42 Cr Mo 4, Ck 45 and 49 Mn CS 3 under random loading. The results of calculation are compared with relevant test results. The accuracy of the life prediction based on local strains increases the more informations of the notched specimen (e. g. endurance limit, S-N-curve etc.) will be taken into consideration for the life calculation. In the main the accuracy of life prediction based on nominal stresses is dependent on the slope of the S-N-curve assumed to be valid below the endurance limit. By application of relative Miner's rule life prediction can be improved if relevant test results are available. The comparison of the two prediction methods investigated reveals no favour for one of them. Hence, the decision which method should be applied depends on the special problems to be solved. (orig.)

  5. Low Cycle Fatigue Behavior and Life Prediction of a Cast Cobalt-Based Superalloy

    Science.gov (United States)

    Yang, Ho-Young; Kim, Jae-Hoon; Yoo, Keun-Bong

    Co-base superalloys have been applied in the stationary components of gas turbine owing to their excellent high temperature properties. Low cycle fatigue data on ECY-768 reported in a companion paper were used to evaluate fatigue life prediction models. In this study, low cycle fatigue tests are performed as the variables of total strain range and temperatures. The relations between plastic and total strain energy densities and number of cycles to failure are examined in order to predict the low cycle fatigue life of Cobalt-based super alloy at different temperatures. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.

  6. A residual life prediction model based on the generalized σ -N curved surface

    Directory of Open Access Journals (Sweden)

    Zongwen AN

    2016-06-01

    Full Text Available In order to investigate change rule of the residual life of structure under random repeated load, firstly, starting from the statistic meaning of random repeated load, the joint probability density function of maximum stress and minimum stress is derived based on the characteristics of order statistic (maximum order statistic and minimum order statistic; then, based on the equation of generalized σ -N curved surface, considering the influence of load cycles number on fatigue life, a relationship among minimum stress, maximum stress and residual life, that is the σmin(n- σmax(n-Nr(n curved surface model, is established; finally, the validity of the proposed model is demonstrated by a practical case. The result shows that the proposed model can reflect the influence of maximum stress and minimum stress on residual life of structure under random repeated load, which can provide a theoretical basis for life prediction and reliability assessment of structure.

  7. Predicting Pedestrian Flow: A Methodology and a Proof of Concept Based on Real-Life Data

    OpenAIRE

    Maria Davidich; Gerta Köster

    2013-01-01

    Building a reliable predictive model of pedestrian motion is very challenging: Ideally, such models should be based on observations made in both controlled experiments and in real-world environments. De facto, models are rarely based on real-world observations due to the lack of available data; instead, they are largely based on intuition and, at best, literature values and laboratory experiments. Such an approach is insufficient for reliable simulations of complex real-life scenarios: For in...

  8. Predicting pedestrian flow: a methodology and a proof of concept based on real-life data.

    Science.gov (United States)

    Davidich, Maria; Köster, Gerta

    2013-01-01

    Building a reliable predictive model of pedestrian motion is very challenging: Ideally, such models should be based on observations made in both controlled experiments and in real-world environments. De facto, models are rarely based on real-world observations due to the lack of available data; instead, they are largely based on intuition and, at best, literature values and laboratory experiments. Such an approach is insufficient for reliable simulations of complex real-life scenarios: For instance, our analysis of pedestrian motion under natural conditions at a major German railway station reveals that the values for free-flow velocities and the flow-density relationship differ significantly from widely used literature values. It is thus necessary to calibrate and validate the model against relevant real-life data to make it capable of reproducing and predicting real-life scenarios. In this work we aim at constructing such realistic pedestrian stream simulation. Based on the analysis of real-life data, we present a methodology that identifies key parameters and interdependencies that enable us to properly calibrate the model. The success of the approach is demonstrated for a benchmark model, a cellular automaton. We show that the proposed approach significantly improves the reliability of the simulation and hence the potential prediction accuracy. The simulation is validated by comparing the local density evolution of the measured data to that of the simulated data. We find that for our model the most sensitive parameters are: the source-target distribution of the pedestrian trajectories, the schedule of pedestrian appearances in the scenario and the mean free-flow velocity. Our results emphasize the need for real-life data extraction and analysis to enable predictive simulations. PMID:24386186

  9. Predicting pedestrian flow: a methodology and a proof of concept based on real-life data.

    Directory of Open Access Journals (Sweden)

    Maria Davidich

    Full Text Available Building a reliable predictive model of pedestrian motion is very challenging: Ideally, such models should be based on observations made in both controlled experiments and in real-world environments. De facto, models are rarely based on real-world observations due to the lack of available data; instead, they are largely based on intuition and, at best, literature values and laboratory experiments. Such an approach is insufficient for reliable simulations of complex real-life scenarios: For instance, our analysis of pedestrian motion under natural conditions at a major German railway station reveals that the values for free-flow velocities and the flow-density relationship differ significantly from widely used literature values. It is thus necessary to calibrate and validate the model against relevant real-life data to make it capable of reproducing and predicting real-life scenarios. In this work we aim at constructing such realistic pedestrian stream simulation. Based on the analysis of real-life data, we present a methodology that identifies key parameters and interdependencies that enable us to properly calibrate the model. The success of the approach is demonstrated for a benchmark model, a cellular automaton. We show that the proposed approach significantly improves the reliability of the simulation and hence the potential prediction accuracy. The simulation is validated by comparing the local density evolution of the measured data to that of the simulated data. We find that for our model the most sensitive parameters are: the source-target distribution of the pedestrian trajectories, the schedule of pedestrian appearances in the scenario and the mean free-flow velocity. Our results emphasize the need for real-life data extraction and analysis to enable predictive simulations.

  10. A parametric physics based creep life prediction approach to gas turbine blade conceptual design

    Science.gov (United States)

    Smith, Marcus Edward Brockbank

    The required useful service lives of gas turbine components and parts are naturally one of the major design constraints limiting the gas turbine design space. For example, the required service life of a turbine blade limits the firing temperature in the combustor, which in turn limits the performance of the gas turbine. For a cooled turbine blade, it also determines the necessary cooling flow, which has a strong impact on the turbine efficiency. In most gas turbine design practices, the life prediction is only emphasized during or after the detailed design has been completed. Limited life prediction efforts have been made in the early design stages, but these efforts capture only a few of the necessary key factors, such as centrifugal stress. Furthermore, the early stage prediction methods are usually hard coded in the gas turbine system design tools and hidden from the system designer's view. The common failure mechanisms affecting the service life, such as creep, fatigue and oxidation, are highly sensitive to the material temperatures and/or stresses. Calculation of these temperatures and stresses requires that the geometry, material properties, and operating conditions be known; information not typically available in early stages of design. Even without awareness of the errors, the resulting inaccuracy in the life prediction may mislead the system designers when examining a design space which is bounded indirectly by the inaccurate required life constraints. Furthermore, because intensive creep lifing analysis is possible only towards the end of the design process, any errors or changes will cost the engine manufacturer significant money; money that could be saved if more comprehensive creep lifing predictions were possible in the early stages of design. A rapid, physics-based life prediction method could address this problem by enabling the system designer to investigate the design space more thoroughly and accurately. Although not meant as a final decision

  11. Remaining Useful Life Prediction for Lithium-Ion Batteries Based on Gaussian Processes Mixture

    Science.gov (United States)

    Li, Lingling; Wang, Pengchong; Chao, Kuei-Hsiang; Zhou, Yatong; Xie, Yang

    2016-01-01

    The remaining useful life (RUL) prediction of Lithium-ion batteries is closely related to the capacity degeneration trajectories. Due to the self-charging and the capacity regeneration, the trajectories have the property of multimodality. Traditional prediction models such as the support vector machines (SVM) or the Gaussian Process regression (GPR) cannot accurately characterize this multimodality. This paper proposes a novel RUL prediction method based on the Gaussian Process Mixture (GPM). It can process multimodality by fitting different segments of trajectories with different GPR models separately, such that the tiny differences among these segments can be revealed. The method is demonstrated to be effective for prediction by the excellent predictive result of the experiments on the two commercial and chargeable Type 1850 Lithium-ion batteries, provided by NASA. The performance comparison among the models illustrates that the GPM is more accurate than the SVM and the GPR. In addition, GPM can yield the predictive confidence interval, which makes the prediction more reliable than that of traditional models. PMID:27632176

  12. Remaining Useful Life Prediction for Lithium-Ion Batteries Based on Gaussian Processes Mixture.

    Science.gov (United States)

    Li, Lingling; Wang, Pengchong; Chao, Kuei-Hsiang; Zhou, Yatong; Xie, Yang

    2016-01-01

    The remaining useful life (RUL) prediction of Lithium-ion batteries is closely related to the capacity degeneration trajectories. Due to the self-charging and the capacity regeneration, the trajectories have the property of multimodality. Traditional prediction models such as the support vector machines (SVM) or the Gaussian Process regression (GPR) cannot accurately characterize this multimodality. This paper proposes a novel RUL prediction method based on the Gaussian Process Mixture (GPM). It can process multimodality by fitting different segments of trajectories with different GPR models separately, such that the tiny differences among these segments can be revealed. The method is demonstrated to be effective for prediction by the excellent predictive result of the experiments on the two commercial and chargeable Type 1850 Lithium-ion batteries, provided by NASA. The performance comparison among the models illustrates that the GPM is more accurate than the SVM and the GPR. In addition, GPM can yield the predictive confidence interval, which makes the prediction more reliable than that of traditional models. PMID:27632176

  13. Artificial Fish Swarm Algorithm-Based Particle Filter for Li-Ion Battery Life Prediction

    Directory of Open Access Journals (Sweden)

    Ye Tian

    2014-01-01

    Full Text Available An intelligent online prognostic approach is proposed for predicting the remaining useful life (RUL of lithium-ion (Li-ion batteries based on artificial fish swarm algorithm (AFSA and particle filter (PF, which is an integrated approach combining model-based method with data-driven method. The parameters, used in the empirical model which is based on the capacity fade trends of Li-ion batteries, are identified dependent on the tracking ability of PF. AFSA-PF aims to improve the performance of the basic PF. By driving the prior particles to the domain with high likelihood, AFSA-PF allows global optimization, prevents particle degeneracy, thereby improving particle distribution and increasing prediction accuracy and algorithm convergence. Data provided by NASA are used to verify this approach and compare it with basic PF and regularized PF. AFSA-PF is shown to be more accurate and precise.

  14. Creep life prediction based on stochastic model of microstructurally short crack growth

    Science.gov (United States)

    Kitamura, Takayuki; Ohtani, Ryuichi

    1989-01-01

    A nondimensional model of microstructurally short crack growth in creep is developed based on a detailed observation of the creep fracture process of 304 stainless steel. In order to deal with the scatter of small crack growth rate data caused by microstructural inhomogeneity, a random variable technique is used in the model. A cumulative probability of the crack length at an arbitrary time, G(bar a, bar t), and that of the time when a crack reaches an arbitrary length, F(bar t, bar a), are obtained numerically by means of a Monte Carlo method. G(bar a, bar t), and F(bar t, bar a) are the probabilities for a single crack. However, multiple cracks generally initiate on the surface of a smooth specimen from the early stage of creep life to the final stage. Taking into account the multiple crack initiations, the actual crack length distribution observed on the surface of a specimen is predicted by the combination of probabilities for a single crack. The prediction shows a fairly good agreement with the experimental result for creep of 304 stainless steel at 923 K. The probability of creep life is obtained from an assumption that creep fracture takes place when the longest crack reaches a critical length. The observed and predicted scatter of the life is fairly small for the specimens tested.

  15. Predicting service life margins

    Science.gov (United States)

    Egan, G. F.

    1971-01-01

    Margins are developed for equipment susceptible to malfunction due to excessive time or operation cycles, and for identifying limited life equipment so monitoring and replacing is accomplished before hardware failure. Method applies to hardware where design service is established and where reasonable expected usage prediction is made.

  16. A Study on the Unified Damage Model for Creep-Fatigue Interacted Life Prediction of Nickel-base Superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Won; Kang, Dong Hwan [Hanyang Univ., Seoul (Korea, Republic of); Yeom, Jong Taek; Park, Nho Kwang [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2007-07-01

    A methodology for creep-fatigue interacted life prediction of nickel-base superalloy at high temperature is presented enabling the experimentally measured life to be compared with the model predictions. Continuum damage mechanics has been employed to determine the accumulation of damage during the deformation by means of the unified damage model, which is coupled with the material behavior analysis. Several types of low cycle fatigue test at high temperature have been carried out, and thus the effect of plastic strain range together with the relaxed stress to the life can be investigated. Good agreements between the interacted model's predictions and experimental data of the life were obtained.

  17. Remaining useful life prediction based on the Wiener process for an aviation axial piston pump

    Institute of Scientific and Technical Information of China (English)

    Wang Xingjian; Lin Siru; Wang Shaoping; He Zhaomin; Zhang Chao

    2016-01-01

    An aviation hydraulic axial piston pump’s degradation from comprehensive wear is a typical gradual failure model. Accurate wear prediction is difficult as random and uncertain char-acteristics must be factored into the estimation. The internal wear status of the axial piston pump is characterized by the return oil flow based on fault mechanism analysis of the main frictional pairs in the pump. The performance degradation model is described by the Wiener process to predict the remaining useful life (RUL) of the pump. Maximum likelihood estimation (MLE) is performed by utilizing the expectation maximization (EM) algorithm to estimate the initial parameters of the Wiener process while recursive estimation is conducted utilizing the Kalman filter method to estimate the drift coefficient of the Wiener process. The RUL of the pump is then calculated accord-ing to the performance degradation model based on the Wiener process. Experimental results indi-cate that the return oil flow is a suitable characteristic for reflecting the internal wear status of the axial piston pump, and thus the Wiener process-based method may effectively predicate the RUL of the pump.

  18. Reliability-based service life prediction of existing concrete structures under marine environment

    Institute of Scientific and Technical Information of China (English)

    吴灵杰; 周拥军; 寇新建; 蒋萌

    2015-01-01

    Chloride-induced corrosion of the reinforcement is considered as one of the major mechanisms resulting in the reduction of structural resistance of reinforced concrete structural elements located in marine and other aggressive environments. A study of reinforced concrete structures located at the Fangcheng dock in the Beibu Gulf port, China, was present. The result from field survey indicates that the concrete cover depth and chloride diffusion coefficient fit best normal distribution and lognormal distribution, respectively. The service life of structure is about 55 a, while initiation time is 45 a. Sensitivity analysis indicates that the most influential factor of the structure service life prediction is concrete cover, followed by diffusion coefficient, diffusion decay index, critical chloride concentration, surface chloride concentration, current density and localized pitting corrosion. Finally, the effects of diffusion decay index and critical chloride concentration on structure service life prediction are discussed.

  19. Central Nervous System Based Computing Models for Shelf Life Prediction of Soft Mouth Melting Milk Cakes

    Directory of Open Access Journals (Sweden)

    Gyanendra Kumar Goyal

    2012-04-01

    Full Text Available This paper presents the latency and potential of central nervous system based system intelligent computer engineering system for detecting shelf life of soft mouth melting milk cakes stored at 10o C. Soft mouth melting milk cakes are exquisite sweetmeat cuisine made out of heat and acid thickened solidified sweetened milk. In today’s highly competitive market consumers look for good quality food products. Shelf life is a good and accurate indicator to the food quality and safety. To achieve good quality of food products, detection of shelf life is important. Central nervous system based intelligent computing model was developed which detected 19.82 days shelf life, as against 21 days experimental shelf life.

  20. Multi-scale mechanism based life prediction of polymer matrix composites for high temperature airframe applications

    Science.gov (United States)

    Upadhyaya, Priyank

    A multi-scale mechanism-based life prediction model is developed for high-temperature polymer matrix composites (HTPMC) for high temperature airframe applications. In the first part of this dissertation the effect of Cloisite 20A (C20A) nano-clay compounding on the thermo-oxidative weight loss and the residual stresses due to thermal oxidation for a thermoset polymer bismaleimide (BMI) are investigated. A three-dimensional (3-D) micro-mechanics based finite element analysis (FEA) was conducted to investigate the residual stresses due to thermal oxidation using an in-house FEA code (NOVA-3D). In the second part of this dissertation, a novel numerical-experimental methodology is outlined to determine cohesive stress and damage evolution parameters for pristine as well as isothermally aged (in air) polymer matrix composites. A rate-dependent viscoelastic cohesive layer model was implemented in an in-house FEA code to simulate the delamination initiation and propagation in unidirectional polymer composites before and after aging. Double cantilever beam (DCB) experiments were conducted (at UT-Dallas) on both pristine and isothermally aged IM-7/BMI composite specimens to determine the model parameters. The J-Integral based approach was adapted to extract cohesive stresses near the crack tip. Once the damage parameters had been characterized, the test-bed FEA code employed a micromechanics based viscoelastic cohesive layer model to numerically simulate the DCB experiment. FEA simulation accurately captures the macro-scale behavior (load-displacement history) simultaneously with the micro-scale behavior (crack-growth history).

  1. Lithium-ion battery remaining useful life prediction based on grey support vector machines

    Directory of Open Access Journals (Sweden)

    Xiaogang Li

    2015-12-01

    Full Text Available In this article, an improved grey prediction model is proposed to address low-accuracy prediction issue of grey forecasting model. The first step is using a trigonometric function to transform the original data sequence to smooth the data, which is called smoothness of grey prediction model, and then a grey support vector machine model by integrating the improved grey model with support vector machine is introduced. At the initial stage of the model, trigonometric functions and accumulation generation operation can be used to preprocess the data, which enhances the smoothness of the data and reduces the associated randomness. In addition, support vector machine is implemented to establish a prediction model for the pre-processed data and select the optimal model parameters via genetic algorithms. Finally, the data are restored through the ‘regressive generate’ operation to obtain the forecasting data. To prove that the grey support vector machine model is superior to the other models, the battery life data from the Center for Advanced Life Cycle Engineering are selected, and the presented model is used to predict the remaining useful life of the battery. The predicted result is compared to that of grey model and support vector machines. For a more intuitive comparison of the three models, this article quantifies the root mean square errors for these three different models in the case of different ratio of training samples and prediction samples. The results show that the effect of grey support vector machine model is optimal, and the corresponding root mean square error is only 3.18%.

  2. Central Nervous System Based Computing Models for Shelf Life Prediction of Soft Mouth Melting Milk Cakes

    OpenAIRE

    Gyanendra Kumar Goyal; Sumit Goyal

    2012-01-01

    This paper presents the latency and potential of central nervous system based system intelligent computer engineering system for detecting shelf life of soft mouth melting milk cakes stored at 10o C. Soft mouth melting milk cakes are exquisite sweetmeat cuisine made out of heat and acid thickened solidified sweetened milk. In today’s highly competitive market consumers look for good quality food products. Shelf life is a good and accurate indicator to the food quality and safety. To achieve g...

  3. Physics-based Modeling Tools for Life Prediction and Durability Assessment of Advanced Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The technical objectives of this program are: (1) to develop a set of physics-based modeling tools to predict the initiation of hot corrosion and to address pit and...

  4. Developing a support vector machine based QSPR model for prediction of half-life of some herbicides.

    Science.gov (United States)

    Samghani, Kobra; HosseinFatemi, Mohammad

    2016-07-01

    The half-life (t1/2) of 58 herbicides were modeled by quantitative structure-property relationship (QSPR) based molecular structure descriptors. After calculation and the screening of a large number of molecular descriptors, the most relevant those ones selected by stepwise multiple linear regression were used for developing linear and nonlinear models which developed by using multiple linear regression and support vector machine, respectively. Comparison between statistical parameters of linear and nonlinear models indicates the suitability of SVM over MLR model for predicting the half-life of herbicides. The statistical parameters of R(2) and standard error for training set of SVM model were; 0.96 and 0.087, respectively, and were 0.93 and 0.092 for the test set. The SVM model was evaluated by leave one out cross validation test, which its result indicates the robustness and predictability of the model. The established SVM model was used for predicting the half-life of other herbicides that are located in the applicability domain of model that were determined via leverage approach. The results of this study indicate that the relationship among selected molecular descriptors and herbicide's half-life is non-linear. These results emphases that the process of degradation of herbicides in the environment is very complex and can be affected by various environmental and structural features, therefore simple linear model cannot be able to successfully predict it. PMID:26970881

  5. Thermomechanical fatigue – Damage mechanisms and mechanism-based life prediction methods

    Indian Academy of Sciences (India)

    H-J Christ; A Jung; H J Maier; R Teteruk

    2003-02-01

    An existing extensive database on the isothermal and thermomechanical fatigue behaviour of high-temperature titanium alloy IMI 834 and dispersoidstrengthened aluminum alloy X8019 in SiC particle-reinforced as well as unreinforced conditions was used to evaluate both the adaptability of fracture mechanics approaches to TMF and the resulting predictive capabilities of determining material life by crack propagation consideration. Selection of the correct microstructural concepts was emphasised and these concepts were, then adjusted by using data from independent experiments in order to avoid any sort of fitting. It is shown that the cyclic -integral ($\\Delta J_{\\text{eff}}$ concept) is suitable to predict the cyclic lifetime for conditions where the total crack propagation rate is approximately identical to pure fatigue crack growth velocity. In the case that crack propagation is strongly affected by creep, the creep–fatigue damage parameter $\\Delta_{C\\ F}$ introduced by Riedel can be successfully applied. If environmental effects are very pronounced, the accelerating influence of corrosion on fatigue crack propagation can no longer implicitly be taken into account in the fatigue crack growth law. Instead, a linear combination of the crack growth rate contributions from plain fatigue (determined in vacuum) and from environmental attack is assumed and found to yield a satisfactory prediction, if the relevant corrosion process is taken into account.

  6. Prediction of Fatigue Life of a Continuous Bridge Girder Based on Vehicle Induced Stress History

    Directory of Open Access Journals (Sweden)

    V.G. Rao

    2003-01-01

    Full Text Available The fatigue damage assessment of bridge components by conducting a full scale fatigue testing is often prohibitive. A need, therefore, exists to estimate the fatigue damage in bridge components by a simulation of bridge-vehicle interaction dynamics due to the action of the actual traffic. In the present paper, a systematic method has been outlined to find the fatigue damage in the continuous bridge girder based on stress range frequency histogram and fatigue strength parameters of the bridge materials. Vehicle induced time history of maximum flexural stresses has been obtained by Monte Carlo simulation process and utilized to develop the stress range frequency histogram taking into consideration of the annual traffic volume. The linear damage accumulation theory is then applied to calculate cumulative damage index and fatigue life of the bridge. Effect of the bridge span, pavement condition, increase of vehicle operating speed, weight and suspension characteristics on fatigue life of the bridge have been examined.

  7. A New Predictive Model Based on the ABC Optimized Multivariate Adaptive Regression Splines Approach for Predicting the Remaining Useful Life in Aircraft Engines

    Directory of Open Access Journals (Sweden)

    Paulino José García Nieto

    2016-05-01

    Full Text Available Remaining useful life (RUL estimation is considered as one of the most central points in the prognostics and health management (PHM. The present paper describes a nonlinear hybrid ABC–MARS-based model for the prediction of the remaining useful life of aircraft engines. Indeed, it is well-known that an accurate RUL estimation allows failure prevention in a more controllable way so that the effective maintenance can be carried out in appropriate time to correct impending faults. The proposed hybrid model combines multivariate adaptive regression splines (MARS, which have been successfully adopted for regression problems, with the artificial bee colony (ABC technique. This optimization technique involves parameter setting in the MARS training procedure, which significantly influences the regression accuracy. However, its use in reliability applications has not yet been widely explored. Bearing this in mind, remaining useful life values have been predicted here by using the hybrid ABC–MARS-based model from the remaining measured parameters (input variables for aircraft engines with success. A correlation coefficient equal to 0.92 was obtained when this hybrid ABC–MARS-based model was applied to experimental data. The agreement of this model with experimental data confirmed its good performance. The main advantage of this predictive model is that it does not require information about the previous operation states of the aircraft engine.

  8. V-Notched Bar Creep Life Prediction: GH3536 Ni-Based Superalloy Under Multiaxial Stress State

    Science.gov (United States)

    Zhang, D. X.; Wang, J. P.; Wen, Z. X.; Liu, D. S.; Yue, Z. F.

    2016-05-01

    In this study, creep experiments on smooth and circumferential V-type notched round bars were conducted in GH3536 Ni-based superalloy at 750 °C to identify notch strengthening effect in notched specimens. FE analysis was carried out, coupled with continuum damage mechanics (CDM), to analyze stress distribution and damage evolution under multiaxial stress state. The creep deformation of smooth specimens and the rupture life of both smooth and notched specimens showed good agreement between experimental results and FE analysis predictions; the creep rupture life for the notched specimen was successfully predicted via the "skeletal point" concept. Both creep damage analysis and the observed fracture morphology suggest that creep rupture started first at the root in the V-type notched specimens, and shifted to the region close to the notch root when the notch was relatively shallow compared to U-type notched specimens.

  9. V-Notched Bar Creep Life Prediction: GH3536 Ni-Based Superalloy Under Multiaxial Stress State

    Science.gov (United States)

    Zhang, D. X.; Wang, J. P.; Wen, Z. X.; Liu, D. S.; Yue, Z. F.

    2016-07-01

    In this study, creep experiments on smooth and circumferential V-type notched round bars were conducted in GH3536 Ni-based superalloy at 750 °C to identify notch strengthening effect in notched specimens. FE analysis was carried out, coupled with continuum damage mechanics (CDM), to analyze stress distribution and damage evolution under multiaxial stress state. The creep deformation of smooth specimens and the rupture life of both smooth and notched specimens showed good agreement between experimental results and FE analysis predictions; the creep rupture life for the notched specimen was successfully predicted via the "skeletal point" concept. Both creep damage analysis and the observed fracture morphology suggest that creep rupture started first at the root in the V-type notched specimens, and shifted to the region close to the notch root when the notch was relatively shallow compared to U-type notched specimens.

  10. Prediction of material creep behaviour for strain based life assessment applications

    Energy Technology Data Exchange (ETDEWEB)

    Rantala, J.H.; Hurst, R.C. [EC JRC IAM, Petten (Netherlands); Bregani, F. [ENEL, Milan (Italy)

    1998-12-31

    In this work the idea of using constant load uniaxial creep test results instead of constant stress results for developing a CDM creep model for the P92 material is demonstrated. Due to limited availability of creep test results this work is based on incomplete test data and a general stress rupture line. In spite of these limitations a material creep model was developed for use in a FE analysis. Using P91 material as an example, a method is proposed to account for differences in strain evolution as a function of stress which normally manifests itself as lower strain values at low stresses in a normalised time-strain plot. This allows the CDM model to be used both in FE analysis and in strain-based life assessment engineering calculations. (orig.) 3 refs.

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

    Science.gov (United States)

    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.

  12. A Microstructure-Based Time-Dependent Crack Growth Model for Life and Reliability Prediction of Turbopropulsion Systems

    Science.gov (United States)

    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.

  13. Actual service life prediction of building components

    DEFF Research Database (Denmark)

    Aagaard, Niels-Jørgen; Brandt, Erik; Hansen, Ernst Jan de Place

    2014-01-01

    , the paper presents an analysis of service life of buildings as such with respect to the use of the building partially based on analysis of data from the nationwide Danish register of buildings and housing as well as turnover in the Danish construction industry from refurbishment and demolition activities...... a condensed method for assessment of life cycle costs for buildings. Estimation of life cycle costs has traditionally been based on predicted service life for building components in terms of technical performance. This paper suggests a method for taking into account other contributing factors...... such as economics, aesthetics and use of the building. Each of these factors is regarded as a stochastic variable and can be seen as competing causes of bringing service life to an end. A model is proposed for combining such variables resulting in the actual service life of building components. Furthermore...

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

    Science.gov (United States)

    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.

  15. LIFE PREDICTION APPROACH FOR RANDOM MULTIAXIAL FATIGUE

    Institute of Scientific and Technical Information of China (English)

    Wang Lei; Wang Dejun

    2005-01-01

    According to the concept of critical plane, a life prediction approach for random multiaxial fatigue is presented. First, the critical plane under the multiaxial random loading is determined based on the concept of the weight-averaged maximum shear strain direction. Then the shear and normal strain histories on the determined critical plane are calculated and taken as the subject of multiaxial load simplifying and multiaxial cycle counting. Furthermore, a multiaxial fatigue life prediction model including the parameters resulted from multiaxial cycle counting is presented and applied to calculating the fatigue damage generated from each cycle. Finally, the cumulative damage is added up using Miner's linear rule, and the fatigue prediction life is given. The experiments under multiaxial loading blocks are used for the verification of the proposed method. The prediction has a good correction with the experimental results.

  16. Rolling Bearing Life Prediction, Theory, and Application

    Science.gov (United States)

    Zaretsky, Erwin V.

    2013-01-01

    A tutorial is presented outlining the evolution, theory, and application of rolling-element bearing life prediction from that of A. Palmgren, 1924; W. Weibull, 1939; G. Lundberg and A. Palmgren, 1947 and 1952; E. Ioannides and T. Harris, 1985; and E. Zaretsky, 1987. Comparisons are made between these life models. The Ioannides-Harris model without a fatigue limit is identical to the Lundberg-Palmgren model. The Weibull model is similar to that of Zaretsky if the exponents are chosen to be identical. Both the load-life and Hertz stress-life relations of Weibull, Lundberg and Palmgren, and Ioannides and Harris reflect a strong dependence on the Weibull slope. The Zaretsky model decouples the dependence of the critical shear stress-life relation from the Weibull slope. This results in a nominal variation of the Hertz stress-life exponent. For 9th- and 8th-power Hertz stress-life exponents for ball and roller bearings, respectively, the Lundberg- Palmgren model best predicts life. However, for 12th- and 10th-power relations reflected by modern bearing steels, the Zaretsky model based on the Weibull equation is superior. Under the range of stresses examined, the use of a fatigue limit would suggest that (for most operating conditions under which a rolling-element bearing will operate) the bearing will not fail from classical rolling-element fatigue. Realistically, this is not the case. The use of a fatigue limit will significantly overpredict life over a range of normal operating Hertz stresses. Since the predicted lives of rolling-element bearings are high, the problem can become one of undersizing a bearing for a particular application.

  17. Predicting the Quality of Life Based on Public Health, Social Support and Self Efficacy in Cardiovascular Patients

    OpenAIRE

    M Behnam Moghadam; A Behnam Moghadam; S Yarian; Hosseini SM; S. Mohammad Hosseini

    2014-01-01

    Backgrounds & aim: nowadays measuring the quality of life in the health care system is imperative. The purpose of this study was to predict the quality of life according to public health, social support and self-efficacy in patients with cardiovascular disease. Methods: the present descriptive cross-sectional study was performed on 70 individuals with cardiovascular disease referred to medical centers and Yasuj clinics selected by purposeful sampling. The Research instruments included th...

  18. FATIGUE LIFE PREDICTION BASED ON MACROSCOPIC PLASTIC ZONE ON FRACTURE SURFACE OF AISI-SAE 1018 STEEL

    Directory of Open Access Journals (Sweden)

    G.M. Domínguez Almaraz

    2010-06-01

    Full Text Available This paper deals with rotating bending fatigue tests at high speed (150 Hz carried out on AISI-SAE 1018 steel with a high content of impurities (non metallic inclusions, for which the high experimental stress inside the specimen is close to the elastic limit of the material. Simulations of rotating loading are obtained by Visual NASTRAN software in order to determine the numerical stresse and strain distributions inside a hypothetical homogeneous specimen; later, this information is used for the experimental set up. A general description of experimental test machine and experimental conditions are developed and then, the experimental results are presented and discussed according the observed failure origin related to the non metallic inclusions and the associated high stress zones. Finally, a simple model is proposed to predict the fatigue life for this non homogeneous steel under high speed rotating bending fatigue tests close to the elastic limit, based on the rate between the visual macro-plastic deformation zone at fracture surface and the total fracture surface, together with the crack initiation inclusion (or inclusions located at this zone.

  19. Programming Useful Life Prediction (PULP) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Accurately predicting Remaining Useful Life (RUL) provides significant benefits—it increases safety and reduces financial and labor resource requirements....

  20. FATIGUE LIFE PREDICTION OF CRANKSHAFT MADE OF MATERIAL 48MnV BASED ON FATIGUE TESTS,DYNAMIC SIMULATION AND FEA

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guoqing; PU Gengqiang; WANG Chengtao

    2006-01-01

    S-N curve and fatigue parameters of 48MnV are obtained using small sample tests and staircase or up and down method, which paves the way for predicting fatigue life of crankshaft made of 48MnV. The fatigue life of the crankshaft of a six-cylinder engine is calculated using different damage models such as S-N method, normal strain approach, Smoth-Watson-Topper (SWT)-Bannantine approach, shear strain approach, and Fatemi-Socie method based on dynamic simulation and finite element analysis (FEA) of crankshaft. The results indicate that the traditional calculation is conservative and the residual fatigue life of crankshaft is sufficient to maintain next life cycle if the crankshaft is remanufactured after its end of life.

  1. Service life prediction and cementitious composites

    DEFF Research Database (Denmark)

    Stoklund Larsen, E.

    The present Ph.D.thesis describes and discusses the applicability of a systematic methodology recommended by CIB W80/RILEM-PSL for sevice life prediction. The report describes the most important inherent and environmental factors affecting the service life of structures of cementitious composites....... On the basis of this discription of factors and experience from a test programme described in SBI Report 222, Service life prediction and fibre reinforced cementitious composites, the applicabillity of the CIB/RILEM methodology is discussed....

  2. Fatigue life prediction method for sucker rods based on local concept; Verfahren zur Lebensdauerabschaetzung der Tiefpumpgestaenge nach dem oertlichen Konzept

    Energy Technology Data Exchange (ETDEWEB)

    Ulmanu, V. [Universitatea Petrol-Gaze, Ploiesti (Romania); Ghofrani, R. [Technische Univ. Clausthal, Clausthal-Zellerfeld (DE). Inst. fuer Erdoel- und Erdgastechnik (ITE)

    2001-04-01

    The paper presents a model to calculate the sucker rod fatigue life based on the 'local concept' and on the 'crack propagation concept'. Typical crack initiation site for sucker rods is the upset or body area close to the upset. The fatigue life of Grade C and Grade D - 25,4 mm diameter sucker rods is calculated, considering the rod with surface transverse discontinuities tolerated by API Standards. The crack initiation S-N (Woehler) curve is calculated based on the experimentally determined fatigue characteristics and on the Neuber's rule for describing the material behaviour at the root of the notch. The fatigue crack propagation life is calculated by numerical integration of the Paris law using an estimation for the stress intensity factor for cylindrical bars with an edge crack. The estimated fatigue life is in good agreement with the Woehler diagramm obtained from the failure analysis of rod fractures in the oil field. (orig.)

  3. Chemiluminescent prediction of service life

    Science.gov (United States)

    Hassell, J. A.; Mendenhall, G. D.; Nathan, R. A.

    1976-01-01

    Technique can be used to predict polymer degradation under actual expected-use conditions, without imposing artificial conditions. Smooth or linear correlations are obtained between chemiluminescence and physical properties of purified polymer gums.

  4. End-of-Discharge and End-of-Life Prediction in Lithium-Ion Batteries with Electrochemistry-Based Aging Models

    Science.gov (United States)

    Daigle, Matthew; Kulkarni, Chetan S.

    2016-01-01

    As batteries become increasingly prevalent in complex systems such as aircraft and electric cars, monitoring and predicting battery state of charge and state of health becomes critical. In order to accurately predict the remaining battery power to support system operations for informed operational decision-making, age-dependent changes in dynamics must be accounted for. Using an electrochemistry-based model, we investigate how key parameters of the battery change as aging occurs, and develop models to describe aging through these key parameters. Using these models, we demonstrate how we can (i) accurately predict end-of-discharge for aged batteries, and (ii) predict the end-of-life of a battery as a function of anticipated usage. The approach is validated through an experimental set of randomized discharge profiles.

  5. A knowledge based system (ESR) assisted assessment of the remaining life time of power plant components predicted by standards

    International Nuclear Information System (INIS)

    The lecture reports on the development of a knowledge based expert system by the MPA, Stuttgart, for assessment of the remaining life time of power plant components. The MPA's programme receivers financial and expert knowledge support from seven European power plant operators, who cooperate in the programme in order to bring together the available practical experience, and to process the information to a pool that can be 'trapped' for pin-pointed use. In addition, the system under development incorporates technical codes and standards, regulations and case studies; it offers the possibility of performing calculations and retrieving or storing data. The (expert) system is intended as a database for assessment of pressurized power plant components operated at elevated temperatures, and is to serve design engineers, operating and monitoring engineers. It is implemented on a PC. The requirements to be fulfilled by the system as well as its functions and applications have been defined to a large extent by the power plant operators. The lecture explains the system design, applications and functioning modes, illustrated by some examples showing the pin-pointed retrievability of stored knowledge, and the user friendliness of the system. (orig.)

  6. PRODUCT DATA PREDICTION WITH UNCERTAINTY IN PRODUCT LIFE CYCLE DESIGN

    Institute of Scientific and Technical Information of China (English)

    Yu Suiran; Wang Chengtao; Kimura Fumihiko

    2003-01-01

    Various kinds of data are used in new product design and more accurate data make the design results more reliable. Even though part of product data can be available directly from the existing similar products, there still leaves a great deal of data unavailable. This makes data prediction a valuable work. A method that can predict data of product under development based on the existing similar products is proposed. Fuzzy theory is used to deal with the uncertainties in data prediction process. The proposed method can be used in life cycle design, life cycle assessment (LCA) etc. Case study on current refrigerator is used as a demonstration example.

  7. Fatigue crack initiation life prediction of railroad

    International Nuclear Information System (INIS)

    Study of multiaxial high-cycle fatigue initiation life prediction for railroad is done in this paper. Using ANSYS 11.0 software three dimensional elasto-plastic finite element model of rail/wheel contact is constructed and fine mesh technique in contact region is used to achieve both computational efficiency and accuracy. Stress analysis is performed and fatigue damage in railroad is evaluated numerically using multiaxial fatigue crack initiation model. Using the stress history during one loading cycle and fatigue damage model, the effects of vertical loading, material hardness material fatigue properties and wheel/rail contact situation on fatigue crack initiation life are investigated.

  8. Multiscale Fatigue Life Prediction for Composite Panels

    Science.gov (United States)

    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.

  9. Life Prediction on a T700 Carbon Fiber Reinforced Cylinder with Limited Accelerated Life Testing Data

    Directory of Open Access Journals (Sweden)

    Ma Xiaobing

    2015-01-01

    Full Text Available An accelerated life testing investigation was conducted on a composite cylinder that consists of aluminum alloy and T700 carbon fiber. The ultimate failure stress predictions of cylinders were obtained by the mixing rule and verified by the blasting static pressure method. Based on the stress prediction of cylinder under working conditions, the constant stress accelerated life test of the cylinder was designed. However, the failure data cannot be sufficiently obtained by the accelerated life test due to the time limitation. Therefore, most of the data presented to be high censored in high stress level and zero-failure data in low stress level. When using the traditional method for rupture life prediction, the results showed to be of lower confidence. In this study, the consistency of failure mechanism for carbon fiber and cylinder was analyzed firstly. According to the analysis result, the statistical test information of carbon fiber could be utilized for the accelerated model constitution. Then, rupture life prediction method for cylinder was proposed based on the accelerated life test data and carbon fiber test data. In this way, the life prediction accuracy of cylinder could be improved obviously, and the results showed that the accuracy of this method increased by 35%.

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

    Science.gov (United States)

    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.

  11. Development of a probabilistic model for the prediction of fatigue life in the very high cycle fatigue (VHCF range based on inclusion population

    Directory of Open Access Journals (Sweden)

    Kolyshkin A.

    2014-06-01

    Full Text Available The VHCF behaviour of metallic materials containing microstructural defects such as non-metallic inclusions is determined by the size and distribution of the damage dominating defects. In the present paper, the size and location of about 60.000 inclusions measured on the longitudinal and transversal cross sections of AISI 304 sheet form a database for the probabilistic determination of failure-relevant inclusion distribution in fatigue specimens and their corresponding fatigue lifes. By applying the method of Murakami et al. the biggest measured inclusions were used in order to predict the size of failure-relevant inclusions in the fatigue specimens. The location of the crack initiating inclusions was defined based on the modeled inclusion population and the stress distribution in the fatigue specimen, using the probabilistic Monte Carlo framework. Reasonable agreement was obtained between modeling and experimental results.

  12. Thermomechanical fatigue life prediction of high temperature components

    Energy Technology Data Exchange (ETDEWEB)

    Seifert, Thomas; Hartrott, Philipp von; Riedel, Hermann; Siegele, Dieter [Fraunhofer-Inst. fuer Werkstoffmechanik (IWM), Freiburg (Germany)

    2009-07-01

    The aim of the work described in this paper is to provide a computational method for fatigue life prediction of high temperature components, in which the time and temperature dependent fatigue crack growth is a relevant damage mechanism. The fatigue life prediction is based on a law for microcrack growth and a fracture mechanics estimate of the cyclic crack tip opening displacement. In addition, a powerful model for nonisothermal cyclic plasticity is employed, and an efficient laboratory test procedure is proposed for the determination of the model parameters. The models are efficiently implemented into finite element programs and are used to predict the fatigue life of a cast iron exhaust manifold and a notch in the perimeter of a turbine rotor made of a ferritic/martensitic 10%-chromium steel. (orig.)

  13. Creep fatigue life prediction for engine hot section materials (isotropic)

    Science.gov (United States)

    Moreno, Vito; Nissley, David; Lin, Li-Sen Jim

    1985-01-01

    The first two years of a two-phase program aimed at improving the high temperature crack initiation life prediction technology for gas turbine hot section components are discussed. In Phase 1 (baseline) effort, low cycle fatigue (LCF) models, using a data base generated for a cast nickel base gas turbine hot section alloy (B1900+Hf), were evaluated for their ability to predict the crack initiation life for relevant creep-fatigue loading conditions and to define data required for determination of model constants. The variables included strain range and rate, mean strain, strain hold times and temperature. None of the models predicted all of the life trends within reasonable data requirements. A Cycle Damage Accumulation (CDA) was therefore developed which follows an exhaustion of material ductility approach. Material ductility is estimated based on observed similarities of deformation structure between fatigue, tensile and creep tests. The cycle damage function is based on total strain range, maximum stress and stress amplitude and includes both time independent and time dependent components. The CDA model accurately predicts all of the trends in creep-fatigue life with loading conditions. In addition, all of the CDA model constants are determinable from rapid cycle, fully reversed fatigue tests and monotonic tensile and/or creep data.

  14. Theoretical Foundation for Mechanical Products Service Life Prediction

    Science.gov (United States)

    Konovodov, V. V.; Valentov, A. V.; Lafetova, T. V.; Basalaev, M. N.

    2016-04-01

    The article presents theoretical foundations for prediction of service life of mechanical products, based on the fatigue theory and fatigue limit. Ultimate amplitude and ultimate stress diagrams are presented. Wohler curve, characterizing material durability, is constructed on the results of the tests.

  15. Towards a unified fatigue life prediction method for marine structures

    CERN Document Server

    Cui, Weicheng; Wang, Fang

    2014-01-01

    In order to apply the damage tolerance design philosophy to design marine structures, accurate prediction of fatigue crack growth under service conditions is required. Now, more and more people have realized that only a fatigue life prediction method based on fatigue crack propagation (FCP) theory has the potential to explain various fatigue phenomena observed. In this book, the issues leading towards the development of a unified fatigue life prediction (UFLP) method based on FCP theory are addressed. Based on the philosophy of the UFLP method, the current inconsistency between fatigue design and inspection of marine structures could be resolved. This book presents the state-of-the-art and recent advances, including those by the authors, in fatigue studies. It is designed to lead the future directions and to provide a useful tool in many practical applications. It is intended to address to engineers, naval architects, research staff, professionals and graduates engaged in fatigue prevention design and survey ...

  16. Very High Cycle Fatigue Failure Analysis and Life Prediction of Cr-Ni-W Gear Steel Based on Crack Initiation and Growth Behaviors

    Directory of Open Access Journals (Sweden)

    Hailong Deng

    2015-12-01

    Full Text Available The unexpected failures of structural materials in very high cycle fatigue (VHCF regime have been a critical issue in modern engineering design. In this study, the VHCF property of a Cr-Ni-W gear steel was experimentally investigated under axial loading with the stress ratio of R = −1, and a life prediction model associated with crack initiation and growth behaviors was proposed. Results show that the Cr-Ni-W gear steel exhibits the constantly decreasing S-N property without traditional fatigue limit, and the fatigue strength corresponding to 109 cycles is around 485 MPa. The inclusion-fine granular area (FGA-fisheye induced failure becomes the main failure mechanism in the VHCF regime, and the local stress around the inclusion play a key role. By using the finite element analysis of representative volume element, the local stress tends to increase with the increase of elastic modulus difference between inclusion and matrix. The predicted crack initiation life occupies the majority of total fatigue life, while the predicted crack growth life is only accounts for a tiny fraction. In view of the good agreement between the predicted and experimental results, the proposed VHCF life prediction model involving crack initiation and growth can be acceptable for inclusion-FGA-fisheye induced failure.

  17. C²SLDS: a WSN-based perishable food shelf-life prediction and LSFO strategy decision support system in cold chain logistics

    OpenAIRE

    Qi, Lin; Xu, Mark; Fu, Zetian; Mira, Trebar; Zhang, Xiaoshuan

    2014-01-01

    Temperature monitoring, shelf-life visibility and Least Shelf-life First Out (LSFO) stock strategy are important contents in perishable food cold chain logistics for both cold chain managers and workers in order to reduce quality and economic losses. This paper illustrates a wireless sensor network (WSN) based integrated Cold Chain Shelf Life Decision Support System (C²SLDS) designed for perishable food product cold chain management. The system is implemented based on the WSN and time tempera...

  18. Practical theories for service life prediction of critical aerospace structural components

    Science.gov (United States)

    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.

  19. A survey on life prediction of equipment

    Directory of Open Access Journals (Sweden)

    Hu Changhua

    2015-02-01

    Full Text Available Once in the hands of end users, such durable equipment as spacecraft, aircraft, ships, automobiles, computers, etc. are in a state of debugging, working or storage. In either state, availability, reliability and super-efficiency are the ultimate goals, which have been achieved through constant monitoring as well as regular, preventive, routine and corrective maintenance. Although some advanced instruments can visualize certain invisible malfunctioning phenomena into visible ones, deeply hidden troubles cannot be found unless monitoring and testing data are addressed using tools that process the data statistically, analytically and mathematically. Some state-of-the-art trouble-shooting and life-predicting techniques and approaches are introduced in this paper.

  20. A survey on life prediction of equipment

    Institute of Scientific and Technical Information of China (English)

    Hu Changhua; Zhou Zhijie; Zhang Jianxun; Si Xiaosheng

    2015-01-01

    Once in the hands of end users, such durable equipment as spacecraft, aircraft, ships, automobiles, computers, etc. are in a state of debugging, working or storage. In either state, avail-ability, reliability and super-efficiency are the ultimate goals, which have been achieved through constant monitoring as well as regular, preventive, routine and corrective maintenance. Although some advanced instruments can visualize certain invisible malfunctioning phenomena into visible ones, deeply hidden troubles cannot be found unless monitoring and testing data are addressed using tools that process the data statistically, analytically and mathematically. Some state-of-the-art trouble-shooting and life-predicting techniques and approaches are introduced in this paper.

  1. Building Kinetic Models for Determining Vitamin C Content in Fresh Jujube and Predicting Its Shelf Life Based on Near-Infrared Spectroscopy

    OpenAIRE

    Yaohua Hu; Cong Liu; Qian Hao; Qiang Zhang; Yong He

    2013-01-01

    Fresh jujube (Ziziphus jujube) is rich in vitamin C, which is an important quality index and generally decreases with storage time. The aim of this study was to build kinetic models for determining the vitamin C content, thus predicting the quality characteristics and shelf life of fresh jujube. The quality changes of the jujube stored at room temperature (20 °C) were analyzed using near-infrared spectroscopy. The significant spectra were determined and a calibration model for vitamin C conte...

  2. Prediction Approach to Life on Wing for Civil Aeroengine

    Institute of Scientific and Technical Information of China (English)

    RONG Xiang; ZUO Hong-fu; ZHANG Hai-jun

    2008-01-01

    To reduce engine maintenance cost and support safe operation, a prediction method of engine life on wing was proposed. This method is a kind of regression model which is a function of the condition monitoring and failure data. Key causes of engine removals were analyzed, and the life limit due to performance deterioration was predicted by proportional hazards model. Then the scheduled removal causes were considered as constraints of engine life to predicte the final life on wing. Application of the proposed prediction method to the case of CF6-80C2A5 engine fleet in an airline proved its effectiveness.

  3. 维纳过程寿命预测的一种自助法%A bootstrap method of life prediction based on Wiener process

    Institute of Scientific and Technical Information of China (English)

    周经伦; 厉海涛; 刘学敏; 金光; 周忠宝

    2011-01-01

    With respect to the problem that traditional Wiener process can't characterize the difference between the population and the individual, this paper proposes a bootstrap method to solve the problem. First of all, we use normal distribution to describe the drift parameter and volatility parameter of Wiener process. Then, we generate the bootstrap sample through bootstrap estimation of the parameter. Finally, based on the bootstrap sample, the population degradation parameters are obtained and the lifetime of product is predicted. A long life product in spaceflight is presented as an example to validate the method.%针对传统的维纳过程寿命预测方法未能有效考虑产品总体和个体之间的差异问题,提出了解决该问题的一种自助法.首先,利用正态分布来描述产品总体维纳过程退化模型的漂移参数和扩散参数;然后,对个体的性能退化参数进行自助估计并得到多组自助样本;最后,根据个体退化参数的自助样本对总体退化参数的分布进行估计,获取其多组自助样本并对总体的寿命进行预测.通过对某航天长寿命产品的实例分析验证了该方法的有效性.

  4. Life history traits to predict biogeographic species distributions in bivalves

    Science.gov (United States)

    Montalto, V.; Rinaldi, A.; Sarà, G.

    2015-10-01

    Organismal fecundity ( F) and its relationship with body size (BS) are key factors in predicting species distribution under current and future scenarios of global change. A functional trait-based dynamic energy budget (FT-DEB) is proposed as a mechanistic approach to predict the variation of F and BS as function of environmental correlates using two marine bivalves as model species ( Mytilus galloprovincialis and Brachidontes pharaonis). Validation proof of model skill (i.e., degree of correspondence between model predictions and field observations) and stationarity (i.e., ability of a model generated from data collected at one place/time to predict processes at another place/time) was provided to test model performance in predicting the bivalve distribution throughout the 22 sites in the Central Mediterranean Sea under local conditions of food density and body temperature. Model skill and stationarity were tested through the estimate of commission (i.e., proportion of species' absences predicted present) and omission (i.e., proportion of presences predicted absent) errors of predictions by comparing mechanistic predicted vs. observed F and BS values throughout the study area extrapolated by lab experiments and literature search. The resulting relationship was reliable for both species, and body size and fecundity were highly correlated in M. galloprovincialis compared to B. pharaonis; FT-DEB showed correct predictions of presence in more than 75 % of sites, and the regression between BS predicted vs. observed was highly significant in both species. Whilst recognising the importance of biotic interactions in shaping the distribution of species, our FT-DEB approach provided reliable quantitative estimates of where our species had sufficient F to support local populations or suggesting reproductive failure. Mechanistically, estimating F and BS as key traits of species life history can also be addressed within a broader, scale-dependent context that surpasses the

  5. Shelf-Life Prediction of Chilled Foods

    Science.gov (United States)

    Gudmundsson, Gudmundur; Kristbergsson, Kristberg

    All foods have a finite shelf life. Even foods, which mature with time, will in the end deteriorate, although their life span can exceed 100 years. Definitions of shelf life of food products differ. Some stress the suitability of the product for consump¬tion, others for how long the product can be sold. The Institute of Food Science and Technology emphasizes safety in its definition of shelf life: "The period of time under defined conditions of storage, after manufacture or packing, for which a food product will remain safe and be fit for use" ( http://www.ifst.org ). This definition does not describe what makes a food product "safe" or "fit" for use, but one can say all factors which restrict the shelf life of a food product either affect safety or quality or both.

  6. Entropy and the Predictability of Online Life

    CERN Document Server

    Sinatra, Roberta

    2014-01-01

    Using mobile phone records and information theory measures, our daily lives have been recently shown to follow strict statistical regularities, and our movement patterns are to a large extent predictable. Here, we apply entropy and predictability measures to two data sets of the behavioral actions and the mobility of a large number of players in the virtual universe of a massive multiplayer online game. We find that movements in virtual human lives follow the same high levels of predictability as offline mobility, where future movements can to some extent be predicted well if the temporal correlations of visited places are accounted for. Time series of behavioral actions show similar high levels of predictability, even when temporal correlations are neglected. Entropy conditional on specific behavioral actions reveals that in terms of predictability negative behavior has a wider variety than positive actions. The actions which contain information to best predict an individual's subsequent action are negative,...

  7. Life Prediction of Tanker Based on MATLAB and ANSYS%基于MATLAB和ANSYS联合仿真的罐车寿命预测

    Institute of Scientific and Technical Information of China (English)

    辛天佐; 李守成

    2012-01-01

    采用名义应力法来预测罐车的疲劳寿命。通过MATLAB模拟得到符合实际运行工况的A级路面的随机激励,将罐车的钢板弹簧和轮胎的刚度进行等效处理,并利用模态综合法,得出最大应力点的应力-时间曲线。根据材料的p-S-N曲线和米勒线性疲劳累积损伤理论,得出失效应力循环次数,并预测出整个罐车的疲劳寿命。%The nominal stress method is used to predict the fatigue life of a tanker in this paper.We obtained A-class road random excitation in realistic operating condition by establishing MATLAB procedure,finished equivalent processing for the stiffness of the tanker’s steel springs and tire,and obtained stress-time curve of the maximum stress point by modal synthesis method.According to the p-S-N curve of the material,considering Miller linear fatigue cumulative damage theory,the number of stress cycle was counted,and the fatigue life of the entire tanker was predicted.

  8. Entropy and the Predictability of Online Life

    Directory of Open Access Journals (Sweden)

    Roberta Sinatra

    2014-01-01

    Full Text Available Using mobile phone records and information theory measures, our daily lives have been recently shown to follow strict statistical regularities, and our movement patterns are, to a large extent, predictable. Here, we apply entropy and predictability measures to two datasets of the behavioral actions and the mobility of a large number of players in the virtual universe of a massive multiplayer online game. We find that movements in virtual human lives follow the same high levels of predictability as offline mobility, where future movements can, to some extent, be predicted well if the temporal correlations of visited places are accounted for. Time series of behavioral actions show similar high levels of predictability, even when temporal correlations are neglected. Entropy conditional on specific behavioral actions reveals that in terms of predictability, negative behavior has a wider variety than positive actions. The actions that contain the information to best predict an individual’s subsequent action are negative, such as attacks or enemy markings, while the positive actions of friendship marking, trade and communication contain the least amount of predictive information. These observations show that predicting behavioral actions requires less information than predicting the mobility patterns of humans for which the additional knowledge of past visited locations is crucial and that the type and sign of a social relation has an essential impact on the ability to determine future behavior.

  9. Service life prediction and fibre reinforced cementitious composites

    DEFF Research Database (Denmark)

    Stoklund Larsen, E.

    The present Ph.D.thesis addresses the service life concept on the fibre reinforced cementitious composites. The advantages and problems of adding fibre to a cementitious matrix and the influence on service life are described. In SBI Report 221, Service life prediction and cementitious somposites...

  10. Predicting Battery Life for Electric UAVs

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper presents a novel battery health management technology for the new generation of electric unmanned aerial vehicles powered by long-life, high-density,...

  11. Patterns, entropy, and predictability of human mobility and life.

    Directory of Open Access Journals (Sweden)

    Shao-Meng Qin

    Full Text Available Cellular phones are now offering an ubiquitous means for scientists to observe life: how people act, move and respond to external influences. They can be utilized as measurement devices of individual persons and for groups of people of the social context and the related interactions. The picture of human life that emerges shows complexity, which is manifested in such data in properties of the spatiotemporal tracks of individuals. We extract from smartphone-based data for a set of persons important locations such as "home", "work" and so forth over fixed length time-slots covering the days in the data-set (see also [1], [2]. This set of typical places is heavy-tailed, a power-law distribution with an exponent close to -1.7. To analyze the regularities and stochastic features present, the days are classified for each person into regular, personal patterns. To this are superimposed fluctuations for each day. This randomness is measured by "life" entropy, computed both before and after finding the clustering so as to subtract the contribution of a number of patterns. The main issue that we then address is how predictable individuals are in their mobility. The patterns and entropy are reflected in the predictability of the mobility of the life both individually and on average. We explore the simple approaches to guess the location from the typical behavior, and of exploiting the transition probabilities with time from location or activity A to B. The patterns allow an enhanced predictability, at least up to a few hours into the future from the current location. Such fixed habits are most clearly visible in the working-day length.

  12. Predicting remaining life in upper sugar-mill shafts

    Directory of Open Access Journals (Sweden)

    Sara Rodríguez Pulecio

    2010-04-01

    Full Text Available A fracture mechanics-based method is presented for determining critical crack size and residual life of upper sugar-mill shafts having semi-elliptical and circumferential cracks. Due to the multiaxial stress field, an equivalent strain energy release rate stress intensity solution is used in Paris’ law to predict crack growth. Ultrasonic inspection intervals for the shaft were established. The crack zone evaluated was located in the shoulder of the bearing nearest to the square box coupling where about 25% of service failures in these types of shaft are observed.

  13. 基于加速寿命试验的液浮陀螺仪寿命预测%Research on Working Life Prediction of Liquid Floated Gyroscope Based on Accelerated Life Tests

    Institute of Scientific and Technical Information of China (English)

    彭志凌; 杨晋伟; 邵轶群; 范晓东

    2014-01-01

    Taking the liquid floated gyroscope as the research object ,on the basis of analyzing the gyroscope structure features and working principle ,its reliability model was established .Acceleration model and acceler-ated life test plan were determined .Used the temperature and humidity incubator to test and processed the test data ,predicted the working life of liquid floating gyro was 5031 .9 hours by Weibull distribution and maximum likelihood estimation .By using the method ,the cost effectiveness of the liquid floated gyroscope life prediction is improved and provide an important way to predict the life of such products .%以液浮陀螺仪为研究对象,在分析陀螺仪结构功能和工作原理的基础上,建立可靠性模型.确定了工作条件下的加速模型和加速寿命试验方案,利用恒湿恒温箱进行试验,对获取的试验数据进行处理.利用威布尔分布和极大似然估计预测了某液浮陀螺仪的工作寿命为5031.9 h.所采用的的方法提高了液浮陀螺仪寿命预测的费效比,为预测此类产品寿命提供了一种重要方法.

  14. Fatigue life prediction modeling for turbine hot section materials

    Science.gov (United States)

    Halford, G. R.; Meyer, T. G.; Nelson, R. S.; Nissley, D. M.; Swanson, G. A.

    1989-01-01

    A major objective of the fatigue and fracture efforts under the NASA Hot Section Technology (HOST) program was to significantly improve the analytic life prediction tools used by the aeronautical gas turbine engine industry. This was achieved in the areas of high-temperature thermal and mechanical fatigue of bare and coated high-temperature superalloys. The cyclic crack initiation and propagation resistance of nominally isotropic polycrystalline and highly anisotropic single crystal alloys were addressed. Life prediction modeling efforts were devoted to creep-fatigue interaction, oxidation, coatings interactions, multiaxiality of stress-strain states, mean stress effects, cumulative damage, and thermomechanical fatigue. The fatigue crack initiation life models developed to date include the Cyclic Damage Accumulation (CDA) and the Total Strain Version of Strainrange Partitioning (TS-SRP) for nominally isotropic materials, and the Tensile Hysteretic Energy Model for anisotropic superalloys. A fatigue model is being developed based upon the concepts of Path-Independent Integrals (PII) for describing cyclic crack growth under complex nonlinear response at the crack tip due to thermomechanical loading conditions. A micromechanistic oxidation crack extension model was derived. The models are described and discussed.

  15. Time-dependent fatigue--phenomenology and life prediction

    International Nuclear Information System (INIS)

    The time-dependent fatigue behavior of materials used or considered for use in present and advanced systems for power generation is outlined. A picture is first presented to show how basic mechanisms and phenomenological information relate to the performance of the component under consideration through the so-called local strain approach. By this means life prediction criteria and design rules can be formulated utilizing laboratory test information which is directly translated to predicting the performance of a component. The body of phenomenological information relative to time-dependent fatigue is reviewed. Included are effects of strain range, strain rate and frequency, environment and wave shape, all of which are shown to be important in developing both an understanding and design base for time dependent fatigue. Using this information, some of the current methods being considered for the life prediction of components are reviewed. These include the current ASME code case, frequency-modified fatigue equations, strain range partitioning, the damage function method, frequency separation and damage rate equations. From this review, it is hoped that a better perspective on future directions for basic material science at high temperature can be achieved

  16. Entropy and the Predictability of Online Life

    OpenAIRE

    Roberta Sinatra; Michael Szell

    2013-01-01

    Using mobile phone records and information theory measures, our daily lives have been recently shown to follow strict statistical regularities, and our movement patterns are, to a large extent, predictable. Here, we apply entropy and predictability measures to two datasets of the behavioral actions and the mobility of a large number of players in the virtual universe of a massive multiplayer online game. We find that movements in virtual human lives follow the same high levels of predictabili...

  17. Genetic Risk Score Predicts Late-Life Cognitive Impairment

    Directory of Open Access Journals (Sweden)

    Mariegold E. Wollam

    2015-01-01

    Full Text Available Introduction. A family history of Alzheimer’s disease is a significant risk factor for its onset, but the genetic risk associated with possessing multiple risk alleles is still poorly understood. Methods. In a sample of 95 older adults (Mean age = 75.1, 64.2% female, we constructed a genetic risk score based on the accumulation of risk alleles in BDNF, COMT, and APOE. A neuropsychological evaluation and consensus determined cognitive status (44 nonimpaired, 51 impaired. Logistic regression was performed to determine whether the genetic risk score predicted cognitive impairment above and beyond that associated with each gene. Results. An increased genetic risk score was associated with a nearly 4-fold increased risk of cognitive impairment (OR = 3.824, P = .013 when including the individual gene polymorphisms as covariates in the model. Discussion. A risk score combining multiple genetic influences may be more useful in predicting late-life cognitive impairment than individual polymorphisms.

  18. Enhanced Prediction of Gear Tooth Surface Fatigue Life Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Sentient will develop an enhanced prediction of gear tooth surface fatigue life with rigorous analysis of the tribological phenomena that contribute to pitting...

  19. Probabilistic Fatigue Life Prediction of Turbine Disc Considering Model Parameter Uncertainty

    Science.gov (United States)

    He, Liping; Yu, Le; Zhu, Shun-Peng; Ding, Liangliang; Huang, Hong-Zhong

    2016-06-01

    Aiming to improve the predictive ability of Walker model for fatigue life prediction and taking the turbine disc alloy GH4133 as the application example, this paper investigates a new approach for probabilistic fatigue life prediction when considering parameter uncertainty inherent in the life prediction model. Firstly, experimental data are used to update the model parameters using Bayes' theorem, so as to obtain the posterior probability distribution functions of two parameters of the Walker model, as well to achieve the probabilistic life prediction model for turbine disc. During the updating process, Markov Chain Monte Carlo (MCMC) technique is used to generate samples of the given distribution and estimating the parameters distinctly. After that, the turbine disc life is predicted using the probabilistic Walker model based on Monte Carlo simulation technique. The experimental results indicate that: (1) after using the small sample test data obtained from turbine disc, parameter uncertainty of the Walker model can be quantified and the corresponding probabilistic model for fatigue life prediction can be established using Bayes' theorem; (2) there exists obvious dispersion of life data for turbine disc when predicting fatigue life in practical engineering application.

  20. Predictive and Treatment Validity of Life Satisfaction and the Quality of Life Inventory

    Science.gov (United States)

    Frisch, Michael B.; Clark, Michelle P.; Rouse, Steven V.; Rudd, M. David; Paweleck, Jennifer K.; Greenstone, Andrew; Kopplin, David A.

    2005-01-01

    The clinical and positive psychology usefulness of quality of life, well-being, and life satisfaction assessments depends on their ability to predict important outcomes and to detect intervention-related change. These issues were explored in the context of a program of instrument validation for the Quality of Life Inventory (QOLI) involving 3,927…

  1. Computational Methods for Failure Analysis and Life Prediction

    Science.gov (United States)

    Noor, Ahmed K. (Compiler); Harris, Charles E. (Compiler); Housner, Jerrold M. (Compiler); Hopkins, Dale A. (Compiler)

    1993-01-01

    This conference publication contains the presentations and discussions from the joint UVA/NASA Workshop on Computational Methods for Failure Analysis and Life Prediction held at NASA Langley Research Center 14-15 Oct. 1992. The presentations focused on damage failure and life predictions of polymer-matrix composite structures. They covered some of the research activities at NASA Langley, NASA Lewis, Southwest Research Institute, industry, and universities. Both airframes and propulsion systems were considered.

  2. Service life prediction of exterior plastics vision for the future

    CERN Document Server

    Martin, Jon; Chapin, J

    2015-01-01

    This book defines the current state-of-the-art for predicting the lifetime of plastics exposed to weather and outlines future research needed to advance this important field of study. Coverage includes progress in developing new science and test methods to determine how materials respond to weather exposure. This book is ideal for researchers and professionals working in the field of service life prediction. This book also: Examines numerous consensus standards that affect commercial products allowing readers to see the future of standards related to service life prediction Provides the scientific foundation for the latest commercially viable instruments Presents groundbreaking research, including the blueprint of a new test method that will significantly shorten the service life prediction process time Covers two of the latest verified predictive models, which demonstrate realized-potential to transform the field

  3. Thermal barrier coating life prediction model development

    Science.gov (United States)

    Strangman, T. E.; Neumann, J. F.; Liu, A.

    1986-01-01

    Thermal barrier coatings (TBCs) for turbine airfoils in high-performance engines represent an advanced materials technology with both performance and durability benefits. The foremost TBC benefit is the reduction of heat transferred into air-cooled components, which yields performance and durability benefits. This program focuses on predicting the lives of two types of strain-tolerant and oxidation-resistant TBC systems that are produced by commercial coating suppliers to the gas turbine industry. The plasma-sprayed TBC system, composed of a low-pressure plasma-spray (LPPS) or an argon shrouded plasma-spray (ASPS) applied oxidation resistant NiCrAlY (or CoNiCrAlY) bond coating and an air-plasma-sprayed yttria (8 percent) partially stabilized zirconia insulative layer, is applied by Chromalloy, Klock, and Union Carbide. The second type of TBC is applied by the electron beam-physical vapor deposition (EB-PVD) process by Temescal.

  4. Theory of Economic Life Prediction and Reliability Assessment of Aircraft Structures

    Institute of Scientific and Technical Information of China (English)

    YAN Chuliang; LIU Kege

    2011-01-01

    The theory of economic life prediction and reliability assessment of aircraft structures has a significant effect on safety of aircraft structures.It is based on the two-stage theory of fatigue process and can guarantee the safety and reliability of structures.According to the fatigue damage process, the fatigue scatter factors of crack initiation stage and crack propagation stage are given respectively.At the same time, mathematical models of fatigue life prediction are presented by utilizing the fatigue scatter factors and full scale test results of aircraft structures.Furthermore, the economic life model is put forward.The model is of significant scientific value for products to provide longer economic life, higher reliability and lower cost.The theory of economic life prediction and reliability assessment of aircraft structures has been successfully applied to determining and extending the structural life for thousands of airplanes.

  5. Prediction and evaluation of route dependent dosimetry of BPA in rats at different life stages using a physiologically based pharmacokinetic model

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaoxia, E-mail: Xiaoxia.Yang@fda.hhs.gov; Doerge, Daniel R.; Fisher, Jeffrey W.

    2013-07-01

    Bisphenol A (BPA) has received considerable attention throughout the last decade due to its widespread use in consumer products. For the first time a physiologically based pharmacokinetic (PBPK) model was developed in neonatal and adult rats to quantitatively evaluate age-dependent pharmacokinetics of BPA and its phase II metabolites. The PBPK model was calibrated in adult rats using studies on BPA metabolism and excretion in the liver and gastrointestinal tract, and pharmacokinetic data with BPA in adult rats. For immature rats the hepatic and gastrointestinal metabolism of BPA was inferred from studies on the maturation of phase II enzymes coupled with serum time course data in pups. The calibrated model predicted the measured serum concentrations of BPA and BPA conjugates after administration of 100 μg/kg of d6-BPA in adult rats (oral gavage and intravenous administration) and postnatal days 3, 10, and 21 pups (oral gavage). The observed age-dependent BPA serum concentrations were partially attributed to the immature metabolic capacity of pups. A comparison of the dosimetry of BPA across immature rats and monkeys suggests that dose adjustments would be necessary to extrapolate toxicity studies from neonatal rats to infant humans. - Highlights: • A PBPK model predicts the kinetics of bisphenol A (BPA) in young and adult rats. • BPA metabolism within enterocytes is required for fitting of oral BPA kinetic data. • BPA dosimetry in young rats is different than adult rats and young monkeys.

  6. Application of time-temperature superposition method in thermal aging life prediction of shipboard cables

    Institute of Scientific and Technical Information of China (English)

    DENG Wen-dong; CHEN Yi-yuan

    2014-01-01

    The life of shipboard cables will decrease due to the complex aging processes. In terms of the safety perspective, remaining life prediction of the cable is essential to maintain a reliable operation. In this paper, firstly, based on Arrhenius equation, residual life of new styrene-butadiene cable is calculated;result indicates that the degradation rate which changes with time is proportional to thermal temperature. Then second order dynamic model is adopted into the residual life prediction, combined with the time-temperature superposition method (TTSP), and a new residual life model is proposed. According to the accelerated thermal aging experiment data and Arrhenius equation, TTSP method demonstrates to be an efficient way for life prediction, and life at normal temperature can be estimated by this model. In order to monitor the state of styrene-butadiene cable more accurately, an improved residual life model based on equivalent environment temperature of cable is proposed, and life of cable under real operation is analyzed. Result indicates that this model is credible and reliable, and it provides an important theoretical base for residual life of cables.

  7. Fatigue life prediction and strength degradation of wind turbine rotor blade composites

    NARCIS (Netherlands)

    Nijssen, R.P.L.

    2006-01-01

    Wind turbine rotor blades are subjected to a large number of highly variable loads, but life predictions are typically based on constant amplitude fatigue behaviour. Therefore, it is important to determine how service life under variable amplitude fatigue can be estimated from constant amplitude fat

  8. Neural Network Modeling to Predict Shelf Life of Greenhouse Lettuce

    Directory of Open Access Journals (Sweden)

    Wei-Chin Lin

    2009-04-01

    Full Text Available Greenhouse-grown butter lettuce (Lactuca sativa L. can potentially be stored for 21 days at constant 0°C. When storage temperature was increased to 5°C or 10°C, shelf life was shortened to 14 or 10 days, respectively, in our previous observations. Also, commercial shelf life of 7 to 10 days is common, due to postharvest temperature fluctuations. The objective of this study was to establish neural network (NN models to predict the remaining shelf life (RSL under fluctuating postharvest temperatures. A box of 12 - 24 lettuce heads constituted a sample unit. The end of the shelf life of each head was determined when it showed initial signs of decay or yellowing. Air temperatures inside a shipping box were recorded. Daily average temperatures in storage and averaged shelf life of each box were used as inputs, and the RSL was modeled as an output. An R2 of 0.57 could be observed when a simple NN structure was employed. Since the "future" (or remaining storage temperatures were unavailable at the time of making a prediction, a second NN model was introduced to accommodate a range of future temperatures and associated shelf lives. Using such 2-stage NN models, an R2 of 0.61 could be achieved for predicting RSL. This study indicated that NN modeling has potential for cold chain quality control and shelf life prediction.

  9. A method for uncertainty quantification in the life prediction of gas turbine components

    Energy Technology Data Exchange (ETDEWEB)

    Lodeby, K.; Isaksson, O.; Jaervstraat, N. [Volvo Aero Corporation, Trolhaettan (Sweden)

    1998-12-31

    A failure in an aircraft jet engine can have severe consequences which cannot be accepted and high requirements are therefore raised on engine reliability. Consequently, assessment of the reliability of life predictions used in design and maintenance are important. To assess the validity of the predicted life a method to quantify the contribution to the total uncertainty in the life prediction from different uncertainty sources is developed. The method is a structured approach for uncertainty quantification that uses a generic description of the life prediction process. It is based on an approximate error propagation theory combined with a unified treatment of random and systematic errors. The result is an approximate statistical distribution for the predicted life. The method is applied on life predictions for three different jet engine components. The total uncertainty became of reasonable order of magnitude and a good qualitative picture of the distribution of the uncertainty contribution from the different sources was obtained. The relative importance of the uncertainty sources differs between the three components. It is also highly dependent on the methods and assumptions used in the life prediction. Advantages and disadvantages of this method is discussed. (orig.) 11 refs.

  10. Purpose in life predicts better emotional recovery from negative stimuli.

    Directory of Open Access Journals (Sweden)

    Stacey M Schaefer

    Full Text Available Purpose in life predicts both health and longevity suggesting that the ability to find meaning from life's experiences, especially when confronting life's challenges, may be a mechanism underlying resilience. Having purpose in life may motivate reframing stressful situations to deal with them more productively, thereby facilitating recovery from stress and trauma. In turn, enhanced ability to recover from negative events may allow a person to achieve or maintain a feeling of greater purpose in life over time. In a large sample of adults (aged 36-84 years from the MIDUS study (Midlife in the U.S., http://www.midus.wisc.edu/, we tested whether purpose in life was associated with better emotional recovery following exposure to negative picture stimuli indexed by the magnitude of the eyeblink startle reflex (EBR, a measure sensitive to emotional state. We differentiated between initial emotional reactivity (during stimulus presentation and emotional recovery (occurring after stimulus offset. Greater purpose in life, assessed over two years prior, predicted better recovery from negative stimuli indexed by a smaller eyeblink after negative pictures offset, even after controlling for initial reactivity to the stimuli during the picture presentation, gender, age, trait affect, and other well-being dimensions. These data suggest a proximal mechanism by which purpose in life may afford protection from negative events and confer resilience is through enhanced automatic emotion regulation after negative emotional provocation.

  11. Assessment of fatigue life of remanufactured impeller based on FEA

    Science.gov (United States)

    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.

  12. Simulation work of fatigue life prediction of rubber automotive components

    Energy Technology Data Exchange (ETDEWEB)

    Samad, M S A [Automotive Engineering Unit, Institute of Advanced Technology, University Putra Malaysia, 43400, UPM Serdang, Selangor (Malaysia); Ali, Aidy, E-mail: aidy@eng.upm.edu.my [Department of Mechanical and Manufacturing Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM, Serdang Selangor (Malaysia)

    2010-05-15

    The usage of rubbers has always been so important, especially in automotive industries. Rubbers have a hyper elastic behaviour which is the ability to withstand very large strain without failure. The normal applications for rubbers are used for shock absorption, sound isolation and mounting. In this study, the predictions of fatigue life of an engine mount of rubber automotive components were presented. The finite element analysis was performed to predict the critical part and the strain output were incorporated into fatigue model for prediction. The predicted result shows agreement in term of failure location of rubber mount.

  13. Life Prediction of Ball Grid Array Soldered Joints under Thermal Cycling Loading by Fracture Mechanics Method

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fatigue crack propagation life of ball grid array (BGA) soldered joints during thermal cycling loading was investigated by fracture mechanics approach using finite element analysis. The relationships between the strain energy release rate (G) and crack size (α), thermal cycle numbers (N) can be derived. Based on the relationships, fatigue life of the soldered joints was determined. The results showed that crack propagation life was higher than crack initiation life. Therefore, it appears that it is more appropriate to predict the fatigue life of soldered joints using the fracture mechanics method.

  14. FORMULASI TEPUNG PENYALUT BERBASIS TEPUNG JAGUNG DAN PENENTUAN UMUR SIMPANNYA DENGAN PENDEKATAN KADAR AIR KRITIS [Formulation of Corn Flour-Based Batter and Prediction of Its Shelf Life using Critical Moisture Approach

    Directory of Open Access Journals (Sweden)

    Sugiyono1*

    2010-12-01

    Full Text Available The objectives of this study were to obtain the best formula for corn flour-based batter and to predict its shelf life using critical moisture approach. According to a hedonic test, the best batter formula was composed of 60% corn flour, 12.5% rice flour, 12.5% tapioca starch, and 15% glutinous rice flour. Addition of glutinous rice flour in the formula changed the proportion of amylose and amylopectin in the batter. As a result, the retrogradation of the batter decreased and the texture of its fried product was preferred. A critical moisture approach was used to predict the shelf life of the batter. The critical moisture content of the batter was 0.16 g H2O/g solid.The isotherm sorption phenomenon of the batter was best described using Hasley model. The shelf life of the product was 7 months when packaged in polypropylene (0,07 g/m2day.mmHg at 85% RH.

  15. Reengineering Aircraft Structural Life Prediction Using a Digital Twin

    Directory of Open Access Journals (Sweden)

    Eric J. Tuegel

    2011-01-01

    Full Text Available Reengineering of the aircraft structural life prediction process to fully exploit advances in very high performance digital computing is proposed. The proposed process utilizes an ultrahigh fidelity model of individual aircraft by tail number, a Digital Twin, to integrate computation of structural deflections and temperatures in response to flight conditions, with resulting local damage and material state evolution. A conceptual model of how the Digital Twin can be used for predicting the life of aircraft structure and assuring its structural integrity is presented. The technical challenges to developing and deploying a Digital Twin are discussed in detail.

  16. FATIGUE LIFE PREDICTION THEORY OF COMPOSITE LAMINATES AND EXPERIMENTAL VERIFICATION

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    According to traditional phenomenological fatigue methodology and modern continuum damage mechanics theory, dual fatigue cumulative damage rules to predict fatigue damage formation and propagation lives of the notched composite laminates are presented.A 3-dimensional damage constitutive equation of anisotropic composites is also established.Damage strain energy release rate is interpreted as a driving force of the fatigue delamination damage propagation.A new damage evolution equation and a damage propagation (a-(m-N( surface (stress amplitude-mean stress-life surface) are derived.Hence, using the method above, the fatigue life of composite components can be predicted.Finally, theoretically predicted results are compared with experimental data.It is found that the deviation of theoretic prediction from experimental results is about 22%.

  17. Neural Network Modeling to Predict Shelf Life of Greenhouse Lettuce

    OpenAIRE

    Wei-Chin Lin; Block, Glen S.

    2009-01-01

    Greenhouse-grown butter lettuce (Lactuca sativa L.) can potentially be stored for 21 days at constant 0°C. When storage temperature was increased to 5°C or 10°C, shelf life was shortened to 14 or 10 days, respectively, in our previous observations. Also, commercial shelf life of 7 to 10 days is common, due to postharvest temperature fluctuations. The objective of this study was to establish neural network (NN) models to predict the remaining shelf life (RSL) under fluctuating postharvest temp...

  18. MACHINE LEARNING MODELS FOR PREDICTING SHELF LIFE OF PROCESSED CHEESE

    OpenAIRE

    Sumit, Goyal; Gyanendra, Goyal

    2013-01-01

    Feedforward multilayer machine learning artificial neural network (ANN) models were established for predicting shelf life of processed cheese stored at 7-8o C. Soluble nitrogen, pH, standard plate count, yeast & mould count, and spore count were input variables, and sensory score was the output variable. Mean Square Error, Root Mean Square Error, Coefficient of Determination and Nash–Sutcliffe Coefficient were used for comparing the prediction ability of the developed models. Feedforward ...

  19. Reengineering Aircraft Structural Life Prediction Using a Digital Twin

    OpenAIRE

    Eric J. Tuegel; Ingraffea, Anthony R.; Eason, Thomas G.; S. Michael Spottswood

    2011-01-01

    Reengineering of the aircraft structural life prediction process to fully exploit advances in very high performance digital computing is proposed. The proposed process utilizes an ultrahigh fidelity model of individual aircraft by tail number, a Digital Twin, to integrate computation of structural deflections and temperatures in response to flight conditions, with resulting local damage and material state evolution. A conceptual model of how the Digital Twin can be used for predicting the lif...

  20. Life Prediction of Composite Armor in an Unbonded Flexible Pipe

    OpenAIRE

    Loverich, James S.

    1997-01-01

    Composite materials are under consideration for the replacement of steel helical tendons in unbonded flexible pipes utilized by the offshore oil industry. Higher strength to weight ratios and increased corrosion resistance are the primary advantages of a composite material for this application. The current study focuses on the life prediction of a PPS/AS-4 carbon fiber composite proposed for the above employment....

  1. Survey on damage mechanics models for fatigue life prediction

    NARCIS (Netherlands)

    Silitonga, S.; Maljaars, J.; Soetens, F.; Snijder, H.H.

    2013-01-01

    Engineering methods to predict the fatigue life of structures have been available since the beginning of the 20th century. However, a practical problem arises from complex loading conditions and a significant concern is the accuracy of the methods under variable amplitude loading. This paper provide

  2. Describing and predicting the high temperature LCF life with the local equivalent strain energy approach

    International Nuclear Information System (INIS)

    The LESED approach is successful for describing and predicting the life of notched specimens for GH36 (iron-base superalloy) at 3000C. It is guessed that this approach may be better for the material with higher strain hardening capacity. It is found that Neuber's relationship is unsatisfactory for multiaxial stress state and especially under high stress/strain level. It appears that J-integral is also an effective parameter for describing the LCF life, but rather difficult for predicting the LCF life of notched specimens. (orig./HP)

  3. Advances in fatigue life prediction methodology for metallic materials

    Science.gov (United States)

    Newman, J. C., Jr.

    1992-01-01

    The capabilities of a plasticity-induced crack-closure model to predict small- and large-crack growth rates, and in some cases total fatigue life, for four aluminum alloys and three titanium alloys under constant-amplitude, variable-amplitude, and spectrum loading are described. Equations to calculate a cyclic-plastic-zone corrected effective stress-intensity factor range from a cyclic J-integral and crack-closure analysis of large cracks were reviewed. The effective stress-intensity factor range against crack growth rate relations were used in the closure model to predict small- and large-crack growth under variable-amplitude and spectrum loading. Using the closure model and microstructural features, a total fatigue life prediction method is demonstrated for three aluminum alloys under various load histories.

  4. High-temperature fatigue life prediction of turbopump turbine

    International Nuclear Information System (INIS)

    In general, many components are able to be operated under severe thermal conditions. The turbopump turbine is operated under these environments like high temperature and high centrifugal force due to high rotating velocity during operating time. Because these conditions may often cause low-cycle fatigue problem, strain life method is applied to predict low-cycle fatigue life of turbopump turbine. In this paper, strain life method is used to analyze low-cycle fatigue. First of all, to obtain strain history, thermal stress analysis is practised by ABAQUS/CAE. Considering elasticity and plasticity strain's effect, Coffin-Manson' equation is used. S.W.T's method is used to consider the mean stress effect. Low-cycle fatigue analysis is done for turbopump turbine which may have FCL(Fracture Critical Location). MSC.Fatigue is used to analyze low-cycle fatigue life of turbopump turbine.

  5. Predicting Bullying: Exploring the Contributions of Childhood Negative Life Experiences in Predicting Adolescent Bullying Behavior.

    Science.gov (United States)

    Connell, Nadine M; Morris, Robert G; Piquero, Alex R

    2016-07-01

    Although there has been much interest in research on aggression and in particular bullying, a relatively less charted area of research has centered on articulating a better understanding of the mechanisms and processes by which persons are at increased risk for bullying. Furthermore, those studies that have investigated the linkages between childhood experiences and bullying perpetration have been limited with respect to definitional and operational issues, reliance on cross-sectional data, and the lack of assessing competing explanations of bullying perpetration. Using five waves of data from a community-based longitudinal sample of children followed through age 18 (N = 763), the current study examines the extent to which childhood negative life events in a variety of domains predict adolescent bullying. Results show that early childhood experiences, particularly those within the family and school domains, may alter life trajectories and can act as predictors for later adolescent bullying, thereby underscoring the potential importance that relatively minor experiences can have over the long term. Implications for future research based on these analyses are examined. PMID:25759430

  6. Prediction based on mean subset

    DEFF Research Database (Denmark)

    Øjelund, Henrik; Brown, P. J.; Madsen, Henrik;

    2002-01-01

    Shrinkage methods have traditionally been applied in prediction problems. In this article we develop a shrinkage method (mean subset) that forms an average of regression coefficients from individual subsets of the explanatory variables. A Bayesian approach is taken to derive an expression of how...... the coefficient vectors from each subset should be weighted. It is not computationally feasible to calculate the mean subset coefficient vector for larger problems, and thus we suggest an algorithm to find an approximation to the mean subset coefficient vector. In a comprehensive Monte Carlo simulation study......, it is found that the proposed mean subset method has superior prediction performance than prediction based on the best subset method, and in some settings also better than the ridge regression and lasso methods. The conclusions drawn from the Monte Carlo study is corroborated in an example in which prediction...

  7. Life Prediction Issues in Thermal/Environmental Barrier Coatings in Ceramic Matrix Composites

    Science.gov (United States)

    Shah, Ashwin R.; Brewer, David N.; Murthy, Pappu L. N.

    2001-01-01

    Issues and design requirements for the environmental barrier coating (EBC)/thermal barrier coating (TBC) life that are general and those specific to the NASA Ultra-Efficient Engine Technology (UEET) development program have been described. The current state and trend of the research, methods in vogue related to the failure analysis, and long-term behavior and life prediction of EBCITBC systems are reported. Also, the perceived failure mechanisms, variables, and related uncertainties governing the EBCITBC system life are summarized. A combined heat transfer and structural analysis approach based on the oxidation kinetics using the Arrhenius theory is proposed to develop a life prediction model for the EBC/TBC systems. Stochastic process-based reliability approach that includes the physical variables such as gas pressure, temperature, velocity, moisture content, crack density, oxygen content, etc., is suggested. Benefits of the reliability-based approach are also discussed in the report.

  8. How the behavioral approach system predicts everyday life outcomes.

    Science.gov (United States)

    Izadikhah, Zahra; Jackson, Chris J

    2010-01-01

    This study tested crucial components of Gray's reinforcement sensitivity theory that have generally been overlooked in the literature. We tested whether the perceived amount of reward moderates the behavioral approach system (BAS) and the importance of reward mediates BAS in the prediction of job satisfaction and organizational commitment. Results from 514 participants employed in part-time and full-time jobs provided support for our model, such that the indirect effect of BAS through the importance of reward was strongest when reward was provided. This model advances our understanding of reinforcement sensitivity theory and offers a solid foundation for predicting outcomes in everyday life. PMID:20923087

  9. How the behavioral approach system predicts everyday life outcomes.

    Science.gov (United States)

    Izadikhah, Zahra; Jackson, Chris J

    2010-01-01

    This study tested crucial components of Gray's reinforcement sensitivity theory that have generally been overlooked in the literature. We tested whether the perceived amount of reward moderates the behavioral approach system (BAS) and the importance of reward mediates BAS in the prediction of job satisfaction and organizational commitment. Results from 514 participants employed in part-time and full-time jobs provided support for our model, such that the indirect effect of BAS through the importance of reward was strongest when reward was provided. This model advances our understanding of reinforcement sensitivity theory and offers a solid foundation for predicting outcomes in everyday life.

  10. Shelf life prediction of radiation sterilized polymeric materials

    International Nuclear Information System (INIS)

    The functional properties of many polymers employed in medical disposables are unaffected by sterilizing doses of ionizing radiation. However, some materials (PVC, polypropylene, cellulosics, etc.) undergo undesirable changes which continue to occur for the shelf life of the product. In many cases, conventional accelerated aging techniques do not accurately predict the real time properties of the materials. As real time aging is not generally practical, it has become necessary to develop accelerated aging techniques which can predict the functional properties of a material for the shelf life of the product. This presentation will address issues involved in developing these tests. Real time physical property data is compared to data generated by various acceleration methods. (author)

  11. Fracture Mechanics Prediction of Fatigue Life of Aluminum Highway Bridges

    DEFF Research Database (Denmark)

    Rom, Søren; Agerskov, Henning

    2015-01-01

    Fracture mechanics prediction of the fatigue life of aluminum highway bridges under random loading is studied. The fatigue life of welded joints has been determined from fracture mechanics analyses and the results obtained have been compared with results from experimental investigations....... The fatigue life of welded plate specimens has been investigated. Both the fracture mechanics analyses and the fatigue tests have been carried out using load histories, which correspond to one week's traffic loading, determined by means of strain gauge measurements on the deck structure of the Farø Bridges...... against fatigue in aluminum bridges, may give results which are unconservative. Furthermore, it was in both investigations found that the validity of the results obtained from Miner's rule will depend on the distribution of the load history in tension and compression....

  12. Patterns, Entropy, and Predictability of Human Mobility and Life

    OpenAIRE

    Shao-Meng Qin; Hannu Verkasalo; Mikael Mohtaschemi; Tuomo Hartonen; Mikko Alava

    2012-01-01

    Cellular phones are now offering an ubiquitous means for scientists to observe life: how people act, move and respond to external influences. They can be utilized as measurement devices of individual persons and for groups of people of the social context and the related interactions. The picture of human life that emerges shows complexity, which is manifested in such data in properties of the spatiotemporal tracks of individuals. We extract from smartphone-based data for a set of persons impo...

  13. Residual Useful Life Prediction for Electronic Component Based on ENN and UKF%基于 ENN 和 UKF 的电子部件剩余使用寿命预测

    Institute of Scientific and Technical Information of China (English)

    李文峰; 许爱强; 尹晋; 朱广辉

    2016-01-01

    A new method based on the methods of ensemble neural networks and unscented Kalman filter is proposed for predicting the residual useful life based on the unscented Kalman filter with unknown measurement noise under the condi -tion of partially observable information .Firstly ,in combination with the equipment performance degradation data ,a state of the group of observed data is generated ,and the bootstrap technique is used to construct of a plurality of groups of data ,the integrated neural network training state observation data sets are adopted to estimate the measurement noise optimal range according to the formula .Secondly ,the residual life prediction and probability density distribution of the nonlinear system are realized by embedding the standard error of measurement noise as the unknown parameters into the framework of un -scented Kalman filter lifetime prediction .Finally ,the validity and feasibility of the proposed method is verified by the simula-tion of the life of the lithiumion battery .%针对部分可观测信息条件下量测噪声未知时非线性滤波剩余寿命预测的问题,提出了一种基于集成神经网络(ENN)和无迹卡尔曼滤波(UKF)的寿命预测方法。首先,结合设备性能退化量测数据,生成状态-观测数据组,并利用bootstrap 技术构建多个数据组,采用集成神经网络训练状态-观测数据组,根据推导公式估计量测噪声标准差的最优取值范围;其次,将量测噪声标准差作为未知参数嵌入在无迹卡尔曼滤波寿命预测框架中,实现非线性系统的剩余寿命预测及概率密度分布;最后,选取电子部件锂电池进行寿命预测仿真验证了该方法的有效性和可行性。

  14. Prediction of the Service Life of a Reinforced Concrete Column under Chloride Environment

    OpenAIRE

    Mohammad K. Alkam; Maha Alqam

    2015-01-01

    In the present investigation, service life of a reinforced concrete column exposed to chloride environment has been predicted. This study has been based on numerical simulation of chloride ion diffusion in a concrete column during its anticipated life span. The simulation process has included the concrete cover replacement whenever chloride ion concentration has reached the critical threshold value at the reinforcement surface. Repair scheduling of the concrete column under consideration has ...

  15. Fatigue Life Prediction under Service Load Considering Strengthening Effect of Loads below Fatigue Limit

    Institute of Scientific and Technical Information of China (English)

    ZHAO Lihui; ZHENG Songlin; FENG Jinzhi

    2014-01-01

    Lightweight design requires an accurate life prediction for structures and components under service loading histories. However, predicted life with the existing methods seems too conservative in some cases, leading to a heavy structure. Because these methods are established on the basis that load cycles would only cause fatigue damage, ignore the strengthening effect of loads. Based on Palmgren-Miner Rule (PMR), this paper introduces a new method for fatigue life prediction under service loadings by taking into account the strengthening effect of loads below the fatigue limit. In this method, the service loadings are classified into three categories: damaging load, strengthening load and none-effect load, and the process for fatigue life prediction is divided into two stages: stage I and stage II, according to the best strengthening number of cycles. During stage I, fatigue damage is calculated considering both the strengthening and damaging effect of load cycles. While during stage II, only the damaging effect is considered. To validate this method, fatigue lives of automobile half shaft and torsion beam rear axle are calculated based on the new method and traditional methods, such as PMR and Modified Miner Rule (MMR), and fatigue tests of the two components are conducted under service loading histories. The tests results show that the percentage errors of the predicted life with the new method to mean life of tests for the two components are –3.78% and –1.76% separately, much lesser than that with PMR and MMR. By considering the strengthening effect of loads below the fatigue limit, the new method can significantly improve the accuracy for fatigue life prediction. Thus lightweight design can be fully realized in the design stage.

  16. Life prediction of advanced materials for gas turbine application

    Energy Technology Data Exchange (ETDEWEB)

    Zamrik, S.Y.; Ray, A.; Koss, D.A. [Pennsylvania State Univ., University Park, PA (United States)

    1995-10-01

    Most of the studies on the low cycle fatigue life prediction have been reported under isothermal conditions where the deformation of the material is strain dependent. In the development of gas turbines, components such as blades and vanes are exposed to temperature variations in addition to strain cycling. As a result, the deformation process becomes temperature and strain dependent. Therefore, the life of the component becomes sensitive to temperature-strain cycling which produces a process known as {open_quotes}thermomechanical fatigue, or TMF{close_quotes}. The TMF fatigue failure phenomenon has been modeled using conventional fatigue life prediction methods, which are not sufficiently accurate to quantitatively establish an allowable design procedure. To add to the complexity of TMF life prediction, blade and vane substrates are normally coated with aluminide, overlay or thermal barrier type coatings (TBC) where the durability of the component is dominated by the coating/substrate constitutive response and by the fatigue behavior of the coating. A number of issues arise from TMF depending on the type of temperature/strain phase cycle: (1) time-dependent inelastic behavior can significantly affect the stress response. For example, creep relaxation during a tensile or compressive loading at elevated temperatures leads to a progressive increase in the mean stress level under cyclic loading. (2) the mismatch in elastic and thermal expansion properties between the coating and the substrate can lead to significant deviations in the coating stress levels due to changes in the elastic modulii. (3) the {open_quotes}dry{close_quotes} corrosion resistance coatings applied to the substrate may act as primary crack initiation sites. Crack initiation in the coating is a function of the coating composition, its mechanical properties, creep relaxation behavior, thermal strain range and the strain/temperature phase relationship.

  17. Thermal barrier coating life-prediction model development

    Science.gov (United States)

    Strangman, T. E.; Neumann, J.; Liu, A.

    1986-01-01

    The program focuses on predicting the lives of two types of strain-tolerant and oxidation-resistant thermal barrier coating (TBC) systems that are produced by commercial coating suppliers to the gas turbine industry. The plasma-sprayed TBC system, composed of a low-pressure plasma-spray (LPPS) or an argon shrouded plasma-spray (ASPS) applied oxidation resistant NiCrAlY or (CoNiCrAlY) bond coating and an air-plasma-sprayed yttria partially stabilized zirconia insulative layer, is applied by both Chromalloy, Klock, and Union Carbide. The second type of TBS is applied by the electron beam-physical vapor deposition (EB-PVD) process by Temescal. The second year of the program was focused on specimen procurement, TMC system characterization, nondestructive evaluation methods, life prediction model development, and TFE731 engine testing of thermal barrier coated blades. Materials testing is approaching completion. Thermomechanical characterization of the TBC systems, with toughness, and spalling strain tests, was completed. Thermochemical testing is approximately two-thirds complete. Preliminary materials life models for the bond coating oxidation and zirconia sintering failure modes were developed. Integration of these life models with airfoil component analysis methods is in progress. Testing of high pressure turbine blades coated with the program TBS systems is in progress in a TFE731 turbofan engine. Eddy current technology feasibility was established with respect to nondestructively measuring zirconia layer thickness of a TBC system.

  18. 基于断裂力学方法的粉末盘低周疲劳寿命预测%Fracture Mechanics Method Based LCF Life Prediction for Powder Metallurgy Disks

    Institute of Scientific and Technical Information of China (English)

    任远; 张成成; 高靖云; 李孟光

    2016-01-01

    The traditional life prediction methods lack the consideration for inclusion influence in powder metal-lurgy ( PM) . To overcome this shortcoming, the computational fracture mechanics is used to simulate the propaga-tion process, which ranges from initial size to detectable size, of an inclusion-induced defect in a PM labyrinth seal disk. The number of cycles corresponding to the propagation process is considered as the crack initiation life. The initiation life of the crack originating from the initial inclusion is 1639 cycles when using the modification model of crack growth rate for small cracks, and the result is 4956 cycles if the modification model is not adopted. It indi-cates that ignoring the “small crack effect” can lead to a dangerous estimate of crack initiation life. Furthermore, the establishment of crack-embedded finite element models and the chosen of integration path for crack propagation life estimation are also discussed. Fracture mechanics based crack propagation life prediction needs many repeated finite element calculations and smoothing treatments for crack fronts, so it is time consuming and labor intensive. However, its advantage in precise and quantitative analysis makes it a favorable supplement to current methods and it is helpful when determining the time between overhauls for life-limited parts.%为克服传统寿命预测未能考虑粉末合金夹杂物的缺陷,在某粉末封严盘定寿过程中,使用计算断裂力学方法模拟了夹杂缺陷从初始状态一直增大到可检尺度的扩展过程,并将该过程经历的循环数作为裂纹萌生寿命。在考虑小裂纹扩展速率修正的情况下萌生寿命为1639循环,若不采用修正则为4956循环,说明忽略“小裂纹效应”会得出偏于危险的萌生寿命计算结果。对含裂纹有限元模型的建立、裂纹扩展寿命计算中积分路径的选取等问题进行了讨论。使用断裂力学方法预测裂纹萌生寿命需要

  19. Low-Cycle Fatigue Life Prediction in GTD-111 Superalloy at Elevated Temperatures

    International Nuclear Information System (INIS)

    The Ni-base super-heat-resistant alloy, GTD-111, is employed in gas turbines because of its high temperature strength and oxidation resistance. It is important to predict the fatigue life of this superalloy in order to improve the efficiency of gas turbines. In this study, low-cycle fatigue tests are performed as variables of total strain range and temperature. The relationship between the strain energy density and number of cycles to failure is examined in order to predict the low-cycle fatigue life of the GTD-111 superalloy. The fatigue life predicted by using the strain-energy methods is found to coincide with that obtained from the experimental data and from the Coffin-Manson method

  20. Low-Cycle Fatigue Life Prediction in GTD-111 Superalloy at Elevated Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ho Young; Kim, Jae Hoon [Chungnam National University, Daejeon (Korea, Republic of); Yoo, Keun Bong; Lee, Han Sang [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); You, Young Soo [Korea Institute of Materials Science, Changwon (Korea, Republic of)

    2011-07-15

    The Ni-base super-heat-resistant alloy, GTD-111, is employed in gas turbines because of its high temperature strength and oxidation resistance. It is important to predict the fatigue life of this superalloy in order to improve the efficiency of gas turbines. In this study, low-cycle fatigue tests are performed as variables of total strain range and temperature. The relationship between the strain energy density and number of cycles to failure is examined in order to predict the low-cycle fatigue life of the GTD-111 superalloy. The fatigue life predicted by using the strain-energy methods is found to coincide with that obtained from the experimental data and from the Coffin-Manson method.

  1. A computational approach for thermomechanical fatigue life prediction of dissimilarly welded superheater tubes

    Energy Technology Data Exchange (ETDEWEB)

    Krishnasamy, Ram-Kumar; Seifert, Thomas; Siegele, Dieter [Fraunhofer-Institut fuer Werkstoffmechanik (IWM), Freiburg im Breisgau (Germany)

    2010-07-01

    In this paper a computational approach for fatigue life prediction of dissimilarly welded superheater tubes is presented and applied to a dissimilar weld between tubes made of the nickel base alloy Alloy617 tube and the 12% chromium steel VM12. The approach comprises the calculation of the residual stresses in the welded tubes with a multi-pass dissimilar welding simulation, the relaxation of the residual stresses in a post weld heat treatment (PWHT) simulation and the fatigue life prediction using the remaining residual stresses as initial condition. A cyclic fiscoplasticity model is used to calculate the transient stresses and strains under thermocyclic service loadings. The fatigue life is predicted with a damage parameter which is based on fracture mechanics. The adjustable parameters of the model are determined based on LCF and TMF experiments. The simulations show, that the residual stresses that remain after PWHT further relax in the first loading cycles. The predicted fatigue lives depend on the residual stresses and, thus, on the choice of the loading cycle in which the damage parameter is evaluated. It the first loading cycle, where residual stresses are still present, is considered, lower fatigue lives are predicted compared to predictions considering loading cycles with relaxed residual stresses. (orig.)

  2. Carbonation life prediction of service reinforced concrete bridge based on reliability theory of durability%基于可靠性原理的在役钢筋混凝土桥梁碳化寿命预测

    Institute of Scientific and Technical Information of China (English)

    甘海龙; 谢肖礼

    2013-01-01

    友爱立交桥是南宁市快速环道重要的交通枢纽,对其进行耐久性评估和寿命预测对于桥梁的正常运营具有重要的意义.对桥梁进行了外观检测、混凝土回弹检测、混凝土保护层厚度检测、混凝土碳化深度检测,以及混凝土氯离子含量检测,并对检测结果进行统计与分析.基于桥梁服役的大气环境参数及检测数据,分析并计算了桥梁主要受力构件的碳化可靠指标及剩余碳化寿命,为评定桥梁的服役年限及加固维修提供了参考依据.%The Youai grade separation bridge is a transportation hub of nanning fast ring road, and the durability evaluation and life prediction of the bridge is extremely significant for ensuring the normal operation of the bridge. The youai grade separation bridge on the appearance test, concrete rebound detection, concrete cover depth detection, concrete carbonation depth detection, concrete chlorine ion content detection,and the detection results in statistics and analysis. Based on the bridge of the service the atmospheric environment parameters and testing data,the paper calculates and analyzes the main stress components the carbonation bridge reliability index and remaining life of carbide, assessing the bridge for the service life and reinforcement maintenance and offer the scientific basis.

  3. Prediction of corrosion fatigue life using DCPD method

    International Nuclear Information System (INIS)

    In order to develop a method of corrosion fatigue design and estimate reliability of TMCP steel using as the material of heavy industries and plants, its corrosion susceptibilities and corrosion fatigue life considering corrosion degradation were investigated. From the results, the corrosion characteristic of TMCP steel is very susceptible in 3.5wt.% NaCl solution. Its susceptibility was linearly increased with the solution temperature increase. The potential difference due to the crack growth behavior in 25 deg. C, 3.5wt.% NaCl solution is very susceptible. And it was found that stress amplitude has a linear relationship with the critical potential. Therefore, it is expected that the corrosion fatigue life of TMCP steel can be nondestructively predicted using the DCPD method

  4. Using ABAQUS Scripting Interface for Materials Evaluation and Life Prediction

    Science.gov (United States)

    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.

  5. Life histories predict vulnerability to overexploitation in parrotfishes

    Science.gov (United States)

    Taylor, Brett M.; Houk, Peter; Russ, Garry R.; Choat, J. Howard

    2014-12-01

    A scarcity of life-history data currently exists for many exploited coral reef fishes, hindering our ability to interpret fishery dynamics and develop sound conservation policies. In particular, parrotfishes (Family Labridae) represent a ubiquitous and ecologically important group that is increasingly prevalent in commercial and artisanal fisheries worldwide. We used both fishery-dependent and fishery-independent data to examine the effect of life histories on vulnerability to overexploitation in parrotfishes. Vulnerability for each species was derived from independent measures associated with both temporal (20-year catch records) and spatial datasets. Most life-history traits examined were significant predictors of vulnerability across species, but their relative utility differed considerably. Length-based traits (e.g., lengths at maturity and sex change, maximum length) were generally superior to age-based traits (e.g., life span), but one age-based trait, age at female maturation, was the best predictor. The results suggest that easily derived metrics such as maximum length can be effective measures of sensitivity to exploitation when applied to phylogenetically related multispecies assemblages, but more holistic and comprehensive age-based demographic data should be sought, especially in data-deficient and heavily impacted regions. Given the increasing prevalence of parrotfishes in the global coral reef harvest, species-specific responses demonstrate the capacity for heavy fishing pressure to alter parrotfish assemblages considerably.

  6. Void damage model and service life prediction for solid high polymer

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the analysis of three void damage variety models, this note presents ( i ) a method that regards the void content as a damage variation of the grain and ( ii ) a geometric model for micro-unit of void damage. Equations of the void damage variety containing void content are analyzed. This work is focused on the measurement of internal damage level and the damage variety estimation is directly related to the life predication in the practical engineering applications. Nowadays, the critical service life of the solid grain/polymers is usually presumed at domestic and international level. The strength or strain reduction of 20%or the stabilizer consumption of 50% is generally regarded as a critical storage life of the solid grain/polymers, and the service life is predicted by the extrapolation method on Anhenius formula. The applications, however, show that the above method is unreliable and has significant errors. With the aid of the discontiguous automatic measuring device of real time volume deformation and void content, the master curve of void damage variety, the storage service life and the surplus life of a solid rocket grain are obtained. Since the critical storage life has been measured, and the accuracy of the service life prediction has been greatly increased. It is a novel ideal and a break-through technique.

  7. Mechanical performance and life prediction for canister copper

    Energy Technology Data Exchange (ETDEWEB)

    Rantala, J.; Auerkari, P.; Salonen, J.; Holmstroem, S.; Laukkanen, A. (VTT Technical Research Centre of Finland, Espoo (Finland)); Saukkonen, T. (Aalto Univ. School of Science and Technology, Espoo (Finland))

    2010-05-15

    The creep response of the OFP copper at 175 deg C has been studied by uniaxial, multiaxial creep testing, metallography and surface inspections. Surface cracks have been observed in a uniaxial test which has been running for more than 70 000 h (eight years). In a CT-specimen creep cavities have been observed after an exposure of 25 000 h. A purpose-built creep strain model has been implemented into FE analysis to characterize the stress multiaxiality and the stress state of the CT specimen. The results have been applied for life prediction of copper at foreseen levels of stress and temperature at the repository. (orig.)

  8. Fatigue life prediction of crankshaft repaired by twin arc spraying

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-qing; WANG Cheng-tao; PU Geng-qiang

    2005-01-01

    This paper used Baumel Jr. and Seeger's approach estimating fatigue parameters of 48MnV with 3Cr13coatings. The fatigue life of the crankshaft of a six-cylinder engine, repaired by twin arc spraying 3cr13 deposits, is respectively calculated using different damage model such as S-N method, normal strain approaches, SWT-Bannantine approaches, shear strain approaches, and fatemi-Socie method based on dynamical simulation and FE analysis of crankshaft. The results indicate that the traditional calculation is conservative and that the life of crankshaft repaired by arc spraying is sufficient.

  9. Predicting Method of Concrete Service Life Based on Damage Development Equation%基于损伤演化方程的混凝土寿命预测方法

    Institute of Scientific and Technical Information of China (English)

    余红发; 孙伟; 麻海燕; 张云升; 缪昌文; 金祖权; 刘建忠

    2012-01-01

    Based on the damage development equation of concrete subjected to freezing-thawing cycles or chemical attacks, a systematic theory and the basic operation for the prediction on service life of concrete structure were presented. Validity of the damage development equation of concrete was established by the vast data obtained through single factor. Service life prediction of some national key projections, such as the potassic manure plant in salt lake of Qinghai and Beijing Cloverleaf Bridge, were studied by specially designed durability experiments, which included single factor (salt lake bittern attack), double factor (wet-dry cycles compound with salt lake bittern attack), 3. 5% mass concentration NaCl solution salt-frost experiments. Results show that either ordinary Portland cement concrete or high strength concrete is not applicable to the potassic manure plant in salt lake of Qinghai. Service life of Beijing Cloverleaf Bridge can also meet the requirements of 50 years since C60 air-entrained high performance concrete subjected to salt-frost action are adopted.%基于混凝土的冻融或腐蚀损伤演化方程,提出了一套预测混凝土结构使用寿命的基本方法与理论体系;用单一冻融因素作用下的大量试验数据验证了混凝土的损伤演化方程;通过专门设计的盐湖卤水腐蚀单一因素和(干湿循环+盐湖卤水腐蚀)双重因素、3.5%质量浓度的NaCl盐冻试验,研究了青海盐湖钾肥和北京城市立交桥主体结构混凝土的使用寿命预测问题.结果表明:青海盐湖钾肥工程不宜采用普通混凝土和高强混凝土;C60引气高性能混凝土在盐冻作用下满足北京城市立交桥50年的使用要求.

  10. Fatigue Life Analysis of Rolling Bearings Based on Quasistatic Modeling

    OpenAIRE

    Wei Guo; Hongrui Cao; Zhengjia He; Laihao Yang

    2015-01-01

    Rolling bearings are widely used in aeroengine, machine tool spindles, locomotive wheelset, and so forth. Rolling bearings are usually the weakest components that influence the remaining life of the whole machine. In this paper, a fatigue life prediction method is proposed based on quasistatic modeling of rolling bearings. With consideration of radial centrifugal expansion and thermal deformations on the geometric displacement in the bearings, the Jones’ bearing model is updated, which can pr...

  11. Personality Predicts Health Declines Through Stressful Life Events During Late Mid-Life.

    Science.gov (United States)

    Iacovino, Juliette M; Bogdan, Ryan; Oltmanns, Thomas F

    2016-08-01

    Personality predicts the occurrence of dependent stressful life events (SLE; i.e., events reliant, at least in part, on an individual's behavior). This process, termed stress generation, contributes to psychiatric outcomes, but its role in physical health is unknown. Data were included from 998 participants (aged 55-64) in the St. Louis Personality and Aging Network (SPAN) study. Assessments occurred every 6 months for 18 months. Neuroticism, impulsivity, and agreeableness were measured with the Revised NEO Personality Inventory. Dependent (e.g., divorce) and independent (e.g., family death) SLE occurring within 6 months following baseline were assessed with the List of Threatening Experiences and confirmed by interviews. Health problems occurring within a year after SLE were the outcome. Analyses examined whether neuroticism, impulsivity, and agreeableness indirectly predict the onset of new health problems through exposure to dependent SLE. Each personality trait was associated with dependent, but not independent, SLE. Only dependent SLE predicted new health problems. Each personality trait indirectly predicted the onset of new health problems through dependent SLE. Findings suggest that personality-driven stress generation influences physical health during late mid-life. Addressing personality in interventions may reduce the occurrence of SLE, in turn decreasing health risks. PMID:25929195

  12. Fatigue life prediction of fiber reinforced concrete under flexural load

    DEFF Research Database (Denmark)

    Zhang, Jun; Stang, Henrik; Li, Victor

    1999-01-01

    This paper presents a semi-analytical method to predict fatigue behavior in flexure of fiber reinforced concrete (FRC) based on the equilibrium of force in the critical cracked section. The model relies on the cyclic bridging law, the so-called stress-crack width relationship under cyclic tensile...

  13. Stress analysis and life prediction of gas turbine blade

    Science.gov (United States)

    Hsiung, H. C.; Dunn, A. J.; Woodling, D. R.; Loh, D. L.

    1988-01-01

    A stress analysis procedure is presented for a redesign of the Space Shuttle Main Engine high pressure fuel turbopump turbine blades. The analysis consists of the one-dimensional scoping analysis to support the design layout and the follow-on three-dimensional finite element analysis to confirm the blade design at operating loading conditions. Blade life is evaluated based on high-cycle fatigue and low-cycle fatigue.

  14. Condition-based prediction of time-dependent reliability in composites

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper presents a reliability-based prediction methodology to obtain the remaining useful life of composite materials subjected to fatigue degradation....

  15. A Simple Fatigue Life Prediction Algorithm Using the Modified NASGRO Equation

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2016-01-01

    Full Text Available A simple fatigue life prediction algorithm using the modified NASGRO equation is proposed in this paper. The NASGRO equation is modified by introducing the concept of intrinsic effective threshold stress intensity factor (SIF range ΔKeffth. One advantage of the proposed method is that the complex growth behavior analysis of small cracks can be avoided, and then the fatigue life can be calculated by directly integrating the crack growth model from the initial defect size to the critical crack size. The fatigue limit and the intrinsic effective threshold SIF range ΔKeffth are used to calculate the initial defect size or initial flaw size. The value of ΔKeffth is determined by extrapolating the crack propagation rate curves. Instead of using the fatigue limit determined by the fatigue strength at the specific fatigue life, the fatigue limit is selected based on the horizontal tendency of the S-N curve. The calculated fatigue lives are compared to the experimental data of two different alloys. The predicted S-N curves agree with the test data well. Besides, the prediction results are compared with that calculated using the FASTRAN code. Results indicate that the proposed life prediction algorithm is simple and efficient.

  16. 基于腐败微生物的低温肉制品货架期预测研究进展%Advances on Shelf-life Prediction of Low-temperature Meat Products Based on Spoilage Microorganisms

    Institute of Scientific and Technical Information of China (English)

    贺旺林; 俞龙浩

    2015-01-01

    Some fungal spores,bacterial spore and thermal tolerant bacteria still survived in low-temperature meat products after thermal processing,which might cause low-temperature meat products spoilage. The technology of shelf-life prediction could effectively predict and monitor the shelf-life meat products,thereby reduce the production loss of industry and provide the food security of consumers. The microflora analysis,the growing pattern of specific spoilage organisms,the development of shelf-life prediction model and the validation and improvement of the model were reviewed in this paper,which provided the reference for the shelf-life prediction of the low-temperature meat products.%低温肉制品经热加工工序后仍残存真菌孢子、细菌芽孢和部分耐热细菌,极易发生腐败变质。货架期预测技术能够有效地预测和监控制品的货架期,从而减少生产企业的经济损失,并为消费者提供安全保障。综述了货架期预测过程中菌相分析、特定腐败菌生长模型建立、货架期预测软件开发和对模型的验证及改良等主要技术及其应用现状,为低温肉制品货架期预测和确定提供参考。

  17. 基于腐败微生物的低温肉制品货架期预测研究进展%Advances on Shelf-life Prediction of Low-temperature Meat Products Based on Spoilage Microorganisms

    Institute of Scientific and Technical Information of China (English)

    贺旺林; 俞龙浩

    2015-01-01

    低温肉制品经热加工工序后仍残存真菌孢子、细菌芽孢和部分耐热细菌,极易发生腐败变质。货架期预测技术能够有效地预测和监控制品的货架期,从而减少生产企业的经济损失,并为消费者提供安全保障。综述了货架期预测过程中菌相分析、特定腐败菌生长模型建立、货架期预测软件开发和对模型的验证及改良等主要技术及其应用现状,为低温肉制品货架期预测和确定提供参考。%Some fungal spores,bacterial spore and thermal tolerant bacteria still survived in low-temperature meat products after thermal processing,which might cause low-temperature meat products spoilage. The technology of shelf-life prediction could effectively predict and monitor the shelf-life meat products,thereby reduce the production loss of industry and provide the food security of consumers. The microflora analysis,the growing pattern of specific spoilage organisms,the development of shelf-life prediction model and the validation and improvement of the model were reviewed in this paper,which provided the reference for the shelf-life prediction of the low-temperature meat products.

  18. The analysis of random effects regression model for predicting the shelf-life of gun propellant

    OpenAIRE

    Chang, Wei-Te

    1995-01-01

    Most gun propellant is stored at depots for a long time before it is used. While being stored, the quality of the gun propellant may deteriorate and become unstable. In an attempt to avoid disaster due to use of unstable gun propellant, accurate prediction of the safe shelf-life of gun propellant is necessary. The shelf-life estimation methods used currently for a group of similar gun propellant lots are based on a fixed effects regression model. This does not take into consideration the fact...

  19. The prediction technology study of fatigue life for key parts of a tracked vehicle's suspension system

    Institute of Scientific and Technical Information of China (English)

    WANG Hongyan; RUI Qiang; HE Xiaojun

    2007-01-01

    In allusion to fatigue life of a tracked vehicle torsion bar, a virtual prototype model of the tracked vehicle suspension system including a flexible torsion bar was built based on dynamic simulation software-ADAMS. Node force and stress results of the torsion bar from last step simu- lation were acquired; taking into account the material charac- teristics and influential factors, fatigue life of the flexible body. of the torsion bar was predicted. Engineering results can be acquired through the contrast of the result of virtual test and statistical fatigue.

  20. Predicting Education Effects on Entrepreneur’s Strategic Choices and Life Quality

    Directory of Open Access Journals (Sweden)

    Tarja Niemela

    2015-11-01

    Full Text Available We demonstrate four models in prediction of the dependencies between entrepreneurs’ education, developmental intentions and perception of quality of life based on survey data (2012, n=460. Entrepreneurs with the higher level of education were more likely to maintain the current production line, plan pluriactive businesses and consider wage income and cooperation more important than others. Similarly, entrepreneurs with lower level of education experienced more often problems to cope with current and future farm work with existing resources. To conclude, spouses’ education seems to influence farm’s choices and quality of life. Implications for human capital theory and entrepreneurship education emerged.

  1. Patterns, entropy, and predictability of human mobility and life

    CERN Document Server

    Qin, Shao-Meng; Mohtaschemi, Mikael; Hartonen, Tuomo; Alava, Mikko

    2012-01-01

    Cellular phones are now offering an ubiquitous means for scientists to observe life: how people act, move and respond to external influences. They can be utilized as measurement devices of individual persons and for groups of people of the social context and the related interactions. The picture of human life that emerges shows complexity, which is manifested in such data in properties of the spatiotemporal tracks of individuals. We extract from smartphone-based data for a set of persons important locations such as "home", "work" and so forth over fixed length time-slots covering the days in the data-set. This set of typical places is heavy-tailed, a power-law distribution with an exponent close to -1.7. To analyze the regularities and stochastic features present, the days are classified for each person into regular, personal patterns. To this are superimposed fluctuations for each day. This randomness is measured by "life" entropy, computed both before and after finding the clustering so as to subtract the c...

  2. Assessment of residual life and prediction of further safe operation of selected elements of high-pressure boilers

    Energy Technology Data Exchange (ETDEWEB)

    Dobrzanski, J.; Zebik, F.; Milinski, P.

    1986-01-01

    Service life of boilers in coal-fired power plants in Poland is increasing; in many cases, service life of various equipment types exceeds the designed service life. Problems associated with testing equipment with a service life exceeding 100,000 h (12 years) are discussed. The following methods for predicting the safe service life of pressure vessels operating under high-temperature conditions are discussed: a nondestructive calculation method, a method based on creep tests of materials (creep rate and time to failure under conditions close to operating conditions), a method based on fatigue test results (time to equipment failure under conditions of high temperature and constant strain amplitude). Recommendations for prediction of further safe service life of steam boilers and steam pipes are made. 15 refs.

  3. Predicting Education Effects on Entrepreneur’s Strategic Choices and Life Quality

    OpenAIRE

    Tarja Niemela

    2015-01-01

    We demonstrate four models in prediction of the dependencies between entrepreneurs’ education, developmental intentions and perception of quality of life based on survey data (2012, n=460). Entrepreneurs with the higher level of education were more likely to maintain the current production line, plan pluriactive businesses and consider wage income and cooperation more important than others. Similarly, entrepreneurs with lower level of education experienced more often problems to cope with cur...

  4. 基于品质衰变理论的食品货架期预测模型及其应用研究进展%Advances in Predictive Shelf Life Models Based on Food Quality Deterioration Theory and Their Applications

    Institute of Scientific and Technical Information of China (English)

    史波林; 赵镭; 支瑞聪

    2012-01-01

    食品货架期是厂商对产品质量的承诺,也是消费者关心的质量要求。针对目前研究中货架期预测模型使用的随意性与不规范性,本文剖析货架食品的品质影响因素,明确感官、化学、物理和微生物4个货架期食品品质评价途径,分析所对应的货架食品品质衰变机理和货架寿命终点检测方法,归纳与总结现有货架预测常用模型和算法,形成基于品质衰变原理的货架期预测模型建立体系,并对该技术未来发展方向进行展望。%The shelf life of foods is not only the quality guarantee from manufacturers,but also the quality requirements from consumers.In view of arbitrary and improper use of predictive shelf life models,we herein analyze factors that influence the shelf life of foods,identify sensory,chemical,physical and microbiological properties as four aspects of food quality for shelf life prediction,explore the corresponding quality deterioration mechanisms and detection methods for the end of shelf life,summarize common predictive shelf life models and algorithms and develop new predictive shelf life models based on food quality deterioration theory.Meanwhile,further directions for research on shelf life prediction of foods are discussed.

  5. Ways that Social Change Predicts Personal Quality of Life

    Science.gov (United States)

    Cheung, Chau-Kiu; Leung, Kwok

    2010-01-01

    A notable way that social change affects personal quality of life would rely on the person's experience with social change. This experience may influence societal quality of life and quality of work life, which may in turn affect personal quality of life. Additionally, the experience of social change is possibly less detrimental to personal…

  6. Synthetic Microstructure-Based Lifing of Nickel-Based Superalloys

    Science.gov (United States)

    Tucker, Joseph C.

    This work focuses on the root cause of life limiting behavior in Ni-based superalloys for high pressure and temperature turbine disks applications in low cycle fatigue (LCF) by generating statistical volume elements (SVEs) of directly measured 3D microstructures for finite element method (FEM) simulations with crystal plasticity. Synthetic microstructures with experimentally determined microstructurally small fatigue crack (MSFC) weakest link features of as large as (ALA) grains and long annealing twins comprise the test cases. Upper limit truncated log-normal distributions account for the log-normal upper tail departure in grain size distributions of Ni-based superalloys more accurately representing ALA grains. Probability plots quantify the log-normality of grain sizes more effectively than traditional histograms. Twins are inserted into synthetic microstructures according to the coherent Sigma3 orientation relationship. A 3D measured dataset of the Inconel 100 (IN100) validates the Saltykov method stereology technique for estimating 3D grain size distributions from 2D; the 3D grain size distribution mean field and upper tail of IN100 is accurately predicted. The Saltykov method gave 3D grain sizes from a Rene 88 Damage Tolerant (R88DT) 2D dataset resulting in fatigue SVEs of approximately 1.5 million elements and 200 grains from FEM sensitivity studies. Changing mesh resolution minimally impacted global damage response, but converging locally requires significantly higher refinement. Fatigue interrogating FEM studies evolved hot spots in the local MSFC environment in one SVE, but not in another SVE with different crystallographic orientations, suggesting strong 3D full-field neighbor effects. The study revealed a need for slip line length considerations in crystal plasticity to better capture life limiting behavior. The findings point towards strictly limiting the ALA grain size in Ni-based superalloys to extend service life.

  7. Research on Service Life Prediction Model of Thrust Needle Bearing

    Directory of Open Access Journals (Sweden)

    Li Wei

    2012-11-01

    Full Text Available Needle roller thrust bear is small in size and of high ability in load bearing, therefore it is widely used in fields of aviation and automobile etc.  But the relation between their service life and pre-tightening torque is not very clear, so the using design of the bear depends mainly on experience of engineer, because of lack of references. In the paper, the theoretical analysis on relation between torque and load is done, special wearing test instrument is developed and wearing test of thrust needle bear is conducted. Based on the results of the test, mathematical model of relation between the losing amount of pre-tightening torque and the pre-tightening torque is built, based on which use of the bear in engineering will be more reasonable, and their pre-tightening torque will be given more accurately.

  8. Method and apparatus to predict the remaining service life of an operating system

    Science.gov (United States)

    Greitzer, Frank L.; Kangas, Lars J.; Terrones, Kristine M.; Maynard, Melody A.; Pawlowski, Ronald A. , Ferryman; Thomas A.; Skorpik, James R.; Wilson, Bary W.

    2008-11-25

    A method and computer-based apparatus for monitoring the degradation of, predicting the remaining service life of, and/or planning maintenance for, an operating system are disclosed. Diagnostic information on degradation of the operating system is obtained through measurement of one or more performance characteristics by one or more sensors onboard and/or proximate the operating system. Though not required, it is preferred that the sensor data are validated to improve the accuracy and reliability of the service life predictions. The condition or degree of degradation of the operating system is presented to a user by way of one or more calculated, numeric degradation figures of merit that are trended against one or more independent variables using one or more mathematical techniques. Furthermore, more than one trendline and uncertainty interval may be generated for a given degradation figure of merit/independent variable data set. The trendline(s) and uncertainty interval(s) are subsequently compared to one or more degradation figure of merit thresholds to predict the remaining service life of the operating system. The present invention enables multiple mathematical approaches in determining which trendline(s) to use to provide the best estimate of the remaining service life.

  9. Fatigue Life Analysis of Rolling Bearings Based on Quasistatic Modeling

    Directory of Open Access Journals (Sweden)

    Wei Guo

    2015-01-01

    Full Text Available Rolling bearings are widely used in aeroengine, machine tool spindles, locomotive wheelset, and so forth. Rolling bearings are usually the weakest components that influence the remaining life of the whole machine. In this paper, a fatigue life prediction method is proposed based on quasistatic modeling of rolling bearings. With consideration of radial centrifugal expansion and thermal deformations on the geometric displacement in the bearings, the Jones’ bearing model is updated, which can predict the contact angle, deformation, and load between rolling elements and bearing raceways more accurately. Based on Hertz contact theory and contact mechanics, the contact stress field between rolling elements and raceways is calculated. A coupling model of fatigue life and damage for rolling bearings is given and verified through accelerated life test. Afterwards, the variation of bearing life is investigated under different working conditions, that is, axial load, radial load, and rotational speed. The results suggested that the working condition had a great influence on fatigue life of bearing parts and the order in which the damage appears on bearing parts.

  10. Renal parenchymal histopathology predicts life-threatening chronic kidney disease as a result of radical nephrectomy.

    Science.gov (United States)

    Sejima, Takehiro; Honda, Masashi; Takenaka, Atsushi

    2015-01-01

    The preoperative prediction of post-radical nephrectomy renal insufficiency plays an important role in the decision-making process regarding renal surgery options. Furthermore, the prediction of both postoperative renal insufficiency and postoperative cardiovascular disease occurrence, which is suggested to be an adverse consequence caused by renal insufficiency, contributes to the preoperative policy decision as well as the precise informed consent for a renal cell carcinoma patient. Preoperative nomograms for the prediction of post-radical nephrectomy renal insufficiency, calculated using patient backgrounds, are advocated. The use of these nomograms together with other types of nomograms predicting oncological outcome is beneficial. Post-radical nephrectomy attending physicians can predict renal insufficiency based on the normal renal parenchymal pathology in addition to preoperative patient characteristics. It is suggested that a high level of global glomerulosclerosis in nephrectomized normal renal parenchyma is closely associated with severe renal insufficiency. Some studies showed that post-radical nephrectomy severe renal insufficiency might have an association with increased mortality as a result of cardiovascular disease. Therefore, such pathophysiology should be recognized as life-threatening, surgically-related chronic kidney disease. On the contrary, the investigation of the prediction of mild post-radical nephrectomy renal insufficiency, which is not related to adverse consequences in the postoperative long-term period, is also promising because the prediction of mild renal insufficiency might be the basis for the substitution of radical nephrectomy for nephron-sparing surgery in technically difficult or compromised cases. The deterioration of quality of life caused by post-radical nephrectomy renal insufficiency should be investigated in conjunction with life-threatening matters.

  11. Life-history traits predict perennial species response to fire in a desert ecosystem.

    Science.gov (United States)

    Shryock, Daniel F; DeFalco, Lesley A; Esque, Todd C

    2014-08-01

    The Mojave Desert of North America has become fire-prone in recent decades due to invasive annual grasses that fuel wildfires following years of high rainfall. Perennial species are poorly adapted to fire in this system, and post-fire shifts in species composition have been substantial but variable across community types. To generalize across a range of conditions, we investigated whether simple life-history traits could predict how species responded to fire. Further, we classified species into plant functional types (PFTs) based on combinations of life-history traits and evaluated whether these groups exhibited a consistent fire-response. Six life-history traits varied significantly between burned and unburned areas in short (up to 4 years) or long-term (up to 52 years) post-fire datasets, including growth form, lifespan, seed size, seed dispersal, height, and leaf longevity. Forbs and grasses consistently increased in abundance after fire, while cacti were reduced and woody species exhibited a variable response. Woody species were classified into three PFTs based on combinations of life-history traits. Species in Group 1 increased in abundance after fire and were characterized by short lifespans, small, wind-dispersed seeds, low height, and deciduous leaves. Species in Group 2 were reduced by fire and distinguished from Group 1 by longer lifespans and evergreen leaves. Group 3 species, which also decreased after fire, were characterized by long lifespans, large non-wind dispersed seeds, and taller heights. Our results show that PFTs based on life-history traits can reliably predict the responses of most species to fire in the Mojave Desert. Dominant, long-lived species of this region possess a combination of traits limiting their ability to recover, presenting a clear example of how a novel disturbance regime may shift selective environmental pressures to favor alternative life-history strategies. PMID:25247062

  12. Life-history traits predict perennial species response to fire in a desert ecosystem

    Science.gov (United States)

    Shryock, Daniel F.; DeFalco, Lesley A.; Esque, Todd C.

    2014-01-01

    The Mojave Desert of North America has become fire-prone in recent decades due to invasive annual grasses that fuel wildfires following years of high rainfall. Perennial species are poorly adapted to fire in this system, and post-fire shifts in species composition have been substantial but variable across community types. To generalize across a range of conditions, we investigated whether simple life-history traits could predict how species responded to fire. Further, we classified species into plant functional types (PFTs) based on combinations of life-history traits and evaluated whether these groups exhibited a consistent fire-response. Six life-history traits varied significantly between burned and unburned areas in short (up to 4 years) or long-term (up to 52 years) post-fire datasets, including growth form, lifespan, seed size, seed dispersal, height, and leaf longevity. Forbs and grasses consistently increased in abundance after fire, while cacti were reduced and woody species exhibited a variable response. Woody species were classified into three PFTs based on combinations of life-history traits. Species in Group 1 increased in abundance after fire and were characterized by short lifespans, small, wind-dispersed seeds, low height, and deciduous leaves. Species in Group 2 were reduced by fire and distinguished from Group 1 by longer lifespans and evergreen leaves. Group 3 species, which also decreased after fire, were characterized by long lifespans, large non-wind dispersed seeds, and taller heights. Our results show that PFTs based on life-history traits can reliably predict the responses of most species to fire in the Mojave Desert. Dominant, long-lived species of this region possess a combination of traits limiting their ability to recover, presenting a clear example of how a novel disturbance regime may shift selective environmental pressures to favor alternative life-history strategies.

  13. Weibull分布下基于MLE的红外发光二极管寿命预测%Life Prediction for Infrared LED Based on MLE under Weibull Distribution

    Institute of Scientific and Technical Information of China (English)

    张建平; 武文丽; 朱文清

    2011-01-01

    In order to make statistic analysis on constant-stress and step-stress accelerated life test data for the infrared LED, the Weibull function was applied to describe its life distribution, and the maximum likelihood estimation (MLE) and its iterative flow chart were used to calculate the shape parameters and scale parameters. Furthermore, the accelerated life equation was determined by the least square method, the Kolmogorov-Smirnov test was performed to verify whether the life of the infrared LED meets the Weibull distribution or not,and self-developed software was employed to predict the average life and the midian life. The numerical results verified that the infrared LED life submits to the Weibull distribution, and the accelerated life equation meets completely the inverse power law. The estimated life information of the infrared LED can provide some significant guideline to its manufacturers and customers.%为了对红外发光二极管(LED)恒定及步进应力加速寿命试验的数据进行统计分析,应用weibull分布函数描述了其寿命分布,利用极大似然法(MLE)及其迭代流程图估计出形状参数和尺度参数,通过最小二乘法确定了红外LED加速寿命方程,对红外LED寿命是否符合威布尔分布进行了Kolmogorov-Smirnov检验,并利用自行开发的寿命预测软件计算出平均寿命和中位寿命.数值结果表明,红外LED的寿命服从we.bull分布,加速寿命方程符合逆幂定律,所估计出的红外LED的寿命对生产厂商和用户有很强的指导意义.

  14. Life prediction of 808nm high power semiconductor laser by accelerated life test of constant current stress

    Science.gov (United States)

    Yao, Nan; Li, Wei; Zhao, Yihao; Zhong, Li; Liu, Suping; Ma, Xiaoyu

    2015-10-01

    High power semiconductor laser is widely used because of its high transformation efficiency, good working stability, compact volume and simple driving requirements. Laser's lifetime is very long, but tests at high levels of stress can speed up the failure process and shorten the times to failure significantly. So accelerated life test is used here for forecasting the lifetime of 808nm CW GaAs/AlGaAs high power semiconductor laser that has an output power of 1W under 1.04A. Accelerated life test of constant current stress based on the Inverse Power Law Relationship was designed. Tests were conducted under 1.3A, 1.6A and 1.9A at room temperature. It is the first time that this method is used in the domestic research of laser's lifetime prediction. Applying Weibull Distribution to describe the lifetime distribution and analyzing the data of times to failure, characteristics lifetime's functional relationship model with current is achieved. Then the characteristics lifetime under normal current is extrapolated, which is 9473h. Besides, to confirm the validity of the functional relationship model, we conduct an additional accelerated life test under 1.75A. Based on this experimental data we calculated the characteristics lifetime corresponding to 1.75A that is 171h, while the extrapolated characteristics lifetime from the former functional relationship model is 162h. The two results shows 5% deviation that is very low and acceptable, which indicates that the test design is reasonable and authentic.

  15. Multi-Axial Damage Index and Accumulation Model for Predicting Fatigue Life of CMC Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The fatigue life of CMCs must be well characterized for the safe and reliable use of these materials as integrated TPS components. Existing fatigue life prediction...

  16. International Space Station Bacteria Filter Element Post-Flight Testing and Service Life Prediction

    Science.gov (United States)

    Perry, J. L.; von Jouanne, R. G.; Turner, E. H.

    2003-01-01

    The International Space Station uses high efficiency particulate air (HEPA) filters to remove particulate matter from the cabin atmosphere. Known as Bacteria Filter Elements (BFEs), there are 13 elements deployed on board the ISS's U.S. Segment. The pre-flight service life prediction of 1 year for the BFEs is based upon performance engineering analysis of data collected during developmental testing that used a synthetic dust challenge. While this challenge is considered reasonable and conservative from a design perspective, an understanding of the actual filter loading is required to best manage the critical ISS Program resources. Thus testing was conducted on BFEs returned from the ISS to refine the service life prediction. Results from this testing and implications to ISS resource management are discussed. Recommendations for realizing significant savings to the ISS Program are presented.

  17. Bi-variable damage model for fatigue life prediction of metal components

    Institute of Scientific and Technical Information of China (English)

    Miao Zhang; Qing-Chun Meng; Xing Zhang; Wei-Ping Hu

    2011-01-01

    Based on the theory of continuum damage mechanics, a bi-variable damage mechanics model is developed, which, according to thermodynamics, is accessible to derivation of damage driving force, damage evolution equation and damage evolution criteria. Furthermore, damage evolution equations of time rate are established by the generalized Drucker's postulate. The damage evolution equation of cycle rate is obtained by integrating the time damage evolution equations, and the fatigue life prediction method for smooth specimens under repeated loading with constant strain amplitude is constructed. Likewise, for notched specimens under the repeated loading with constant strain amplitude, the fatigue life prediction method is obtained on the ground of the theory of conservative integral in damage mechanics. Thus, the material parameters in the damage evolution equation can be obtained by reference to the fatigue test results of standard specimens with stress concentration factor equal to 1, 2 and 3.

  18. Basic traits predict the prevalence of personality disorder across the life span: the example of psychopathy.

    Science.gov (United States)

    Vachon, David D; Lynam, Donald R; Widiger, Thomas A; Miller, Joshua D; McCrae, Robert R; Costa, Paul T

    2013-05-01

    Personality disorders (PDs) may be better understood in terms of dimensions of general personality functioning rather than as discrete categorical conditions. Personality-trait descriptions of PDs are robust across methods and settings, and PD assessments based on trait measures show good construct validity. The study reported here extends research showing that basic traits (e.g., impulsiveness, warmth, straightforwardness, modesty, and deliberation) can re-create the epidemiological characteristics associated with PDs. Specifically, we used normative changes in absolute trait levels to simulate age-related differences in the prevalence of psychopathy in a forensic setting. Results demonstrated that trait information predicts the rate of decline for psychopathy over the life span; discriminates the decline of psychopathy from that of a similar disorder, antisocial PD; and accurately predicts the differential decline of subfactors of psychopathy. These findings suggest that basic traits provide a parsimonious account of PD prevalence across the life span.

  19. Basic traits predict the prevalence of personality disorder across the life span: the example of psychopathy.

    Science.gov (United States)

    Vachon, David D; Lynam, Donald R; Widiger, Thomas A; Miller, Joshua D; McCrae, Robert R; Costa, Paul T

    2013-05-01

    Personality disorders (PDs) may be better understood in terms of dimensions of general personality functioning rather than as discrete categorical conditions. Personality-trait descriptions of PDs are robust across methods and settings, and PD assessments based on trait measures show good construct validity. The study reported here extends research showing that basic traits (e.g., impulsiveness, warmth, straightforwardness, modesty, and deliberation) can re-create the epidemiological characteristics associated with PDs. Specifically, we used normative changes in absolute trait levels to simulate age-related differences in the prevalence of psychopathy in a forensic setting. Results demonstrated that trait information predicts the rate of decline for psychopathy over the life span; discriminates the decline of psychopathy from that of a similar disorder, antisocial PD; and accurately predicts the differential decline of subfactors of psychopathy. These findings suggest that basic traits provide a parsimonious account of PD prevalence across the life span. PMID:23528790

  20. Predicting the creep life and failure mode of low-alloy steel weldments

    Energy Technology Data Exchange (ETDEWEB)

    Brear, J.M.; Middleton, C.J.; Aplin, P.F. [ERA Technology Ltd., Leatherhead (United Kingdom)

    1998-12-31

    This presentation reviews and consolidates experience gained through a number of research projects and practical plant assessments in predicting both the life and the likely failure mode and location in low alloy steel weldments. The approach adopted begins with the recognition that the relative strength difference between the microstructural regions is a key factor controlling both life and failure location. Practical methods based on hardness measurement and adaptable to differing weld geometries are presented and evidence for correlations between hardness ratio, damage accumulation and strain development is discussed. Predictor diagrams relating weld life and failure location to the service conditions and the hardness of the individual microstructural constituents are suggested and comments are given on the implications for identifying the circumstances in which Type IV cracking is to be expected. (orig.) 6 refs.

  1. Deconstructing environmental predictability: seasonality, environmental colour and the biogeography of marine life histories.

    Science.gov (United States)

    Marshall, Dustin J; Burgess, Scott C

    2015-02-01

    Environmental predictability is predicted to shape the evolution of life histories. Two key types of environmental predictability, seasonality and environmental colour, may influence life-history evolution independently but formal considerations of both and how they relate to life history are exceedingly rare. Here, in a global biogeographical analysis of over 800 marine invertebrates, we explore the relationships between both forms of environmental predictability and three fundamental life-history traits: location of larval development (aplanktonic vs. planktonic), larval developmental mode (feeding vs. non-feeding) and offspring size. We found that both dispersal potential and offspring size related to environmental predictability, but the relationships depended on both the environmental factor as well as the type of predictability. Environments that were more seasonal in food availability had a higher prevalence of species with a planktonic larval stage. Future studies should consider both types of environmental predictability as each can strongly affect life-history evolution.

  2. Predicting Fatigue Life Based on the Behavior of Short Fatigue C rack%基于疲劳短裂纹行为的疲劳寿命估算方法

    Institute of Scientific and Technical Information of China (English)

    吕文阁

    2001-01-01

    The process of forming short fatigue crack was di vided into short fatigue crack initiation phase and short fatigue crack propagat ion phase. The theory of continuously distributed dislocations of crack was app l ied to analyze the early growth and the effect of microstructure of short fatigu e crack. The dislocations model of crack under cyclic stress was built based on the analysis of the equilibrium condition for dislocations when the applied stre ss was reduced. The reverse plastic displacement at the crack-tip was adjusted to discribe the growth of fatigue crack. The model was used in short fatigue cr a ck initiation with the physical background of the diceleration behavior of early growth of short fatigue crack. A fatigue limit diagram of hyperbola was derive d from the threshold stress condition of short fatiuge crack determined by the an alysis of interactions between early growth of short fatigue crack and grain bou ndary. The equation of short fatiuge crack growth rate was presented from the m o del related to the threshold stress condition of short fatigue crack. The ellip s oidal inhomogeneity method was applied to the study on elastic-plastic fractrue problem, and then the analytical expressions of crack-tip extension displaceme nt were found. The method in which crack-tip extension displacement range was u tilized to describe the rate of short fatigue crack propagation was presented. I t was found that the propagation rate of short fatigue cracks. Based on the beh a vior of initiation and propagation of short fatigue cracks, a method of predicti ong fatiuge life was proposed. The predicting result shows that this method was accurate enough.%在疲劳短裂纹形成和扩展行为研究基础上,提出了一种疲劳 寿命估算方法。计算结果表明,该方法具有满意的预测精度。

  3. Life prediction methodology for ceramic components of advanced heat engines. Phase 1: Volume 1, Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cuccio, J.C.; Brehm, P.; Fang, H.T. [Allied-Signal Aerospace Co., Phoenix, AZ (United States). Garrett Engine Div.] [and others

    1995-03-01

    Emphasis of this program is to develop and demonstrate ceramics life prediction methods, including fast fracture, stress rupture, creep, oxidation, and nondestructive evaluation. Significant advancements were made in these methods and their predictive capabilities successfully demonstrated.

  4. RandomForest4Life: a Random Forest for predicting ALS disease progression.

    Science.gov (United States)

    Hothorn, Torsten; Jung, Hans H

    2014-09-01

    We describe a method for predicting disease progression in amyotrophic lateral sclerosis (ALS) patients. The method was developed as a submission to the DREAM Phil Bowen ALS Prediction Prize4Life Challenge of summer 2012. Based on repeated patient examinations over a three- month period, we used a random forest algorithm to predict future disease progression. The procedure was set up and internally evaluated using data from 1197 ALS patients. External validation by an expert jury was based on undisclosed information of an additional 625 patients; all patient data were obtained from the PRO-ACT database. In terms of prediction accuracy, the approach described here ranked third best. Our interpretation of the prediction model confirmed previous reports suggesting that past disease progression is a strong predictor of future disease progression measured on the ALS functional rating scale (ALSFRS). We also found that larger variability in initial ALSFRS scores is linked to faster future disease progression. The results reported here furthermore suggested that approaches taking the multidimensionality of the ALSFRS into account promise some potential for improved ALS disease prediction. PMID:25141076

  5. An Integrated Approach to Fatigue Life Prediction of Whole System for Offshore Platforms

    Institute of Scientific and Technical Information of China (English)

    方华灿; 段梦兰; 许发彦; 吴永宁; 樊晓东

    2001-01-01

    The failure of one or even more components usually does not lead to the collapse of the whole structure. Most of theanalysis of fatigue is centered on only a single component which the researchers are interested in or much attentionshould be paid to. However, the collapse of a structure is the result of failure of a series of components in a specific orderor path. This paper proposes an integrated approach to fatigue life prediction of whole structural system for offshoreplatforms, mainly describing the basic principles and prediction method. A method is presented for determining the fail-ure path of the whole structure system and calculating the fatigue life in the determined failure path. The correspondingfinal collapse criteria for the whole structure system are discussed. A simple method of equivalent fatigue stress range cal-culation and a mathematical model of structural component fatigue life estimation in consideration of sea wave and seaice loads are provided. As an application of the proposed approach, a fixed production platform Bohai No. 8 is chosenfor the predication of fatigue life of the whole structure system by means of the software OSFAC developed based on thepresent methods.

  6. Application of cyclic damage accumulation life prediction model to high temperature components

    Science.gov (United States)

    Nelson, Richard S.

    1989-01-01

    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, but it can be applied to other materials as well. The method is designed to account for the effects on creep-fatigue life of complex loading such as thermomechanical fatigue, hold periods, waveshapes, mean stresses, multiaxiality, cumulative damage, coatings, and environmental attack. Several features of this model were developed to make it practical for application to actual component analysis, such as the ability to handle nonisothermal loading (including TMF), arbitrary cycle paths, and multiple damage modes. The CDA life prediction model was derived from extensive specimen tests conducted on cast nickel-base superalloy B1900 + Hf. These included both monotonic tests (tensile and creep) and strain-controlled fatigue experiments (uniaxial, biaxial, TMF, mixed creep-fatigue, and controlled mean stress). Additional specimen tests were conducted on wrought INCO 718 to verify the applicability of the final CDA model to other high-temperature alloys. The model will be available to potential users in the near future in the form of a FORTRAN-77 computer program.

  7. 基于美国ASME标准的重载货车车体焊缝疲劳寿命预测%Fatigue life prediction for weld line in heavy freight carbody based on ASME standard

    Institute of Scientific and Technical Information of China (English)

    谢素明; 周晓坤; 李向伟; 李晓峰

    2012-01-01

    为寻求在设计阶段能较准确地预测重载货车车体焊缝的疲劳寿命评估方法,基于各种标准提供的分析方法对转炉616装甲钢T型焊接接头进行疲劳评估,通过与试验的对比表明,美国ASME标准中的等效结构应力法更能准确预测焊缝的疲劳寿命。为提高某重载运煤敞车车体焊缝的疲劳寿命,建立了包括焊缝在内的敞车车体有限元模型,基于等效结构应力法和AAR标准中的载荷谱,预测了车体关键焊缝的疲劳寿命,其薄弱部位与车体实际发生疲劳裂纹部位基本吻合,依据焊缝的结构应力分布规律的特点,提出的枕梁改进结构可使车体关键焊缝疲劳寿命提高1.7倍。%Aiming at finding a more exact method to predict weld line fatigue life in heavy freight carbody during design phase, the fatigue life of armor steel 616 Tee joint is analyzed by various standards. Comparing analysis results and experimental results,the equivalent structural stress method offered by ASME standard is of high accuracy and obvious advantage. A finite element model of a heavy freight carbody including key weld lines is built, fatigue life prediction for these weld lines is performed by means of the equivalent structural stress method and load spectrum of AAR,and weld line of more shorter fatigue life is basically coincident with that in-service carbody. The improved structure of bolsters is to be put forward on the basis of structural stress analysis at weld lines, and fatigue life of the bolsters weld line is increased by 1.7 times.

  8. Probabilistic Remaining Useful Life Prediction of Composite Aircraft Components Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A Probabilistic Fatigue Damage Assessment Network (PFDAN) toolkit for Abaqus will be developed for probabilistic life management of a laminated composite structure...

  9. Creep-fatigue life prediction for engine hot section materials (isotropic)

    Science.gov (United States)

    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.

  10. Game-Based Life-Long Learning

    NARCIS (Netherlands)

    Kelle, Sebastian; Sigurðarson, Steinn; Westera, Wim; Specht, Marcus

    2010-01-01

    Kelle, S., Sigurðarson, S., Westera, W., & Specht, M. (2011). Game-Based Life-Long Learning. In G. D. Magoulas (Ed.), E-Infrastructures and Technologies for Lifelong Learning: Next Generation Environments (pp. 337-349). Hershey, PA: IGI Global.

  11. A novel health indicator for on-line lithium-ion batteries remaining useful life prediction

    Science.gov (United States)

    Zhou, Yapeng; Huang, Miaohua; Chen, Yupu; Tao, Ye

    2016-07-01

    Prediction of lithium-ion batteries remaining useful life (RUL) plays an important role in an intelligent battery management system. The capacity and internal resistance are often used as the batteries health indicator (HI) for quantifying degradation and predicting RUL. However, on-line measurement of capacity and internal resistance are hardly realizable due to the not fully charged and discharged condition and the extremely expensive cost, respectively. Therefore, there is a great need to find an optional way to deal with this plight. In this work, a novel HI is extracted from the operating parameters of lithium-ion batteries for degradation modeling and RUL prediction. Moreover, Box-Cox transformation is employed to improve HI performance. Then Pearson and Spearman correlation analyses are utilized to evaluate the similarity between real capacity and the estimated capacity derived from the HI. Next, both simple statistical regression technique and optimized relevance vector machine are employed to predict the RUL based on the presented HI. The correlation analyses and prediction results show the efficiency and effectiveness of the proposed HI for battery degradation modeling and RUL prediction.

  12. 基于 Gram-Schmidt 回归的军械器材储存期限测算方法%Shelf Life Prediction Modeling for Ordnance Equipment Based on Gram-Schmidt Regression

    Institute of Scientific and Technical Information of China (English)

    李志伟; 高崎; 刘慎洋; 杨志远

    2015-01-01

    In order to overcome the difficulty of selecting the suitable regression items especially the non-linear regression items and eliminating the influence of multicollinearity when conducting mass modeling tasks,an ordnance equipment shelf life calculation method using Gram-Schmidt regression is put forward. This method can select the critical modeling items in all the available items in turn,and the influence of multicollinearity can be eliminated by deducting the orthogonal components.Mass of shelf life prediction models can be developed in this method,and the process is very standardized and easy programming.Fi-nally,an example of predicting rubber type of ordnance equipment is taken to test and verify the method. Results show that the nonlinear terms of regression model selected by modeling process is consistent with Dakin equation,and the predicted values of natural rubber shelf life are coordinated with factory settings.%针对军械器材储存期限测算任务量大、时间紧迫,批量建模时与环境因素相关的回归项尤其是非线,项难以确定,因素间的多重共线,难以消除等问题,提出了一种基于 Gram-Schmidt 回归的军械器材储存期限测算方法。该方法可在众多备选非线,项中依次找到关键的影响因素,并利用消减投影分量的方法消除多重共线,的不良影响;利用该方法可批量构建储存期限测算模型,且测算流程规范、统一,易于编程实现。最后以橡胶类军械器材为例对该方法进行了验证,结果表明:批量建模选出的非线,项与 Dakin 寿命方程相符,测算的常温下天然橡胶的储存期限值与出厂值相符。

  13. Prediction of Fatigue Life of Gear Subjected to Varying Loads

    Directory of Open Access Journals (Sweden)

    D. Hanumanna

    1998-07-01

    Full Text Available Structural members and components of a vehicle during service are subjected to varying loads which are random in nature. For structural members subjected to loads of constant amplitude, it is possible to describe the load with explicit mathematical relationship, and thereby, the life span can be estimated. Whereas, for structural members subjected to varying loads with time, there is no satisfactory method to estimate their life span. This paper describes a method for the estimation of life span of a gear in the gear box of a fighting vehicle subjected to fluctuating loads. For this purpose, it is assumed that the load spectrum corresponds to Gaussian (normal distribution, and the life has been worked out by applying linear cumulative damage theory.

  14. Age at the onset of senescence in birds and mammals is predicted by early-life performance.

    Science.gov (United States)

    Péron, Guillaume; Gimenez, Olivier; Charmantier, Anne; Gaillard, Jean-Michel; Crochet, Pierre-André

    2010-09-22

    Life-history theory predicts that traits involved in maturity, reproduction and survival correlate along a fast-slow continuum of life histories. Evolutionary theories and empirical results indicate that senescence-related traits vary along this continuum, with slow species senescing later and at a slower pace than fast species. Because senescence patterns are typically difficult to estimate from studies in the wild, here we propose to predict the associated trait values in the frame of life-history theory. From a comparative analysis based on 81 free-ranging populations of 72 species of birds and mammals, we find that a nonlinear combination of fecundity, age at first reproduction and survival over the immature stage can account for ca two-thirds of the variance in the age at the onset of actuarial senescence. Our life-history model performs better than a model predicting the onset based on generation time, and it only includes life-history traits during early life as explanatory variables, i.e. parameters that are both theoretically expected to shape senescence and are measurable within relatively short studies. We discuss the good-fit of our life-history model to the available data in the light of current evolutionary theories of senescence. We further use it to evaluate whether studies that provided no evidence for senescence lasted long enough to include the onset of senescence.

  15. Method for estimating capacity and predicting remaining useful life of lithium-ion battery

    International Nuclear Information System (INIS)

    Highlights: • We develop an integrated method for the capacity estimation and RUL prediction. • A state projection scheme is derived for capacity estimation. • The Gauss–Hermite particle filter technique is used for the RUL prediction. • Results with 10 years’ continuous cycling data verify the effectiveness of the method. - Abstract: Reliability of lithium-ion (Li-ion) rechargeable batteries used in implantable medical devices has been recognized as of high importance from a broad range of stakeholders, including medical device manufacturers, regulatory agencies, physicians, and patients. To ensure Li-ion batteries in these devices operate reliably, it is important to be able to assess the capacity of Li-ion battery and predict the remaining useful life (RUL) throughout the whole life-time. This paper presents an integrated method for the capacity estimation and RUL prediction of Li-ion battery used in implantable medical devices. A state projection scheme from the author’s previous study is used for the capacity estimation. Then, based on the capacity estimates, the Gauss–Hermite particle filter technique is used to project the capacity fade to the end-of-service (EOS) value (or the failure limit) for the RUL prediction. Results of 10 years’ continuous cycling test on Li-ion prismatic cells in the lab suggest that the proposed method achieves good accuracy in the capacity estimation and captures the uncertainty in the RUL prediction. Post-explant weekly cycling data obtained from field cells with 4–7 implant years further verify the effectiveness of the proposed method in the capacity estimation

  16. Trust-based collective view prediction

    CERN Document Server

    Luo, Tiejian; Xu, Guandong; Zhou, Jia

    2013-01-01

    Collective view prediction is to judge the opinions of an active web user based on unknown elements by referring to the collective mind of the whole community. Content-based recommendation and collaborative filtering are two mainstream collective view prediction techniques. They generate predictions by analyzing the text features of the target object or the similarity of users' past behaviors. Still, these techniques are vulnerable to the artificially-injected noise data, because they are not able to judge the reliability and credibility of the information sources. Trust-based Collective View

  17. Creep fatigue life prediction for engine hot section materials (isotropic): Third year progress review

    Science.gov (United States)

    Nelson, Richard S.; Schoendorf, John F.

    1985-01-01

    This program is designed to investigate fundamental damage processes, identify modeling strategies, and develop practical models which can be used to guide the early design and development of new engines and to increase the durability of existing engines. A review is given of the base program, completed in 1984, which included the comparison and evaluation of several popular high-temperature life prediction approaches as applied to continuously cycled isothermal specimen tests. The option program, of which one year is completed, is designed to develop models which can account for complex cycles and loadings, such as thermomechanical cycling, cumulative damage, multiaxial stress/strain rates, and environmental effects.

  18. Towards Practical Carbonation Prediction and Modelling for Service Life Design of Reinforced Concrete Structures

    Science.gov (United States)

    Ekolu, O. S.

    2015-11-01

    Amongst the scientific community, the interest in durability of concrete structures has been high for quite a long time of over 40 years. Of the various causes of degradation of concrete structures, corrosion is the most widespread durability problem and carbonation is one of the two causes of steel reinforcement corrosion. While much scientific understanding has been gained from the numerous carbonation studies undertaken over the past years, it is still presently not possible to accurately predict carbonation and apply it in design of structures. This underscores the complex nature of the mechanisms as influenced by several interactive factors. Based on critical literature and some experience of the author, it is found that there still exist major challenges in establishing a mathematical constitutive relation for realistic carbonation prediction. While most current models employ permeability /diffusion as the main model property, analysis shows that the most practical material property would be compressive strength, which has a low coefficient of variation of 20% compared to 30 to 50% for permeability. This important characteristic of compressive strength, combined with its merit of simplicity and data availability at all stages of a structure's life, promote its potential use in modelling over permeability. By using compressive strength in carbonation prediction, the need for accelerated testing and permeability measurement can be avoided. This paper attempts to examine the issues associated with carbonation prediction, which could underlie the current lack of a sound established prediction method. Suggestions are then made for possible employment of different or alternative approaches.

  19. Predicting the evolution of social networks with life cycle events

    OpenAIRE

    Sharmeen, F Fariya; Arentze, TA Theo; Timmermans, HJP Harry

    2015-01-01

    This paper presents a model of social network evolution, to predict and simulate changes in social networks induced by lifecycle events. We argue that social networks change with lifecycle events, and we extend a model of friendship selection to incorporate these dynamics of personal social networks. The model uses theories of homophily and reciprocity and is formulated in a random utility maximization framework to predict the formation of social ties between individuals in the population. It...

  20. Knowledge-Based Systems in Biomedicine and Computational Life Science

    CERN Document Server

    Jain, Lakhmi

    2013-01-01

    This book presents a sample of research on knowledge-based systems in biomedicine and computational life science. The contributions include: ·         personalized stress diagnosis system ·         image analysis system for breast cancer diagnosis ·         analysis of neuronal cell images ·         structure prediction of protein ·         relationship between two mental disorders ·         detection of cardiac abnormalities ·         holistic medicine based treatment ·         analysis of life-science data  

  1. Fuzzy Activity Based Life Cycle Costing For Repairable Equipment

    Directory of Open Access Journals (Sweden)

    Mulubrhan Freselam

    2016-01-01

    Full Text Available Life-cycle cost (LCC is the much known method used for decision making that considers all costs in the life of a system or equipment. Predicting LCCs is fraught with potential errors, owing to the uncertainty in future events, future costs, interest rates, and even hidden costs. These uncertainties have a direct impact on the decision making. Activity based LCC is used to identify the activities and cost drivers in acquisition, operation and maintenance phase. This activity based LCC is integrated with fuzzy set theory and interval mathematics to model these uncertainties. Day–Stout–Warren (DSW algorithm and the vertex method are then used to evaluate competing alternatives. A case of two pumps (Pump A and Pump B are taken and their LCC is analysed using the developed model. The equivalent annual cost of Pump B is greater than Pump A, which leads the decision maker to choose Pump A over Pump B.

  2. Predicting professional quality of life among professional and volunteer caregivers.

    Science.gov (United States)

    Avieli, Hila; Ben-David, Sarah; Levy, Inna

    2016-01-01

    This study is one of the few that has compared volunteers' professional quality of life (PQL), which includes secondary traumatic stress (STS), burnout, and compassion satisfaction (CS), to those of professional caregivers. In addition, the research compared the ethical behavior of volunteers with that of professional therapists and examined the connection between years of experience, ethical behavior, and PQL. One hundred eighty-three volunteers and professional caregivers filled out a sociodemographic questionnaire, an Ethical Behavior Questionnaire and the Professional Quality of Life (ProQOL) questionnaire. The results indicated that professional caregivers report lower levels of STS and burnout, and higher levels of CS and ethical behavior compared with volunteer caregivers. Moreover, the findings suggest that ethical behavior correlates with STS, burnout, and CS. Ethical behavior has a protective value for mental health caregivers. The discussion emphasizes the value of a professional code of ethics and ethical training for professional and volunteering caregivers. PMID:26121172

  3. Speech Intelligibility Prediction Based on Mutual Information

    DEFF Research Database (Denmark)

    Jensen, Jesper; Taal, Cees H.

    2014-01-01

    This paper deals with the problem of predicting the average intelligibility of noisy and potentially processed speech signals, as observed by a group of normal hearing listeners. We propose a model which performs this prediction based on the hypothesis that intelligibility is monotonically related...... to the mutual information between critical-band amplitude envelopes of the clean signal and the corresponding noisy/processed signal. The resulting intelligibility predictor turns out to be a simple function of the mean-square error (mse) that arises when estimating a clean critical-band amplitude using...... a minimum mean-square error (mmse) estimator based on the noisy/processed amplitude. The proposed model predicts that speech intelligibility cannot be improved by any processing of noisy critical-band amplitudes. Furthermore, the proposed intelligibility predictor performs well ( ρ > 0.95) in predicting...

  4. Calorimeter prediction based on multiple exponentials

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.K. E-mail: mks@lanl.gov; Bracken, D.S

    2002-05-21

    Calorimetry allows very precise measurements of nuclear material to be carried out, but it also requires relatively long measurement times to do so. The ability to accurately predict the equilibrium response of a calorimeter would significantly reduce the amount of time required for calorimetric assays. An algorithm has been developed that is effective at predicting the equilibrium response. This multi-exponential prediction algorithm is based on an iterative technique using commercial fitting routines that fit a constant plus a variable number of exponential terms to calorimeter data. Details of the implementation and the results of trials on a large number of calorimeter data sets will be presented.

  5. Calorimeter prediction based on multiple exponentials

    International Nuclear Information System (INIS)

    Calorimetry allows very precise measurements of nuclear material to be carried out, but it also requires relatively long measurement times to do so. The ability to accurately predict the equilibrium response of a calorimeter would significantly reduce the amount of time required for calorimetric assays. An algorithm has been developed that is effective at predicting the equilibrium response. This multi-exponential prediction algorithm is based on an iterative technique using commercial fitting routines that fit a constant plus a variable number of exponential terms to calorimeter data. Details of the implementation and the results of trials on a large number of calorimeter data sets will be presented

  6. Calorimeter prediction based on multiple exponentials

    CERN Document Server

    Smith, M K

    2002-01-01

    Calorimetry allows very precise measurements of nuclear material to be carried out, but it also requires relatively long measurement times to do so. The ability to accurately predict the equilibrium response of a calorimeter would significantly reduce the amount of time required for calorimetric assays. An algorithm has been developed that is effective at predicting the equilibrium response. This multi-exponential prediction algorithm is based on an iterative technique using commercial fitting routines that fit a constant plus a variable number of exponential terms to calorimeter data. Details of the implementation and the results of trials on a large number of calorimeter data sets will be presented.

  7. Extreme Environment Damage Index and Accumulation Model for CMC Laminate Fatigue Life Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Materials Research & Design (MR&D) is proposing in the SBIR Phase II an effort to develop a tool for predicting the fatigue life of C/SiC composite...

  8. Study on effect of mean stress on fatigue life prediction of thin film structure

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Myung Soo [Ahtti Co., Seongnam (Korea, Republic of); Park, Jun Hyu [Tongmyong University, Busan (Korea, Republic of); Kim, Jung Yup [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2016-04-15

    This paper describes the effect of mean stress on fatigue life prediction of structure made with thin film. It is well known that the mean stress influences fatigue life prediction of mechanical structure. We investigated a reasonable method for considering mean stress when fatigue strength assessment of micro structure of thin film should be performed. Fatigue tests of smooth specimen of beryllium-copper (BeCu) thin film were performed in ambient air at R = 0.1 with 5 Hz. A micro probe was designed and made with BeCu thin film by the precision press process. Fatigue tests of micro structure were performed with 5 Hz frequency, in ambient air to verify the fatigue life predicted by computer simulation through FE analysis. The fatigue life predicted by the Sa -N curve modified by Goodman method with principal stress through FE analysis shows a more reasonable result than other methods.

  9. Time-Delay Artificial Neural Network Computing Models for Predicting Shelf Life of Processed Cheese

    OpenAIRE

    Sumit Goyal; Gyanendra Kumar Goyal

    2012-01-01

    This paper presents the capability of Time–delay artificial neural network models for predicting shelf life of processed cheese. Datasets were divided into two subsets (30 for training and 6 for validation). Models with single and multi layers were developed and compared with each other. Mean Square Error, Root Mean Square Error, Coefficient of Determination and Nash -
    Sutcliffo Coefficient were used as performance evaluators, Time- delay model predicted the shelf life of...

  10. Creep fatigue life prediction for engine hot section materials (isotropic): Two year update

    Science.gov (United States)

    Moreno, V.

    1984-01-01

    Requirements for increased durability of gas turbine hot section components have placed a greater degree of importance on accurate structural analysis and life prediction. Various life prediction approaches for high temperature applications were investigated. Basic models were selected and developed for simple-cycle, isothermal loading conditions. Models will be developed which address thermomechanical cycling, multiaxial conditions, cumulative loading, environmental effects, and cyclic mean stress. Verification tests of models will be conducted on an alternate material and coating system.

  11. A Hybrid Prognostic Approach for Remaining Useful Life Prediction of Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Wen-An Yang

    2016-01-01

    Full Text Available Lithium-ion battery is a core component of many systems such as satellite, spacecraft, and electric vehicles and its failure can lead to reduced capability, downtime, and even catastrophic breakdowns. Remaining useful life (RUL prediction of lithium-ion batteries before the future failure event is extremely crucial for proactive maintenance/safety actions. This study proposes a hybrid prognostic approach that can predict the RUL of degraded lithium-ion batteries using physical laws and data-driven modeling simultaneously. In this hybrid prognostic approach, the relevant vectors obtained with the selective kernel ensemble-based relevance vector machine (RVM learning algorithm are fitted to the physical degradation model, which is then extrapolated to failure threshold for estimating the RUL of the lithium-ion battery of interest. The experimental results indicated that the proposed hybrid prognostic approach can accurately predict the RUL of degraded lithium-ion batteries. Empirical comparisons show that the proposed hybrid prognostic approach using the selective kernel ensemble-based RVM learning algorithm performs better than the hybrid prognostic approaches using the popular learning algorithms of feedforward artificial neural networks (ANNs like the conventional backpropagation (BP algorithm and support vector machines (SVMs. In addition, an investigation is also conducted to identify the effects of RVM learning algorithm on the proposed hybrid prognostic approach.

  12. Energy based prediction models for building acoustics

    DEFF Research Database (Denmark)

    Brunskog, Jonas

    2012-01-01

    In order to reach robust and simplified yet accurate prediction models, energy based principle are commonly used in many fields of acoustics, especially in building acoustics. This includes simple energy flow models, the framework of statistical energy analysis (SEA) as well as more elaborated...... principles as, e.g., wave intensity analysis (WIA). The European standards for building acoustic predictions, the EN 12354 series, are based on energy flow and SEA principles. In the present paper, different energy based prediction models are discussed and critically reviewed. Special attention is placed...... on underlying basic assumptions, such as diffuse fields, high modal overlap, resonant field being dominant, etc., and the consequences of these in terms of limitations in the theory and in the practical use of the models....

  13. Fundamental understanding and life prediction of stress corrosion cracking in BWRs and energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Andresen, P.L.; Ford, F.P. [General Electric, Schenectady, NY (United States). Corporate Research and Development Center

    1998-03-01

    The objective of this paper is to present an approach for design and lifetime evaluation of environmental cracking based on experimental and fundamental modeling of the underlying processes operative in crack advance. In detailed this approach and its development and quantification for energy (hot water) systems, the requirements for a life prediction methodology will be highlighted and the shortcomings of the existing design and lifetime evaluation codes reviewed. Examples are identified of its use in a variety of cracking systems, such as stainless steels, low alloy steels, nickel base alloys, and irradiation assisted stress corrosion cracking in boiling water reactor (BWR) water, as well as preliminary use for low alloy steel and Alloy 600 in pressurized water reactors (PWRs) and turbine steels in steam turbines. Identification of the common aspects with environmental cracking in other hot water systems provides a secure basis for its extension to related energy systems. 166 refs., 49 figs.

  14. Academic Life Satisfaction Scale (ALSS) and Its Effectiveness in Predicting Academic Success

    Science.gov (United States)

    Kumar, P.K. Sudheesh; P., Dileep

    2006-01-01

    This study is undertaken to examine the effectiveness of a newly constructed psychometric instrument to assess Academic Life Satisfaction along with the components of Emotional Intelligence. The Academic Life Satisfaction Scale is used to predict the scholastic achievement as an index of Academic success. The investigators found that Academic Life…

  15. Predicting Trajectories of Offending over the Life Course: Findings from a Dutch Conviction Cohort

    Science.gov (United States)

    Bersani, Bianca E.; Nieuwbeerta, Paul; Laub, John H.

    2009-01-01

    Distinguishing trajectories of criminal offending over the life course, especially the prediction of high-rate offenders, has received considerable attention over the past two decades. Motivated by a recent study by Sampson and Laub (2003), this study uses longitudinal data on conviction histories from the Dutch Criminal Career and Life-Course…

  16. Structural health monitoring for fatigue life prediction of orthotropic brdige decks

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Lotfollah Pahlavan, P.; Paulissen, J.H.; Hakkesteegt, H.C.; Jansen, T.H.

    2013-01-01

    Infrastructure asset owners are more and more confronted with structures reaching the end of their structural life. Structural Health Monitoring (SHM) systems should provide up-to-date information about the actual condition, as well predict the structural life and required maintenance of the assets

  17. A review on fatigue life prediction methods for anti-vibration rubber materials

    Directory of Open Access Journals (Sweden)

    Xiaoli WANG

    2016-08-01

    Full Text Available Anti-vibration rubber, because of its superior elasticity, plasticity, waterproof and trapping characteristics, is widely used in the automotive industry, national defense, construction and other fields. The theory and technology of predicting fatigue life is of great significance to improve the durability design and manufacturing of anti-vibration rubber products. According to the characteristics of the anti-vibration rubber products in service, the technical difficulties for analyzing fatigue properties of anti-vibration rubber materials are pointed out. The research progress of the fatigue properties of rubber materials is reviewed from three angles including methods of fatigue crack initiation, fatigue crack propagation and fatigue damage accumulation. It is put forward that some nonlinear characteristics of rubber under fatigue loading, including the Mullins effect, permanent deformation and cyclic stress softening, should be considered in the further study of rubber materials. Meanwhile, it is indicated that the fatigue damage accumulation method based on continuum damage mechanics might be more appropriate to solve fatigue damage and life prediction problems for complex rubber materials and structures under fatigue loading.

  18. Testing and Life Prediction for Composite Rotor Hub Flexbeams

    Science.gov (United States)

    Murri, Gretchen B.

    2004-01-01

    A summary of several studies of delamination in tapered composite laminates with internal ply-drops is presented. Initial studies used 2D FE models to calculate interlaminar stresses at the ply-ending locations in linear tapered laminates under tension loading. Strain energy release rates for delamination in these laminates indicated that delamination would likely start at the juncture of the tapered and thin regions and grow unstably in both directions. Tests of glass/epoxy and graphite/epoxy linear tapered laminates under axial tension delaminated as predicted. Nonlinear tapered specimens were cut from a full-size helicopter rotor hub and were tested under combined constant axial tension and cyclic transverse bending loading to simulate the loading experienced by a rotorhub flexbeam in flight. For all the tested specimens, delamination began at the tip of the outermost dropped ply group and grew first toward the tapered region. A 2D FE model was created that duplicated the test flexbeam layup, geometry, and loading. Surface strains calculated by the model agreed very closely with the measured surface strains in the specimens. The delamination patterns observed in the tests were simulated in the model by releasing pairs of MPCs along those interfaces. Strain energy release rates associated with the delamination growth were calculated for several configurations and using two different FE analysis codes. Calculations from the codes agreed very closely. The strain energy release rate results were used with material characterization data to predict fatigue delamination onset lives for nonlinear tapered flexbeams with two different ply-dropping schemes. The predicted curves agreed well with the test data for each case studied.

  19. A Fatigue Life Prediction Model of Welded Joints under Combined Cyclic Loading

    Science.gov (United States)

    Goes, Keurrie C.; Camarao, Arnaldo F.; Pereira, Marcos Venicius S.; Ferreira Batalha, Gilmar

    2011-01-01

    A practical and robust methodology is developed to evaluate the fatigue life in seam welded joints when subjected to combined cyclic loading. The fatigue analysis was conducted in virtual environment. The FE stress results from each loading were imported to fatigue code FE-Fatigue and combined to perform the fatigue life prediction using the S x N (stress x life) method. The measurement or modelling of the residual stresses resulting from the welded process is not part of this work. However, the thermal and metallurgical effects, such as distortions and residual stresses, were considered indirectly through fatigue curves corrections in the samples investigated. A tube-plate specimen was submitted to combined cyclic loading (bending and torsion) with constant amplitude. The virtual durability analysis result was calibrated based on these laboratory tests and design codes such as BS7608 and Eurocode 3. The feasibility and application of the proposed numerical-experimental methodology and contributions for the technical development are discussed. Major challenges associated with this modelling and improvement proposals are finally presented.

  20. Gas Generation in Radioactive Wastes - MAGGAS Predictive Life Cycle Model

    International Nuclear Information System (INIS)

    Gases may form from radioactive waste in quantities posing different potential hazards throughout the waste package life cycle. The latter includes surface storage, transport, placing in an operating repository, storage in the repository prior to backfill, closure and the post-closure stage. Potentially hazardous situations involving gas include fire, flood, dropped packages, blocked package vents and disruption to a sealed repository. The MAGGAS (Magnox Gas generation) model was developed to assess gas formation for safety assessments during all stages of the waste package life cycle. This is a requirement of the U.K. regulatory authorities and Nirex and progress in this context is discussed. The processes represented in the model include: Corrosion, microbial degradation, radiolysis, solid-state diffusion, chemico-physical degradation and pressurisation. The calculation was split into three time periods. First the 'aerobic phase' is used to model the periods of surface storage, transport and repository operations including storage in the repository prior to backfill. The second and third periods were designated 'anaerobic phase 1' and 'anaerobic phase 2' and used to model the waste packages in the post-closure phase of the repository. The various significant gas production processes are modeled in each phase. MAGGAS (currently Version 8) is mounted on an Excel spreadsheet for ease of use and speed, has 22 worksheets and is operated routinely for assessing waste packages (e.g. for ventilation of stores and pressurisation of containers). Ten operational and decommissioning generic nuclear power station waste streams were defined as initial inputs, which included ion exchange materials, sludges and concentrates, fuel element debris, graphite debris, activated components, contaminated items, desiccants and catalysts. (authors)

  1. Time Series Prediction Based on Chaotic Attractor

    Institute of Scientific and Technical Information of China (English)

    LIKe-Ping; CHENTian-Lun; GAOZi-You

    2003-01-01

    A new prediction technique is proposed for chaotic time series. The usefulness of the technique is that it can kick off some false neighbor points which are not suitable for the local estimation of the dynamics systems. A time-delayed embedding is used to reconstruct the underlying attractor, and the prediction model is based on the time evolution of the topological neighboring in the phase space. We use a feedforward neural network to approximate the local dominant Lyapunov exponent, and choose the spatial neighbors by the Lyapunov exponent. The model is tested for the Mackey-Glass equation and the convection amplitude of lorenz systems. The results indicate that this prediction technique can improve the prediction of chaotic time series.

  2. 青少年非理性信念与应激对抑郁症状预测研究%Prediction of depression symptoms based on irrational belief and life stress in adolescents

    Institute of Scientific and Technical Information of China (English)

    陈学彬; 梁妍; 刘琦; 王文; 杨静

    2012-01-01

    Objective: To explore the impact of irrational belief and life stress on depressive symptoms in adolescents. Method;649 middle school students were sampled and investigated using the Beck depression inventory-II (BDI-II) ,the middle-school students'irrational belief scale (MIBS) and stressor scale for middle school students (SSMSS). Life stress and depressive symptoms of each subject were evaluated every two months and the evaluation lasted for a year. The data were analyzed with Hierarchical Linear Model. Results: Irrational belief has significant positive correlation with depressive symptoms (r =0. 53,P0.05] . Conclusion:The irrational belief can predict depressive symptoms of the adolescents according to the life stress.%目的:探讨青少年非理性信念与生活应激对抑郁症状的影响. 方法:采用Beck抑郁自评问卷(BDI-Ⅱ)、中学生非理性信念量表(MIBS)和中学生心理应激源量表(SSMSS)等自评量表对649名中学生进行问卷调查,每2个月1次对生活应激和抑郁症状进行追踪测评,追踪为期1年完成6次测评,采用多层线性模型进行数据分析. 结果:非理性信念与抑郁症状(r=0.53,P<0.001)、生活应激水平(r=0.31,P<0.001)之间存在显著的正相关;多层线性模型分析表明,非理性信念[β=1.76,t(1629) =7.811,P<0.001]和生活应激水平[β=0.13,t(12635) =7.056,P<0.001]对青少年抑郁症状预测的主效应均显著,非理性信念与生活应激水平共同预测青少年抑郁症状的交互作用显著[β=0.04,t(12635)=4.173,P<0.001];随着生活应激水平增加,高非理性信念水平[β=0.07,t(2635)=7.484,P<0.001]青少年的抑郁症状水平比低非理性信念组[β=0.01,t(2635)=0.871,P>0.05]明显增加.结论:非理性信念在生活应激中能够预测青少年抑郁症状的发生和变化.

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

    Science.gov (United States)

    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.

  4. Predicting Learned Helplessness Based on Personality

    Science.gov (United States)

    Maadikhah, Elham; Erfani, Nasrollah

    2014-01-01

    Learned helplessness as a negative motivational state can latently underlie repeated failures and create negative feelings toward the education as well as depression in students and other members of a society. The purpose of this paper is to predict learned helplessness based on students' personality traits. The research is a predictive…

  5. SOFT COMPUTING SINGLE HIDDEN LAYER MODELS FOR SHELF LIFE PREDICTION OF BURFI

    Directory of Open Access Journals (Sweden)

    Sumit Goyal

    2012-05-01

    Full Text Available Burfi is an extremely popular sweetmeat, which is prepared by desiccating the standardized water buffalo milk. Soft computing feedforward single layer models were developed for predicting the shelf life of burfi stored at 30g.C. The data of the product relating to moisture, titratable acidity, free fatty acids, tyrosine, and peroxide value were used as input variables, and the overall acceptability score as output variable. The results showed excellent agreement between the experimental and the predicted data, suggesting that the developed soft computing model can alternatively be used for predicting the shelf life of burfi.

  6. Prediction of multiaxial fatigue life for notched specimens of titanium alloy TC4

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z. R.; Li, Z. X. [Southeast University, Nanjing (China); Hu, X. T.; Song, Y. D. [Nanjing University, Nanjing (China)

    2016-05-15

    Both the proportional and nonproportional multiaxial fatigue tests were conducted on two kinds of notched specimens of titanium alloy TC4. The multiaxial fatigue critical area of notched specimen is considered as the location experiencing the maximum damage. It is unsatisfactory to predict the multiaxial fatigue life with the local stress and strain in the fatigue critical area. The critical distance concepts are employed in the multiaxial life prediction method for notched specimens. The proposed method was checked by the test data of TC4 notched specimens. The prediction results are almost within a factor of three scatter band of the test results.

  7. LINEAR LAYER AND GENERALIZED REGRESSION COMPUTATIONAL INTELLIGENCE MODELS FOR PREDICTING SHELF LIFE OF PROCESSED CHEESE

    Directory of Open Access Journals (Sweden)

    S. Goyal

    2012-03-01

    Full Text Available This paper highlights the significance of computational intelligence models for predicting shelf life of processed cheese stored at 7-8 g.C. Linear Layer and Generalized Regression models were developed with input parameters: Soluble nitrogen, pH, Standard plate count, Yeast & mould count, Spores, and sensory score as output parameter. Mean Square Error, Root Mean Square Error, Coefficient of Determination and Nash - Sutcliffo Coefficient were used in order to compare the prediction ability of the models. The study revealed that Generalized Regression computational intelligence models are quite effective in predicting the shelf life of processed cheese stored at 7-8 g.C.

  8. TMC Behavior Modeling and Life Prediction Under Multiaxial Stresses

    Science.gov (United States)

    Merrick, H. F.; Aksoy, S. Z.; Costen, M.; Ahmad, J.

    1998-01-01

    The goal of this program was to manufacture and burst test small diameter SCS-6/Ti-6Al-4V composite rings for use in the design of an advanced titanium matrix composite (TMC) impeller. The Textron Specialty Metals grooved foil-fiber process was successfully used to make high quality TMC rings. A novel spin test arbor with "soft touch" fingers to retain the TMC ring was designed and manufactured. The design of the arbor took into account its use for cyclic experiments as well as ring burst tests. Spin testing of the instrumented ring was performed at ambient, 149C (300F), and 316C (600F) temperatures. Assembly vibration was encountered during spin testing but this was overcome through simple modification of the arbor. A spin-to-burst test was successfully completed at 316C (600F). The rotational speed of the TMC ring at burst was close to that predicted. In addition to the spin test program, a number of SCS-6/Ti-6Al-4V test panels were made. Neat Ti-6Al-4V panels also were made.

  9. Planner-Based Control of Advanced Life Support Systems

    Science.gov (United States)

    Muscettola, Nicola; Kortenkamp, David; Fry, Chuck; Bell, Scott

    2005-01-01

    The paper describes an approach to the integration of qualitative and quantitative modeling techniques for advanced life support (ALS) systems. Developing reliable control strategies that scale up to fully integrated life support systems requires augmenting quantitative models and control algorithms with the abstractions provided by qualitative, symbolic models and their associated high-level control strategies. This will allow for effective management of the combinatorics due to the integration of a large number of ALS subsystems. By focusing control actions at different levels of detail and reactivity we can use faster: simpler responses at the lowest level and predictive but complex responses at the higher levels of abstraction. In particular, methods from model-based planning and scheduling can provide effective resource management over long time periods. We describe reference implementation of an advanced control system using the IDEA control architecture developed at NASA Ames Research Center. IDEA uses planning/scheduling as the sole reasoning method for predictive and reactive closed loop control. We describe preliminary experiments in planner-based control of ALS carried out on an integrated ALS simulation developed at NASA Johnson Space Center.

  10. Empirical modeling of environment-enhanced fatigue crack propagation in structural alloys for component life prediction

    Science.gov (United States)

    Richey, Edward, III

    1995-01-01

    This research aims to develop the methods and understanding needed to incorporate time and loading variable dependent environmental effects on fatigue crack propagation (FCP) into computerized fatigue life prediction codes such as NASA FLAGRO (NASGRO). In particular, the effect of loading frequency on FCP rates in alpha + beta titanium alloys exposed to an aqueous chloride solution is investigated. The approach couples empirical modeling of environmental FCP with corrosion fatigue experiments. Three different computer models have been developed and incorporated in the DOS executable program. UVAFAS. A multiple power law model is available, and can fit a set of fatigue data to a multiple power law equation. A model has also been developed which implements the Wei and Landes linear superposition model, as well as an interpolative model which can be utilized to interpolate trends in fatigue behavior based on changes in loading characteristics (stress ratio, frequency, and hold times).

  11. In silico network topology-based prediction of gene essentiality

    CERN Document Server

    da Silva, Joao Paulo Muller; Mombach, Jose Carlos Merino; Vieira, Renata; da Silva, Jose Guliherme Camargo; Lemke, Ney; Sinigaglia, Marialva

    2007-01-01

    The identification of genes essential for survival is important for the understanding of the minimal requirements for cellular life and for drug design. As experimental studies with the purpose of building a catalog of essential genes for a given organism are time-consuming and laborious, a computational approach which could predict gene essentiality with high accuracy would be of great value. We present here a novel computational approach, called NTPGE (Network Topology-based Prediction of Gene Essentiality), that relies on network topology features of a gene to estimate its essentiality. The first step of NTPGE is to construct the integrated molecular network for a given organism comprising protein physical, metabolic and transcriptional regulation interactions. The second step consists in training a decision tree-based machine learning algorithm on known essential and non-essential genes of the organism of interest, considering as learning attributes the network topology information for each of these genes...

  12. A case study of remaining storage life prediction using stochastic filtering with the influence of condition monitoring

    International Nuclear Information System (INIS)

    Some systems may spend most of their time in storage, but once needed, must be fully functional. Slow degradation occurs when the system is in storage, so to ensure the functionality of these systems, condition monitoring is usually conducted periodically to check the condition of the system. However, taking the condition monitoring data may require putting the system under real testing situation which may accelerate the degradation, and therefore, shorten the storage life of the system. This paper presents a case study of condition-based remaining storage life prediction for gyros in the inertial navigation system on the basis of the condition monitoring data and the influence of the condition monitoring data taking process. A stochastic-filtering-based degradation model is developed to incorporate both into the prediction of the remaining storage life distribution. This makes the predicted remaining storage life depend on not only the condition monitoring data but also the testing process of taking the condition monitoring data, which the existing prognostic techniques and algorithms did not consider. The presented model is fitted to the real condition monitoring data of gyros testing using the maximum likelihood estimation method for parameter estimation. Comparisons are made with the model without considering the process of taking the condition monitoring data, and the results clearly demonstrate the superiority of the newly proposed model

  13. Life prediction of coated and uncoated metallic interconnect for solid oxide fuel cell applications

    Science.gov (United States)

    Liu, W. N.; Sun, X.; Stephens, E.; Khaleel, M. A.

    In this paper, we present an integrated experimental and modeling methodology in predicting the life of coated and uncoated metallic interconnect (IC) for solid oxide fuel cell (SOFC) applications. The ultimate goal is to provide cell designer and manufacture with a predictive methodology such that the life of the IC system can be managed and optimized through different coating thickness to meet the overall cell designed life. Crofer 22 APU is used as the example IC material system. The life of coated and uncoated Crofer 22 APU under isothermal cooling was predicted by comparing the predicted interfacial strength and the interfacial stresses induced by the cooling process from the operating temperature to room temperature, together with the measured oxide scale growth kinetics. It was found that the interfacial strength between the oxide scale and the Crofer 22 APU substrate decreases with the growth of the oxide scale, and that the interfacial strength for the oxide scale/spinel coating interface is much higher than that of the oxide scale/Crofer 22 APU substrate interface. As expected, the predicted life of the coated Crofer 22 APU is significantly longer than that of the uncoated Crofer 22 APU.

  14. Validation of Framework Code Approach to a Life Prediction System for Fiber Reinforced Composites

    Science.gov (United States)

    Gravett, Phillip

    1997-01-01

    The grant was conducted by the MMC Life Prediction Cooperative, an industry/government collaborative team, Ohio Aerospace Institute (OAI) acted as the prime contractor on behalf of the Cooperative for this grant effort. See Figure I for the organization and responsibilities of team members. The technical effort was conducted during the period August 7, 1995 to June 30, 1996 in cooperation with Erwin Zaretsky, the LERC Program Monitor. Phil Gravett of Pratt & Whitney was the principal technical investigator. Table I documents all meeting-related coordination memos during this period. The effort under this grant was closely coordinated with an existing USAF sponsored program focused on putting into practice a life prediction system for turbine engine components made of metal matrix composites (MMC). The overall architecture of the NMC life prediction system was defined in the USAF sponsored program (prior to this grant). The efforts of this grant were focussed on implementing and tailoring of the life prediction system, the framework code within it and the damage modules within it to meet the specific requirements of the Cooperative. T'he tailoring of the life prediction system provides the basis for pervasive and continued use of this capability by the industry/government cooperative. The outputs of this grant are: 1. Definition of the framework code to analysis modules interfaces, 2. Definition of the interface between the materials database and the finite element model, and 3. Definition of the integration of the framework code into an FEM design tool.

  15. Review of creep–fatigue endurance and life prediction of 316 stainless steels

    International Nuclear Information System (INIS)

    The effects of different factors on the creep–fatigue endurance of 316 stainless steel are reviewed in this paper. The factors include hold period, strain range, stress range at half-life and stress relaxation behavior. The strength and limitation of different creep–fatigue life prediction methods are also summarized from the available data. It is found that each method shows some agreement with prediction with a specific set of testing data. Standard deviations of different prediction methods are calculated to evaluate the prediction capacity of these methods. It is showed that ductility exhaustion model exhibits highest accuracy at two different temperatures. - Highlights: • Effects of different factors on the creep–fatigue endurance of 316 SS are reviewed. • Tensile hold period produces more damage than compressive hold period of 316 SS. • The 316 SS exhibits cyclic-hardening characteristics under creep–fatigue conditions. • Different creep–fatigue life prediction methods are summarized. • The creep–fatigue life prediction capacities are evaluated

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

    Science.gov (United States)

    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.

  17. TBCs for Gas Turbines under Thermomechanical Loadings: Failure Behaviour and Life Prediction

    Science.gov (United States)

    Beck, T.; Trunova, O.; Herzog, R.; Singheiser, L.

    2012-10-01

    The present contribution gives an overview about recent research on a thermal barrier coating (TBC) system consisted of (i) an intermetallic MCrAlY-alloy Bondcoat (BC) applied by vacuum plasma spraying (VPS) and (ii) an Yttria Stabilised Zirconia (YSZ) top coat air plasma sprayed (APS) at Forschungszentrum Juelich, Institute of Energy and Climate Research (IEK-1). The influence of high temperature dwell time, maximum and minimum temperature on crack growth kinetics during thermal cycling of such plasma sprayed TBCs is investigated using infrared pulse thermography (IT), acoustic emission (AE) analysis and scanning electron microscopy. Thermocyclic life in terms of accumulated time at maximum temperature decreases with increasing high temperature dwell time and increases with increasing minimum temperature. AE analysis proves that crack growth mainly occurs during cooling at temperatures below the ductile-to-brittle transition temperature of the BC. Superimposed mechanical load cycles accelerate delamination crack growth and, in case of sufficiently high mechanical loadings, result in premature fatigue failure of the substrate. A life prediction model based on TGO growth kinetics and a fracture mechanics approach has been developed which accounts for the influence of maximum and minimum temperature as well as of high temperature dwell time with good accuracy in an extremely wide parameter range.

  18. Study on creep damage and life prediction of threaded connections at high temperature

    Directory of Open Access Journals (Sweden)

    Qingmin Yu

    2016-01-01

    Full Text Available In this study, Kachanov–Rabotnov model and stress relaxation damage constitutive equations deduced from Kachanov–Rabotnov model were applied to analyze the creep damage and to predict life for threaded connection structure at high temperature with finite element method. The parameters of Kachanov–Rabotnov model were obtained by fitting the results of creep experiments for titanium alloy at 650°C. Based on the experimental and finite element analysis results for standard specimen, a creep failure criterion was established. Then the influences of the external tensile load on the creep damage and life, as well as the stress relaxation on the initial preload, were studied. The analysis of stress relaxation for bolt shows that the stress relaxation has a remarkable effect on the bolt preload. The preloads decrease to a determined value with creep time and remain almost unchanged later. When the determined value is less than the required preload acting on the bolt, the structure will fail due to insufficient preload caused by stress relaxation.

  19. A prediction of biaxial fatigue life of cast stainless steels(CF8M) by degradation

    International Nuclear Information System (INIS)

    The multiaxial fatigue test under in-phase and out-of-phase load were performed to study what degradation phenomenon affects fatigue life with virgin and 3600 hrs degraded materials. The various kind of fatigue data for fatigue life prediction were acquired under pure axial and pure torsional load of fully reversal condition. The models which was investigated are: 1) the von Mises equivalent strain range, 2) the critical shear plane approach method of Fatemi-Socie(FS) parameter, 3) the modified Smith-Watson-Topper(SWT) parameter. The result showed that, fatigue life by material degradation are decreased and life prediction which was used the FS parameter is not conservative but the best result

  20. Creep-fatigue life prediction for different heats of Type 304 stainless steel by linear-damage rule, strain-range partitioning method, and damage-rate approach

    Energy Technology Data Exchange (ETDEWEB)

    Maiya, P.S.

    1978-07-01

    The creep-fatigue life results for five different heats of Type 304 stainless steel at 593/sup 0/C (1100/sup 0/F), generated under push-pull conditions in the axial strain-control mode, are presented. The life predictions for the various heats based on the linear-damage rule, strain-range partitioning method, and damage-rate approach are discussed. The appropriate material properties required for computation of fatigue life are also included.

  1. Machine performance degradation assessment and remaining useful life prediction using proportional hazard model and support vector machine

    OpenAIRE

    Tran, Tung; Pham, Hong Thom; Yang, Bo-Suk; Nguyen, Tan Tien

    2012-01-01

    Machine performance degradation assessment and remaining useful life (RUL) prediction are of crucial importance in condition-based maintenance to reduce the maintenance cost and improve the reliability. They provide a potent tool for operators in decision-making by specifying the present machine state and estimating the remaining time. For this ultimate purpose, a three-stage method for assessing the machine health degradation and forecasting the RUL is proposed. In the first stage, only the ...

  2. A New Approach for Reliability Life Prediction of Rail Vehicle Axle by Considering Vibration Measurement

    Directory of Open Access Journals (Sweden)

    Meral Bayraktar

    2014-01-01

    Full Text Available The effect of vibration on the axle has been considered. Vibration measurements at different speeds have been performed on the axle of a running rail vehicle to figure out displacement, acceleration, time, and frequency response. Based on the experimental works, equivalent stress has been used to find out life of the axles for 90% and 10% reliability. Calculated life values of the rail vehicle axle have been compared with the real life data and it is found that the life of a vehicle axle taking into account the vibration effects is in good agreement with the real life of the axle.

  3. Wavelet-based prediction of oil prices

    Energy Technology Data Exchange (ETDEWEB)

    Yousefi, Shahriar [Econometric Group, Department of Economics, University of Southern Denmark, DK-5230 Odense M (Denmark); Weinreich, Ilona [Department of Mathematics and Technology, University of Applied Sciences Koblenz, RheinAhr Campus, D-53424 Remagen (Germany)]. E-mail: weinreich@rheinahrcampus.de; Reinarz, Dominik [Department of Mathematics and Technology, University of Applied Sciences Koblenz, RheinAhr Campus, D-53424 Remagen (Germany)

    2005-07-01

    This paper illustrates an application of wavelets as a possible vehicle for investigating the issue of market efficiency in futures markets for oil. The paper provides a short introduction to the wavelets and a few interesting wavelet-based contributions in economics and finance are briefly reviewed. A wavelet-based prediction procedure is introduced and market data on crude oil is used to provide forecasts over different forecasting horizons. The results are compared with data from futures markets for oil and the relative performance of this procedure is used to investigate whether futures markets are efficiently priced.

  4. Analytical Algorithms to Quantify the Uncertainty in Remaining Useful Life Prediction

    Science.gov (United States)

    Sankararaman, Shankar; Saxena, Abhinav; Daigle, Matthew; Goebel, Kai

    2013-01-01

    This paper investigates the use of analytical algorithms to quantify the uncertainty in the remaining useful life (RUL) estimate of components used in aerospace applications. The prediction of RUL is affected by several sources of uncertainty and it is important to systematically quantify their combined effect by computing the uncertainty in the RUL prediction in order to aid risk assessment, risk mitigation, and decisionmaking. While sampling-based algorithms have been conventionally used for quantifying the uncertainty in RUL, analytical algorithms are computationally cheaper and sometimes, are better suited for online decision-making. While exact analytical algorithms are available only for certain special cases (for e.g., linear models with Gaussian variables), effective approximations can be made using the the first-order second moment method (FOSM), the first-order reliability method (FORM), and the inverse first-order reliability method (Inverse FORM). These methods can be used not only to calculate the entire probability distribution of RUL but also to obtain probability bounds on RUL. This paper explains these three methods in detail and illustrates them using the state-space model of a lithium-ion battery.

  5. Early life stress predicts thalamic hyperconnectivity: A transdiagnostic study of global connectivity.

    Science.gov (United States)

    Philip, Noah S; Tyrka, Audrey R; Albright, Sarah E; Sweet, Lawrence H; Almeida, Jorge; Price, Lawrence H; Carpenter, Linda L

    2016-08-01

    Early life stress (ELS) is an established risk factor for psychiatric illness and is associated with altered functional connectivity within- and between intrinsic neural networks. The widespread nature of these disruptions suggests that broad imaging measures of neural connectivity, such as global based connectivity (GBC), may be particularly appropriate for studies of this population. GBC is designed to identify brain regions having maximal functional connectedness with the rest of the brain, and alterations in GBC may reflect a restriction or broadening of network synchronization. We evaluated whether ELS severity predicted GBC in a sample (N = 46) with a spectrum of ELS exposure. Participants included healthy controls without ELS, those with at least moderate ELS but without psychiatric disorders, and a group of patients with ELS- related psychiatric disorders. The spatial distribution of GBC peaked in regions of the salience and default mode networks, and ELS severity predicted increased GBC of the left thalamus (corrected p < 0.005, r = 0.498). Thalamic connectivity was subsequently evaluated and revealed reduced connectivity with the salience network, particularly the dorsal anterior cingulate cortex (corrected p < 0.005), only in the patient group. These findings support a model of disrupted thalamic connectivity in ELS and trauma-related negative affect states, and underscore the importance of a transdiagnostic, dimensional neuroimaging approach to understanding the sequelae of trauma exposure. PMID:27214526

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

    Science.gov (United States)

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

    2016-09-01

    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.

  7. Potential of artificial neural network technology for predicting shelf life of processed cheese

    Directory of Open Access Journals (Sweden)

    Sumit Goyal

    Full Text Available Radial basis (fewer neurons artificial neural network (ANN models were developed for predicting the shelf life of processed cheese stored at 7-8o C. Mean square error, root mean square error, coefficient of determination and nash - sutcliffo coefficient were applied in order to compare the prediction ability of the developed models. Soluble nitrogen, pH; standard plate count, yeast & mouldcount, and spore count were the input parameters, while sensory score was output parameter for the developed model. The developed model showed very good correlation between actual data and predicted data with high coefficient of determination and nash - sutcliffo coefficient besides low root mean square error, suggesting that the developed model is quite efficient in predicting the shelf life of processed cheese.

  8. Application and limitations on thermal and spectroscopic methods for shelf-life prediction

    International Nuclear Information System (INIS)

    In medical products, shelf-life after thermoplastic processing and sterilization is important, and ionizing radiation has become a preferred sterilization mode for medical devices. We have employed successfully thermal analytical methods to predict shelf-life for many polyolefin materials. However, as the material of construction becoming more sophisticated: multiphase alloys and blends, multi-layer constructions, etc., issues existed that require clarification as to what extent these methodologies are applicable. We have employed thermal analytical methods in conjunction with other spectroscopic and morphological methods to study the applicability and limitation of these techniques. Results combined with real life and simulated aging experiments will be presented in this article

  9. Yarn Properties Prediction Based on Machine Learning Method

    Institute of Scientific and Technical Information of China (English)

    YANG Jian-guo; L(U) Zhi-jun; LI Bei-zhi

    2007-01-01

    Although many works have been done to constructprediction models on yarn processing quality, the relationbetween spinning variables and yam properties has not beenestablished conclusively so far. Support vector machines(SVMs), based on statistical learning theory, are gainingapplications in the areas of machine learning and patternrecognition because of the high accuracy and goodgeneralization capability. This study briefly introduces theSVM regression algorithms, and presents the SVM basedsystem architecture for predicting yam properties. Model.selection which amounts to search in hyper-parameter spaceis performed for study of suitable parameters with grid-research method. Experimental results have been comparedwith those of artificial neural network(ANN) models. Theinvestigation indicates that in the small data sets and real-life production, SVM models are capable of remaining thestability of predictive accuracy, and more suitable for noisyand dynamic spinning process.

  10. LINEAR LAYER AND GENERALIZED REGRESSION COMPUTATIONAL INTELLIGENCE MODELS FOR PREDICTING SHELF LIFE OF PROCESSED CHEESE

    OpenAIRE

    Goyal, S; Goyal, G. K.

    2012-01-01

    This paper highlights the significance of computational intelligence models for predicting shelf life of processed cheese stored at 7-8 g.C. Linear Layer and Generalized Regression models were developed with input parameters: Soluble nitrogen, pH, Standard plate count, Yeast & mould count, Spores, and sensory score as output parameter. Mean Square Error, Root Mean Square Error, Coefficient of Determination and Nash - Sutcliffo Coefficient were used in order to compare the prediction ability o...

  11. Predictions for fatigue crack growth life of cracked pipes and pipe welds using RMS SIF approach and experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Arora, Punit, E-mail: punit@barc.gov.in [Bhabha Atomic Research Centre, Department of Atomic Energy, Maharashtra, Mumbai 400 085 (India); Singh, P.K.; Bhasin, Vivek; Vaze, K.K.; Ghosh, A.K. [Bhabha Atomic Research Centre, Department of Atomic Energy, Maharashtra, Mumbai 400 085 (India); Pukazhendhi, D.M.; Gandhi, P.; Raghava, G. [Structural Engineering Research Centre, Chennai 600 113 (India)

    2011-10-15

    The objective of the present study is to understand the fatigue crack growth behavior in austenitic stainless steel pipes and pipe welds by carrying out analysis/predictions and experiments. The Paris law has been used for the prediction of fatigue crack growth life. To carry out the analysis, Paris constants have been determined for pipe (base) and pipe weld materials by using Compact Tension (CT) specimens machined from the actual pipe/pipe weld. Analyses have been carried out to predict the fatigue crack growth life of the austenitic stainless steel pipes/pipes welds having part through cracks on the outer surface. In the analyses, Stress Intensity Factors (K) have been evaluated through two different schemes. The first scheme considers the 'K' evaluations at two points of the crack front i.e. maximum crack depth and crack tip at the outer surface. The second scheme accounts for the area averaged root mean square stress intensity factor (K{sub RMS}) at deepest and surface points. Crack growth and the crack shape with loading cycles have been evaluated. In order to validate the analytical procedure/results, experiments have been carried out on full scale pipe and pipe welds with part through circumferential crack. Fatigue crack growth life evaluated using both schemes have been compared with experimental results. Use of stress intensity factor (K{sub RMS}) evaluated using second scheme gives better fatigue crack growth life prediction compared to that of first scheme. Fatigue crack growth in pipe weld (Gas Tungsten Arc Welding) can be predicted well using Paris constants of base material but prediction is non-conservative for pipe weld (Shielded Metal Arc Welding). Further, predictions using fatigue crack growth rate curve of ASME produces conservative results for pipe and GTAW pipe welds and comparable results for SMAW pipe welds. - Highlights: > Predicting fatigue crack growth of Austenitic Stainless Steel pipes and pipe welds. > Use of RMS-SIF and

  12. Long-term Creep Life Prediction and Its Reliability on HAZ Failure Data of Grade 91 Steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Woo Gon; Jang, Jin Sung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Jae Young [Pukyong National University, Busan (Korea, Republic of)

    2015-10-15

    Long-term creep life prediction on Grade 91 HAZ failure data was performed by LM parameter, and its reliability was successfully demonstrated using SCRI model based on Z-parameter. To improve the creep life prediction at the low stress range of high temperature range, the master curve with a 'sinh' function was newly proposed. By Monte-Carlo simulation, reliability assessment was made using the chosen service temperature and stress conditions. carbide/nitride forming elements such as V and Nb along with controlled addition of N in the plain 9Cr. 1Mo steel, offers a good combination of high creep strength and ductility over prolonged exposures at elevated temperatures. The choice of Gr. 91 steel for sodium-cooled fast reactor (SFR) applications is guided by its low thermal expansion coefficient and high resistance to stress corrosion cracking in water-steam systems compared to austenitic stainless steels.

  13. End-of-life vehicle recycling based on disassembly

    Institute of Scientific and Technical Information of China (English)

    WANG Xiang; QIN Ye; CHEN Ming; WANG Cheng-tao

    2005-01-01

    The end-of-life vehicle recycling was studied based on the disassembly. The end-of-life recycling and the disassembly were reviewed and discussed. A disassembly experiment of an end-of-life engine was carried out, which strictly recorded the process of dismantling. Based on the results, a model of the end-of-life recycling was presented. In this model, the end-of-life parts were classified by three ways which included to recycle directly, to recycleafter remanufacturing and to discard. By using this model, the dismantling efficiency and the recycling rate can be improved. Also, it obtains a good result after used in a dismantling factory.

  14. Methodology for designing accelerated aging tests for predicting life of photovoltaic arrays

    Science.gov (United States)

    Gaines, G. B.; Thomas, R. E.; Derringer, G. C.; Kistler, C. W.; Bigg, D. M.; Carmichael, D. C.

    1977-01-01

    A methodology for designing aging tests in which life prediction was paramount was developed. The methodology builds upon experience with regard to aging behavior in those material classes which are expected to be utilized as encapsulant elements, viz., glasses and polymers, and upon experience with the design of aging tests. The experiences were reviewed, and results are discussed in detail.

  15. Pre-transplant quality of life does not predict survival after lung transplantation

    NARCIS (Netherlands)

    Vermeulen, Karin M.; TenVergert, Elisabeth M.; Verschuuren, Erik A. M.; Erasmus, Michiel E.; van der Bij, Wim

    2008-01-01

    Background: Currently, the goal of lung transplantation is not only to improve survival but also includes' improvement of health-related quality of life (HRQL). Limited knowledge is available about the value of HRQL before lung transplantation with regard to predicting survival after lung transplant

  16. Illness cognitions in head and neck squamous cell carcinoma: Predicting quality of life outcome

    NARCIS (Netherlands)

    M. Scharloo (Margreet); R.J.B. de Jong; T.P.M. Langeveld (ton); E. van Velzen-Verkaik (Els); M.M. den Doorn-op den Akker (Margreet); A.A. Kaptein (Adrian)

    2010-01-01

    textabstractGoals of work: This paper presents an observational study of the longitudinal effects of cancer treatment on quality of life (QoL) in patients treated for head and neck squamous cell carcinoma (HNSCC), and evaluated the contribution of patients' baseline illness cognitions to the predict

  17. The Level of Quality of Work Life to Predict Work Alienation

    Science.gov (United States)

    Erdem, Mustafa

    2014-01-01

    The current research aims to determine the level of elementary school teachers' quality of work life (QWL) to predict work alienation. The study was designed using the relational survey model. The research population consisted of 1096 teachers employed at 25 elementary schools within the city of Van in the academic year 2010- 2011, and 346…

  18. Service Life Prediction of Wood Claddings by in-situ Measurement of Wood Moisture Content

    DEFF Research Database (Denmark)

    Engelund, Emil Tang; Lindegaard, Berit; Morsing, Niels

    2009-01-01

    of wood moisture are done by in-situ resistance moisture meters (Lindegaard and Morsing 2006). The aim is that the test should form the basis of evaluation of the maintenance requirements and the prediction of service life of the surface treatment and the wood/construction. At the moment 60 test racks...

  19. Numerical Analysis of Rolling Contact Fatigue Crack Initiation and Fatigue Life Prediction of the Railway Crossing

    NARCIS (Netherlands)

    Xin, L.; Markine, V.L.; Shevtsov, I.

    2015-01-01

    The procedure for analysing rolling contact fatigue crack initiation and fatigue life prediction of the railway turnout crossing is developed. A three-dimensional finite element (FE) model is used to obtain stress and strain results, considering the dynamic effects of wheel-crossing rolling contact.

  20. The Role of Life Satisfaction and Parenting Styles in Predicting Delinquent Behaviors among High School Students

    Science.gov (United States)

    Onder, Fulya Cenkseven; Yilmaz, Yasin

    2012-01-01

    The purpose of this study is to determine whether the parenting styles and life satisfaction predict delinquent behaviors frequently or not. Firstly the data were collected from 471 girls and 410 boys, a total of 881 high school students. Then the research was carried out with 502 students showing low (n = 262, 52.2%) and high level of delinquent…

  1. Fatigue life prediction in composites using progressive damage modelling under block and spectrum loading

    DEFF Research Database (Denmark)

    Passipoularidis, Vaggelis; Philippidis, T.P.; Brøndsted, Povl

    2010-01-01

    series can be simulated. The predictions are validated against fatigue life data both from repeated block tests at a single stress ratio as well as against spectral fatigue using the WISPER, WISPERX and NEW WISPER load sequences on a Glass/Epoxy multidirectional laminate typical of a Wind Turbine Rotor...

  2. Finite Element Creep Damage Analyses and Life Prediction of P91 Pipe Containing Local Wall Thinning Defect

    Science.gov (United States)

    Xue, Jilin; Zhou, Changyu

    2016-03-01

    Creep continuum damage finite element (FE) analyses were performed for P91 steel pipe containing local wall thinning (LWT) defect subjected to monotonic internal pressure, monotonic bending moment and combined internal pressure and bending moment by orthogonal experimental design method. The creep damage lives of pipe containing LWT defect under different load conditions were obtained. Then, the creep damage life formulas were regressed based on the creep damage life results from FE method. At the same time a skeletal point rupture stress was found and used for life prediction which was compared with creep damage lives obtained by continuum damage analyses. From the results, the failure lives of pipe containing LWT defect can be obtained accurately by using skeletal point rupture stress method. Finally, the influence of LWT defect geometry was analysed, which indicated that relative defect depth was the most significant factor for creep damage lives of pipe containing LWT defect.

  3. The new approach to residual life time prediction of power plant steam pipe lines

    International Nuclear Information System (INIS)

    Most of the known approaches for evaluation of power plant materials workability are based on the parameters of high-temperature strength and regularities of damage development due to creep. At the same time, so called low-strain failure is hardly predictable and therefore especially dangerous. The estimation of steel properties under the operational conditions and the factographic expertise of power equipment operating damage allow to consider hydrogen to be responsible for low-strain failure. This work is extension of investigation, presented on the 22th MPA-Seminar, and directed on creation of experimental procedure for the in-laboratory simulation of steel microstructural degradation, occurring under long-term operational conditions, investigation of microstructural changes in steam pipe line steel during service and at in-laboratory conditions, development of fatigue fracture mechanics approach to the evaluation of material damage, determination of hydrogen role in high-temperature ageing in steels and creation on this base the method of residual life time evaluation. (orig.)

  4. An Efficient Deterministic Approach to Model-based Prediction Uncertainty

    Data.gov (United States)

    National Aeronautics and Space Administration — Prognostics deals with the prediction of the end of life (EOL) of a system. EOL is a random variable, due to the presence of process noise and uncertainty in the...

  5. PREDICTION OF FATIGUE LIFE FOR WELDED T-JOINTS OF CONCRETE-FILLED CIRCULAR HOLLOW SECTIONS BASED ON FRACTURE MECHANICS%基于断裂力学的圆钢管混凝土T型焊接节点疲劳寿命预测

    Institute of Scientific and Technical Information of China (English)

    童乐为; 顾敏; 朱俊; 王柯

    2013-01-01

    该文应用线弹性断裂力学基本原理预测圆钢管混凝土桁架焊接T型节点的疲劳寿命.首先,进行了一些节点的疲劳试验,作为验证节点疲劳寿命预测是否可靠的参考数据;其次,建立了基于断裂力学的疲劳寿命数值模拟的模型和流程框图,采用ANSYS软件编制了APDL宏命令,实现了节点疲劳寿命的计算;最后,分析了节点疲劳裂纹的扩展特性.研究结果表明:断裂力学数值模型能较好地预测这种复杂的钢混组合节点的疲劳寿命;在正常的焊接质量条件下,不同的初始裂纹尺度对节点疲劳扩展寿命的影响不大;裂纹在长度方向的扩展速度大于在深度方向的扩展速度;裂纹深度在达到1/2主管壁厚之前,裂纹沿深度方向的扩展非常缓慢,大部分的疲劳寿命消耗在此阶段,之后裂纹沿深度方向的扩展较快.%The basic theory of linear elastic fracture mechanics was used to predict the fatigue life of welded T-joints in concrete-filled steel circular hollow section trusses. Firstly, some fatigue tests of the joints was carried out, which would be reference data for the validation of fatigue life prediction. Secondly, a model and a flowchart were set up for the numerical simulation of fatigue life based on fracture mechanics. APDL macro commands were developed by means of the software ANSYS, and then the prediction of fatigue life of the joints was implemented. Finally, the behavior of fatigue crack propagation was investigated. It is concluded that the numerical model based on fracture mechanics can better predict the fatigue life of complicated steel-concrete composite joints. The different size of an initial crack does not cause a significant influence in the condition of normal welding quality. The rate of crack propagation in length is faster than that in depth. Before the depth of a crack come to a half of the chord thickness, the crack propagates quite slowly in depth and a large

  6. Optimism and prostate cancer-specific expectations predict better quality of life after robotic prostatectomy.

    Science.gov (United States)

    Thornton, Andrea A; Perez, Martin A; Oh, Sindy; Crocitto, Laura

    2012-06-01

    We examined the relations among generalized positive expectations (optimism), prostate-cancer specific expectations, and prostate cancer-related quality of life in a prospective sample of 83 men who underwent robotic assisted laparoscopic prostatectomy (RALP) for prostate cancer. Optimism was significantly associated with higher prostate cancer-specific expectations, β = .36, p predictors of better scores on the following prostate cancer-related quality of life scales: Sexual Intimacy and Sexual Confidence; Masculine Self-Esteem (specific expectations only), Health Worry, Cancer Control, and Informed Decision Making (βs > .21, ps predictor of better Sexual Intimacy and Sexual Confidence scores, and specific expectations uniquely predicted higher scores on Informed Decision Making. Although optimism and prostate-cancer specific expectations are related, they contribute uniquely to several prostate cancer-related quality of life outcomes following RALP and may be important targets for quality of life research with this population. PMID:22051931

  7. Prediction of the fatigue life distribution for aluminum through its mechanical characteristics

    Science.gov (United States)

    Ramadan, S. Z.; Zaid, Adnan I. O.

    2016-08-01

    A novel and reliable theoretical model based on the Birnbaum-Saunders (BISA) distribution is presented from which the fatigue life can be determined. Experimental verification of the model is in progress and will be published in due course.

  8. Colored Noise Prediction Based on Neural Network

    Institute of Scientific and Technical Information of China (English)

    Gao Fei; Zhang Xiaohui

    2003-01-01

    A method for predicting colored noise by introducing prediction of nonhnear time series is presented By adopting three kinds of neural networks prediction models, the colored noise prediction is studied through changing the filter bandwidth for stochastic noise and the sampling rate for colored noise The results show that colored noise can be predicted The prediction error decreases with the increasing of the sampling rate or the narrowing of the filter bandwidth. If the parameters are selected properly, the prediction precision can meet the requirement of engineering implementation. The results offer a new reference way for increasing the ability for detecting weak signal in signal processing system

  9. Prediction of Storage Life of Propellants having Different Burning Rates using Dynamic Mechanical Analysis

    Directory of Open Access Journals (Sweden)

    V.S. Wani

    2012-09-01

    Full Text Available Propellants, visco-elastic in nature, show time and temperature dependent behaviour on deformation. Hence, the time–temperature superposition principle may be applied to the visco-elastic properties of propellants. In the present study, dynamic mechanical analyser (DMA was used to evaluate the dynamic mechanical properties and quantify the storage life of four different propellants based on hydroxyl terminated polybutadiene, aluminium and ammonium perchlorate having different burning rates ranging from 5 mm/s to 25 mm/s. Each sample was given a multi-frequency strain of 0.01 per cent at three discrete frequencies (3.5 Hz, 11 Hz, 35 Hz in the temperature range - 80 °C to + 80 °C. The storage modulus, loss modulus, tan delta and glass transition temperature (Tg for each propellant samples have been evaluated and it is observed that all the propellants have shown time (frequency and temperature dependent behaviour on deformation. A comparison of the log aT versus temperature curves (where aT is horizontal (or time shift factor for all four propellants indicate conformance to the Williams–Landel–Ferry (WLF equation. The master curves of storage modulus (log É versus log ω plots were generated for each propellant. A plot of É versus time for all propellants was generated up to 3 years, 6 years, and 10 years of time, respectively. The drop in the storage modulus below the acceptable limit with time may be used to predict the shelf life of the propellant.Defence Science Journal, 2012, 62(5, pp.290-294, DOI:http://dx.doi.org/10.14429/dsj.62.2480

  10. Weather, knowledge base and life-style

    Science.gov (United States)

    Bohle, Martin

    2015-04-01

    Why to main-stream curiosity for earth-science topics, thus to appraise these topics as of public interest? Namely, to influence practices how humankind's activities intersect the geosphere. How to main-stream that curiosity for earth-science topics? Namely, by weaving diverse concerns into common threads drawing on a wide range of perspectives: be it beauty or particularity of ordinary or special phenomena, evaluating hazards for or from mundane environments, or connecting the scholarly investigation with concerns of citizens at large; applying for threading traditional or modern media, arts or story-telling. Three examples: First "weather"; weather is a topic of primordial interest for most people: weather impacts on humans lives, be it for settlement, for food, for mobility, for hunting, for fishing, or for battle. It is the single earth-science topic that went "prime-time" since in the early 1950-ties the broadcasting of weather forecasts started and meteorologists present their work to the public, daily. Second "knowledge base"; earth-sciences are a relevant for modern societies' economy and value setting: earth-sciences provide insights into the evolution of live-bearing planets, the functioning of Earth's systems and the impact of humankind's activities on biogeochemical systems on Earth. These insights bear on production of goods, living conditions and individual well-being. Third "life-style"; citizen's urban culture prejudice their experiential connections: earth-sciences related phenomena are witnessed rarely, even most weather phenomena. In the past, traditional rural communities mediated their rich experiences through earth-centric story-telling. In course of the global urbanisation process this culture has given place to society-centric story-telling. Only recently anthropogenic global change triggered discussions on geoengineering, hazard mitigation, demographics, which interwoven with arts, linguistics and cultural histories offer a rich narrative

  11. Predictive Modeling for End-of-Life Pain Outcome using Electronic Health Records

    Science.gov (United States)

    Lodhi, Muhammad K.; Stifter, Janet; Yao, Yingwei; Ansari, Rashid; Kee-nan, Gail M.; Wilkie, Diana J.; Khokhar, Ashfaq A.

    2016-01-01

    Electronic health record (EHR) systems are being widely used in the healthcare industry nowadays, mostly for monitoring the progress of the patients. EHR data analysis has become a big data problem as data is growing rapidly. Using a nursing EHR system, we built predictive models for determining what factors influence pain in end-of-life (EOL) patients. Utilizing different modeling techniques, we developed coarse-grained and fine-grained models to predict patient pain outcomes. The coarse-grained models help predict the outcome at the end of each hospitalization, whereas fine-grained models help predict the outcome at the end of each shift, thus providing a trajectory of predicted outcomes over the entire hospitalization. These models can help in determining effective treatments for individuals and groups of patients and support standardization of care where appropriate. Using these models may also lower the cost and increase the quality of end-of-life care. Results from these techniques show significantly accurate predictions.

  12. A new simplified allometric approach for predicting the biological half-life of radionuclides in reptiles

    International Nuclear Information System (INIS)

    A major source of uncertainty in the estimation of radiation dose to wildlife is the prediction of internal radionuclide activity concentrations. Allometric (mass-dependent) relationships describing biological half-life (T1/2b) of radionuclides in organisms can be used to predict organism activity concentrations. The establishment of allometric expressions requires experimental data which are often lacking. An approach to predict the T1/2b in homeothermic vertebrates has recently been proposed. In this paper we have adapted this to be applicable to reptiles. For Cs, Ra and Sr, over a mass range of 0.02–1.5 kg, resultant predictions were generally within a factor of 6 of reported values demonstrating that the approach can be used when measured T1/2b data are lacking. However, the effect of mass on reptilian radionuclide T1/2b is minimal. If sufficient measured data are available for a given radionuclide then it is likely that these would give a reasonable estimate of T1/2b in any reptile species. - Highlights: • An allometric approach to predict radionuclide T1/2b values in reptiles is derived. • Predictions are generally within a factor of six of measured values. • Radionuclide biological half-life is in-effect mass independent

  13. Research on Fatigue Life Prediction of Gear Box in Caterpillar based on Running Simulation Test%基于行驶仿真试验的履带车辆传动箱疲劳寿命预测仿真研究

    Institute of Scientific and Technical Information of China (English)

    刁哲军; 杜秀菊; 张艳华; 范书果; 贾长治

    2011-01-01

    履带车辆传动箱在设计时采用静强度设计理论,由于无法准确反映其在不同任务工况下的各组成部件动态特性,同时由于传统测试手段及试验方法的局限性,使对随机载荷作用下的各组成部件的可靠性及寿命预测研究具有很大困难,导致实际寿命与设计寿命有很大差距,严重影响了履带车辆整车可靠性.通过建立基于MSC.ATV的行驶仿真试验平台,获得了履带车辆传动箱各零部件在不同工况所承受的实际载荷,并将其作用于所建立的传动箱疲劳寿命预测系统,获得了传动箱关重件的疲劳寿命.用传动箱齿轮的疲劳寿命预测实例证明了所构建的基于行驶仿真试验的疲劳寿命预测方法的可行性.%Gear box in caterpillar is designed with the static strength theory.While the dynamic characteristics of planetary parts in different working condition is difficult to obtain with the limit of traditional method, so research on reliability and fatigue life prediction of gear box is very difficulty which result that designed life is much longer than practical life.The reliability of caterpillar is affected deeply.The dynamic loads suffered by gear box in different working condition is obtained based on running simulation with MSC.ATV, and then the fatigue life of planetary frame is calculated with fatigue life prediction system of gear box.The study case prove the new method is feasible.

  14. Land colonisation by fish is associated with predictable changes in life history.

    Science.gov (United States)

    Platt, Edward R M; Fowler, Ashley M; Ord, Terry J

    2016-07-01

    The colonisation of new environments is a central evolutionary process, yet why species make such transitions often remains unknown because of the difficulty in empirically investigating potential mechanisms. The most likely explanation for transitions to new environments is that doing so conveys survival benefits, either in the form of an ecological release or new ecological opportunity. Life history theory makes explicit predictions about how traits linked to survival and reproduction should change with shifts in age-specific mortality. We used these predictions to examine whether a current colonisation of land by fishes might convey survival benefits. We found that blenny species with more terrestrial lifestyles exhibited faster reproductive development and slower growth rates than species with more marine lifestyles; a life history trade off that is consistent with the hypothesis that mortality has become reduced in younger life stages on land. A plausible explanation for such a shift is that an ecological release or opportunity on land has conveyed survival benefits relative to the ancestral marine environment. More generally, our study illustrates how life history theory can be leveraged in novel ways to formulate testable predictions on why organisms might make transitions into novel environments. PMID:26932469

  15. Digital Processing Based Solutions for Life Science Engineering Recognition Problems

    OpenAIRE

    Hussein, Walid

    2013-01-01

    The field of Life Science Engineering (LSE) is rapidly expanding and predicted to grow strongly in the next decades. It covers areas of food and medical research, plant and pests’ research, and environmental research. In each research area, engineers try to find equations that model a certain life science problem. Once found, they research different numerical techniques to solve for the unknown variables of these equations. Afterwards, solution improvement is examined by adopting more accurat...

  16. Predicting Scientific Success Based on Coauthorship Networks

    CERN Document Server

    Sarigöl, Emre; Scholtes, Ingo; Garas, Antonios; Schweitzer, Frank

    2014-01-01

    We address the question to what extent the success of scientific articles is due to social influence. Analyzing a data set of over 100000 publications from the field of Computer Science, we study how centrality in the coauthorship network differs between authors who have highly cited papers and those who do not. We further show that a machine learning classifier, based only on coauthorship network centrality measures at time of publication, is able to predict with high precision whether an article will be highly cited five years after publication. By this we provide quantitative insight into the social dimension of scientific publishing - challenging the perception of citations as an objective, socially unbiased measure of scientific success.

  17. Fatigue Life Prediction of Multi Leaf Spring used in the Suspension System of Light Commercial Vehicle

    OpenAIRE

    V.K.Aher; R. A. Gujar; Wagh, J. P.; P.M.Sonawane

    2012-01-01

    The Leaf spring is widely used in automobiles and one of the components of suspension system. It needs to have high fatigue life. As a general rule, the leaf spring is regarded as a safety component as failure could lead to severe accidents. The purpose of this paper is to predict the fatigue life of steel leaf spring along with analytical stress and deflection calculations. This present work describes static and fatigue analysis of a steel leaf spring of a light commercial vehicle (LCV). Th...

  18. Effect of Notch Location on Fatigue Life Prediction of Strength Mismatched HSLA Steel Weldments

    Institute of Scientific and Technical Information of China (English)

    S. Ravi; V. Balasubramanian; S. Nemat Nasser

    2004-01-01

    Welding of high strength low alloy steels (HSLA) involves usage of Iow, even and high strength filler materials (electrodes) than the parent material depending on the application of the welded structures and the availability of the filler material. In the present investigation, the fatigue crack growth behaviour of weld metal (WM) and heat affected zone (HAZ) regions of under matched (UM), equal matched (EM) and over matched (OM)joints has been studied. The base material used in this investigation is HSLA-80 steel of weldable grade. Shielded metal arc welding (SMAW) process has been used to fabricate the butt joints. Centre cracked tension (CCT) specimen has been used to evaluate the fatigue crack growth behaviour of the welded joints. Fatigue crack growth experiments have been conducted using servo hydraulic controlled fatigue testing machine at constant amplitude loading (R=0). A method has been proposed to predict the fatigue life of HSLA steel welds using fracture mechanics approach by incorporating influences of mismatch ratio (MMR) and notch location.

  19. Slow Crack Growth and Fatigue Life Prediction of Ceramic Components Subjected to Variable Load History

    Science.gov (United States)

    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.

  20. DMC modified algorithm based on time series prediction principle

    Institute of Scientific and Technical Information of China (English)

    齐维贵; 朱学莉

    2002-01-01

    The application of heating load prediction and predictive control to the heat supply system for energysaving and high quality heat supply is discussed by first introducing the time series prediction principle, and thesequence model, parameter identification and least variance prediction principle, and then giving the heatingload and model error prediction based on this principle. As an improvement of DMC algorithm, the load predic-tion is used as a set point of DMC, and the prediction error is used as a corrected value of predictive control.Finally, the simulation results of two prediction methods to heat supply system are given.

  1. Profiling crop pollinators: life history traits predict habitat use and crop visitation by Mediterranean wild bees.

    Science.gov (United States)

    Pisanty, Gideon; Mandelik, Yael

    2015-04-01

    Wild pollinators, bees in particular, may greatly contribute to crop pollination and provide a safety net against declines in commercial pollinators. However, the identity, life history traits, and environmental sensitivities of main crop pollinator species.have received limited attention. These are crucial for predicting pollination services of different communities and for developing management practices that enhance crop pollinators. We sampled wild bees in three crop systems (almond, confection sunflower, and seed watermelon) in a mosaic Israeli Mediterranean landscape. Bees were sampled in field/orchard edges and interiors, and in seminatural scrub surrounding the fields/orchards. We also analyzed land cover at 50-2500 m radii around fields/orchards. We used this data to distinguish crop from non-crop pollinators based on a set of life history traits (nesting, lecty, sociality, body size) linked to habitat preference and crop visitation. Bee abundance and species richness decreased from the surrounding seminatural habitat to the field/orchard interior, especially across the seminatural habitat-field edge ecotone. Thus, although rich bee communities were found near fields, only small fractions crossed the ecotone and visited crop flowers in substantial numbers. The bee assemblage in agricultural fields/orchards and on crop flowers was dominated by ground-nesting bees of the tribe Halictini, which tend to nest within fields. Bees' habitat preferences were determined mainly by nesting guild, whereas crop visitation was determined mainly by sociality. Lecty and body size also affected both measures. The percentage of surrounding seminatural habitat at 250-2500 m radii had a positive effect on wild bee diversity in field edges, for all bee guilds, while at 50-100 m radii, only aboveground nesters were positively affected. In sum, we found that crop and non-crop pollinators are distinguished by behavioral and morphological traits. Hence, analysis of life

  2. Life prediction methodology for ceramic components of advanced vehicular heat engines: Volume 1. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Khandelwal, P.K.; Provenzano, N.J.; Schneider, W.E. [Allison Engine Co., Indianapolis, IN (United States)

    1996-02-01

    One of the major challenges involved in the use of ceramic materials is ensuring adequate strength and durability. This activity has developed methodology which can be used during the design phase to predict the structural behavior of ceramic components. The effort involved the characterization of injection molded and hot isostatic pressed (HIPed) PY-6 silicon nitride, the development of nondestructive evaluation (NDE) technology, and the development of analytical life prediction methodology. Four failure modes are addressed: fast fracture, slow crack growth, creep, and oxidation. The techniques deal with failures initiating at the surface as well as internal to the component. The life prediction methodology for fast fracture and slow crack growth have been verified using a variety of confirmatory tests. The verification tests were conducted at room and elevated temperatures up to a maximum of 1371 {degrees}C. The tests involved (1) flat circular disks subjected to bending stresses and (2) high speed rotating spin disks. Reasonable correlation was achieved for a variety of test conditions and failure mechanisms. The predictions associated with surface failures proved to be optimistic, requiring re-evaluation of the components` initial fast fracture strengths. Correlation was achieved for the spin disks which failed in fast fracture from internal flaws. Time dependent elevated temperature slow crack growth spin disk failures were also successfully predicted.

  3. A Novel and Simple Methodology for Predicting Creep Life of Welded Pressure Component Employing Strain Energy Density

    Science.gov (United States)

    Mahmood, T.; Kanapathipillai, S.; Chowdhury, M.

    2013-10-01

    Almost all of the pressure components produced at present are produced by welding and a good majority of them are used for high temperature application where creep damage can occur and requires the attention of the pressure equipment designers. An accurate creep life prediction model is required to predict the life of such pressure components. All of the creep life prediction models available today are either inaccurate or too cumbersome to apply. There is a need for an accurate creep life prediction model that would overcome the shortcomings of the existing models. Research team at UNSW have developed a creep life prediction model [Mahmood et al., in Front Mech Eng, 8(2):181-186, 2013; Mahmood et al., in Eng Integr J, 34:6-13, 2013; Mahmood et al. in Intl J Reliab Saf Eng Syst Struct D, 1(1):43-51, 2011] that accurately predicted the creep life of seamless pipes when applied to them. This paper is an extension of previous work and investigates the accuracy of the model when applied to a thick-walled pipe having a circumferential weld to predict the creep life of a welded pressure component. The paper shows that the proposed model can predict the creep life of the vessel with an error of less than 1 %.

  4. Prediction of service life of aircraft structural components using the half-cycle method

    Science.gov (United States)

    Ko, William L.

    1987-01-01

    The service life of aircraft structural components undergoing random stress cycling was analyzed by the application of fracture mechanics. The initial crack sizes at the critical stress points for the fatigue-crack growth analysis were established through proof load tests. The fatigue-crack growth rates for random stress cycles were calculated using the half-cycle method. A new equation was developed for calculating the number of remaining flights for the structural components. The number of remaining flights predicted by the new equation is much lower than that predicted by the conventional equation.

  5. FATIGUE LIFE PREDICTION OF COMMERCIALLY PURE TITANIUM AFTER NITROGEN ION IMPLANTATION

    Directory of Open Access Journals (Sweden)

    Nurdin Ali

    2013-06-01

    Full Text Available Prediction of fatigue life has become an interesting issue in biomaterial engineering and design for reliability and quality purposes, particularly for biometallic material with modified surfaces. Commercially pure titanium (Cp-Ti implanted with nitrogen ions is a potential metallic biomaterial of the future. The effect of nitrogen ion implantation on fatigue behavior of Cp-Ti was investigated by means of axial loading conditions. The as-received and nitrogen-ion implanted specimens with the energy of 100 keV and dose of 2 × 1017 ions cm-2, were used to determine the fatigue properties and to predict the life cycle of the specimens. The effect of nitrogen ion implantation indicated revealed improved the tensile strength due to the formation of nitride phases, TiN and Ti2N. The fatigue strength of Cp-Ti and Nii-Ti was 250 and 260 MPa, respectively. The analytical results show good agreement with experimental results.

  6. A risk-based approach to life-cycle impact assessment

    NARCIS (Netherlands)

    Assies, JA

    1998-01-01

    This paper suggests an approach to life-cycle impact assessment which is based on the comparison of predicted exploitation or pollution levels with critical levels; the latter representing the carrying capacity of the commodity-supplying or pollutant-receiving environment. The incremental pressure i

  7. SOFT COMPUTING SINGLE HIDDEN LAYER MODELS FOR SHELF LIFE PREDICTION OF BURFI

    OpenAIRE

    Sumit Goyal; Gyanendra Kumar Goyal

    2012-01-01

    Burfi is an extremely popular sweetmeat, which is prepared by desiccating the standardized water buffalo milk. Soft computing feedforward single layer models were developed for predicting the shelf life of burfi stored at 30g.C. The data of the product relating to moisture, titratable acidity, free fatty acids, tyrosine, and peroxide value were used as input variables, and the overall acceptability score as output variable. The results showed excellent agreement between the experimental and t...

  8. Multi-scale symbolic entropy analysis provides prognostic prediction in patients receiving extracorporeal life support

    OpenAIRE

    Lin, Yen-Hung; Huang, Hui-Chun; Chang, Yi-Chung; Lin, Chen; Lo, Men-Tzung; Liu, Li-Yu Daisy; Tsai, Pi-Ru; Chen, Yih-Sharng; Ko, Wen-Je; Ho, Yi-Lwun; Chen, Ming-Fong; Peng, Chung-Kang; Buchman, Timothy G.

    2014-01-01

    Introduction: Extracorporeal life support (ECLS) can temporarily support cardiopulmonary function, and is occasionally used in resuscitation. Multi-scale entropy (MSE) derived from heart rate variability (HRV) is a powerful tool in outcome prediction of patients with cardiovascular diseases. Multi-scale symbolic entropy analysis (MSsE), a new method derived from MSE, mitigates the effect of arrhythmia on analysis. The objective is to evaluate the prognostic value of MSsE in patients receiving...

  9. Multi-scale symbolic entropy analysis provides prognostic prediction in patients receiving extracorporeal life support

    OpenAIRE

    Lin, Yen-Hung; Huang, Hui-Chun; Chang, Yi-Chung; Lin, Chen; Lo, Men-Tzung; Liu, Li-Yu Daisy; Tsai, Pi-Ru; Chen, Yih-Sharng; Ko, Wen-Je; Ho, Yi-Lwun; Chen, Ming-Fong; Peng, Chung-Kang; Buchman, Timothy G.

    2014-01-01

    Introduction Extracorporeal life support (ECLS) can temporarily support cardiopulmonary function, and is occasionally used in resuscitation. Multi-scale entropy (MSE) derived from heart rate variability (HRV) is a powerful tool in outcome prediction of patients with cardiovascular diseases. Multi-scale symbolic entropy analysis (MSsE), a new method derived from MSE, mitigates the effect of arrhythmia on analysis. The objective is to evaluate the prognostic value of MSsE in patients receiving ...

  10. Modifiable and fixed factors predicting quality of life in people with colorectal cancer

    OpenAIRE

    Gray, N M; Hall, S. J.; Browne, S.; Macleod, U; Mitchell, E.; Lee, A J; Johnston, M.; Wyke, S.; Samuel, L; Weller, D.; Campbell, N C

    2011-01-01

    Background: People with colorectal cancer have impaired quality of life (QoL). We investigated what factors were most highly associated with it.Methods: Four hundred and ninety-six people with colorectal cancer completed questionnaires about QoL, functioning, symptoms, co-morbidity, cognitions and personal and social factors. Disease, treatment and co-morbidity data were abstracted from case notes. Multiple linear regression identified modifiable and unmodifiable factors independently predict...

  11. Health-Related Quality of Life and its Predictive Factors among Infertile Women

    OpenAIRE

    Mohammad Alizadeh Charandabi, Sekineh; Kamalifard, Mahin; Mahzad Sedaghiani, Mehrzad; Montazeri, Ali; Dehghanpour Mohammadian, Elham

    2012-01-01

    Introduction: The present study aimed to determine health-related quality of life (HRQOL) and its predictive factors among infertile women. Methods: This cross-sectional study was conducted on infertile women referring to Majidi Infertility Center (Tabriz, Iran). The data was collected through self-administered questionnaires including clinical and demographic characteristics and the Persian version of 36-item short form health survey (SF-36). One-sample t-test, independent ...

  12. Preadmission quality of life can predict mortality in intensive care unit—A prospective cohort study

    DEFF Research Database (Denmark)

    Bukan, Ramin I; Møller, Ann M; Henning, Mattias A S;

    2014-01-01

    PURPOSE: We sought to investigate whether preadmission quality of life could act as a predictor of mortality among patients admitted to the intensive care unit (ICU). MATERIALS AND METHODS: This is a prospective observational study of all patients above the age of 18 years admitted to the ICU...... with a length of stay longer than 24 hours. Short form 36 (SF-36) and Acute Physiology and Chronic Health Evaluation II (APACHE II) were used. Mortality was assessed during ICU admission, 30, and 90 days hereafter. RESULTS: We included 318 patients. No patients were lost to follow-up. Using the physical...... quality of life, assessed by SF-36 and SF-12, is as good at predicting ICU, 30-, and 90-day mortality as APACHE II in patients admitted to the ICU for longer than 24 hours. This indicates that estimated preadmission quality of life, potentially available in the pre-ICU setting, could aid decision making...

  13. Toward a theoretically based measurement model of the good life.

    Science.gov (United States)

    Cheung, C K

    1997-06-01

    A theoretically based conceptualization of the good life should differentiate 4 dimensions-the hedonist good life, the dialectical good life, the humanist good life, and the formalist good life. These 4 dimensions incorporate previous fragmentary measures, such as life satisfaction, depression, work alienation, and marital satisfaction, to produce an integrative view. In the present study, 276 Hong Kong Chinese husbands and wives responded to a survey of 13 indicators for these 4 good life dimensions. Confirmatory hierarchical factor analysis showed that these indicators identified the 4 dimensions of the good life, which in turn converged to identify a second-order factor of the overall good life. The model demonstrates discriminant validity in that the first-order factors had high loadings on the overall good life factor despite being linked by a social desirability factor. Analysis further showed that the second-order factor model applied equally well to husbands and wives. Thus, the conceptualization appears to be theoretically and empirically adequate in incorporating previous conceptualizations of the good life. PMID:9168589

  14. The effect of discounting, different mortality reduction schemes and predictive cohort life tables on risk acceptability criteria

    International Nuclear Information System (INIS)

    Technical facilities should be optimal with respect to benefits and cost. Optimization of technical facilities involving risks for human life and limb require an acceptability criterion and suitable discount rates both for the public and the operator depending on for whom the optimization is carried out. The life quality index is presented and embedded into modem socio-economic concepts. A general risk acceptability criterion is derived. The societal life saving cost to be used in optimization as life saving or compensation cost and the societal willingness-to-pay based on the societal value of a statistical life or on the societal life quality index are developed. Different mortality reduction schemes are studied. Also, predictive cohort life tables are derived and applied. Discount rates γ must be long-term averages in view of the time horizon of some 20 to more than 100 years for the facilities of interest and net of inflation and taxes. While the operator may use long-term averages from the financial market for his cost-benefit analysis the assessment of interest rates for investments of the public into risk reduction is more difficult. The classical Ramsey model decomposes the real interest rate (=output growth rate) into the rate of time preference of consumption and the rate of economical growth multiplied by the elasticity of marginal utility of consumption. It is proposed to use a relatively small interest rate of 3% implying a rate of time preference of consumption of about 1%. This appears intergenerationally acceptable from an ethical point of view. Risk-consequence curves are derived for an example

  15. How do Major, Violent and Nonviolent Opposition Campaigns, Impact Predicted Life Expectancy at birth?

    Directory of Open Access Journals (Sweden)

    Judith Stoddard

    2013-08-01

    Full Text Available This study compared the effects of major violent and nonviolent opposition campaigns for regime change, on predicted life expectancy at birth. The study measured life expectancy five and ten years after the campaign ended, so that deaths which occurred during the campaign would not be included in the metric, and thus enabling the study of changes made in the state on the social determinants affecting longevity, after the campaign was over. Life expectancy is one of the best reported World Development Indicators and is considered to be a good indication of the overall health and general living conditions of the state and therefore is an ideal indicator to reflect the changes made in the state following a major campaign. The results of this analysis showed that states have a hard time recovering from a major opposition campaign and initially drop behind the growth trend in the world average for predicted life expectancy at birth. But, the type of campaign that was waged and whether it was successful, greatly affects the state’s ability to recover. Encouragingly by a decade after the campaign ends, states that experienced a nonviolent campaign that was successful had caught up to the world average and inched ahead of it. This shows that on this important development indicator, new governments that were ushered into power by nonviolent social movements, had made positive changes in the state that enabled it to surpass world averages.

  16. Cultivating Life Skills at a Project-Based Charter School

    Science.gov (United States)

    Wurdinger, Scott; Enloe, Walter

    2011-01-01

    Surveys that focused on academic and life skill development were collected from alumni who attended Avalon Charter School in St Paul, Minnesota. Avalon is a small public charter school that uses project-based learning as their primary teaching method. Forty-two alumni responded to the online survey. Students ranked life skills such as creativity,…

  17. Enhancing College Students' Life Skills through Project Based Learning

    Science.gov (United States)

    Wurdinger, Scott; Qureshi, Mariam

    2015-01-01

    This study examined whether life skills could be developed in a Project Based Learning (PBL) course. The participants were students enrolled in a graduate level PBL course. The same 35-question survey was given to students at the beginning and end of the course, and students were asked to rank their life skills using a Likert scale. Additionally,…

  18. An Adaptive Recurrent Neural Network for Remaining Useful Life Prediction of Lithium-ion Batteries

    Data.gov (United States)

    National Aeronautics and Space Administration — Prognostics is an emerging science of predicting the health condition of a system (or its components) based upon current and previous system states. A reliable...

  19. 四参数疲劳定寿方法%Four-parameter life prediction method

    Institute of Scientific and Technical Information of China (English)

    宁向荣; 陈伟; 蔡显新; 廖学军; 米栋

    2012-01-01

    对直升机传动系统采用的一种疲劳定寿方法——四参数法进行了研究:首先介绍了四参数应力一循环(S—N)曲线,然后详细介绍了通过材料平均S—N曲线获取构件安全S—N曲线的步骤以及直升机传动系统四参数疲劳定寿的程序和方法,研究了定寿流程中的各个技术细节.同时介绍了传动系统机匣疲劳试验中的多路协调加载技术以及某传动系统尾减机匣(TGB)的全尺寸疲劳试验情况.最后采用四参数疲劳定寿方法,根据某传动系统尾减机匣全尺寸疲劳试验结果和飞行实测载荷谱,对尾减机匣进行了安全寿命评估.该实例分析表明:四参数疲劳定寿方法为一种有效、可靠的寿命评估方法,具有推广价值.%Four-parameter life prediction method for helicopter transmission system was studied. Four-parameter stress-number of cycles (S-N) curve was presented first, and then, the derivation of helicopter transmission component safe S-N curve from material mean S-N curve and the scheme for the component life prediction were introduced in detail. Multi-load coordinating loading technology in fatigue test and a tail gear box (TGB) casing full-scale fatigue test were introduced at the same time. Finally, according to the full-scale fatigue test result and flight load survey data, applying the four-parameter life prediction method, the TGB casing life prediction was performed, which indicates that four-parameter life prediction method is a reliable and effective method and is worth to be generalized.

  20. Fatigue, fracture, and life prediction criteria for composite materials in magnets

    International Nuclear Information System (INIS)

    An explosively-bonded copper/Inconel 718/copper laminate conductor was proposed to withstand the severe face compression stresses in the central core of the Alcator C-MOD tokamak toroidal field (TF) magnet. Due to the severe duty of the TF magnet, it is critical that an accurate estimate of useful life be determined. As part of the effort to formulate an appropriate life prediction, fatigue crack growth experiments were performed on the laminate as well as its components. Metallographic evaluation of the laminate interface revealed many shear bands in the Inconel 718. Shear bands and shear band cracks were produced in the Inconel 718 as a result of the explosion bonding process. These shear bands were shown to have a detrimental effect on the crack growth behavior of the laminate, by significantly reducing the load carrying capability of the reinforcement layer and providing for easy crack propagation paths. Fatigue crack growth rate was found not only to be dependent on temperature but also on orientation. Fatigue cracks grew faster in directions which contained shear bands in the plane of the propagating crack. Fractography showed crack advancement by fatigue cracking in the Inconel 718 and ductile tearing of the copper at the interface. However, further away from the interfaces, the copper exhibited fatigue striations indicating that cracks were now propagating by fatigue. Laminate life prediction results showed a strong dependence on shear band orientation, and exhibited little variation between room temperature and 77 degree K. Predicted life of this laminate was lower when the crack propagation was along a shear band than when crack propagation was across the shear bands. Shear bands appear to have a dominating effect on crack growth behavior

  1. Community Detection Based on Link Prediction Methods

    CERN Document Server

    Cheng, Hui-Min

    2016-01-01

    Community detection and link prediction are both of great significance in network analysis, which provide very valuable insights into topological structures of the network from diffrent perspectives. In this paper, we propose a novel community detection algorithm with inclusion of link prediction, motivated by the question whether link prediction can be devoted to improve the accuracy of community partition. For link prediction, we propose two novel indices to compute the similarity between each pair of nodes, one of which aims to add missing links, and the other tries to remove spurious edges. Extensive experiments are conducted on benchmark data sets, and the results of our proposed algorithm are compared with two classes of baselines. In conclusion, our proposed algorithm is competitive, revealing that link prediction does improve the precision of community detection.

  2. Leaf and life history traits predict plant growth in a green roof ecosystem.

    Directory of Open Access Journals (Sweden)

    Jeremy Lundholm

    Full Text Available Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime's C-S-R strategies for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that

  3. Leaf and life history traits predict plant growth in a green roof ecosystem.

    Science.gov (United States)

    Lundholm, Jeremy; Heim, Amy; Tran, Stephanie; Smith, Tyler

    2014-01-01

    Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth) to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime's C-S-R strategies) for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that favor less

  4. Leaf and life history traits predict plant growth in a green roof ecosystem.

    Science.gov (United States)

    Lundholm, Jeremy; Heim, Amy; Tran, Stephanie; Smith, Tyler

    2014-01-01

    Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth) to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime's C-S-R strategies) for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that favor less

  5. Fatigue Life Prediction of Multi Leaf Spring used in the Suspension System of Light Commercial Vehicle

    Directory of Open Access Journals (Sweden)

    V.K.Aher

    2012-06-01

    Full Text Available The Leaf spring is widely used in automobiles and one of the components of suspension system. It needs to have high fatigue life. As a general rule, the leaf spring is regarded as a safety component as failure could lead to severe accidents. The purpose of this paper is to predict the fatigue life of steel leaf spring along with analytical stress and deflection calculations. This present work describes static and fatigue analysis of a steel leaf spring of a light commercial vehicle (LCV. The dimensions of the leaf spring of a LCV are taken and are verified by design calculations. The non-linear static analysis of 2D model of the leaf spring is performed using NASTRAN solver and compared with analytical results. The preprocessing of the model is done by using HYPERMESH software. The stiffness of the leaf spring is studied by plotting load versus deflection curve for various load applications. The simulation results are compared with analytical results. The fatigue life of the leaf spring is predicted using MSC Fatigue software.

  6. Psychological approach to successful ageing predicts future quality of life in older adults

    Directory of Open Access Journals (Sweden)

    Iliffe Steve

    2011-03-01

    Full Text Available Abstract Background Public policies aim to promote well-being, and ultimately the quality of later life. Positive perspectives of ageing are underpinned by a range of appraoches to successful ageing. This study aimed to investigate whether baseline biological, psychological and social aproaches to successful ageing predicted future QoL. Methods Postal follow-up in 2007/8 of a national random sample of 999 people aged 65 and over in 1999/2000. Of 496 valid addresses of survivors at follow-up, the follow-up response rate was 58% (287. Measures of the different concepts of successful ageing were constructed using baseline indicators. They were assessed for their ability to independently predict quality of life at follow-up. Results Few respondents achieved all good scores within each of the approaches to successful ageing. Each approach was associated with follow-up QoL when their scores were analysed continuously. The biomedical (health approach failed to achieve significance when the traditional dichotomous cut-off point for successfully aged (full health, or not (less than full health, was used. In multiple regression analyses of the relative predictive ability of each approach, only the psychological approach (perceived self-efficacy and optimism retained significance. Conclusion Only the psychological approach to successful ageing independently predicted QoL at follow-up. Successful ageing is not only about the maintenance of health, but about maximising one's psychological resources, namely self-efficacy and resilience. Increasing use of preventive care, better medical management of morbidity, and changing lifestyles in older people may have beneficial effects on health and longevity, but may not improve their QoL. Adding years to life and life to years may require two distinct and different approaches, one physical and the other psychological. Follow-up health status, number of supporters and social activities, and self-rated active ageing

  7. 腐蚀管道剩余寿命预测及结构可靠度分析的VB/MATLAB程序实现%The Prediction Analysis of Remaining Life and Plane Frame Structure Displacement Reliability of Corroded Pipelines Based on VB/MATLAB

    Institute of Scientific and Technical Information of China (English)

    陈典斌; 韩东霏; 张二保; 韩岳洋; 刘诗文; 张建春

    2014-01-01

    The prediction of remaining life and analysis of plane frame structure displacement reliability pipelines with corrosion defects are not only important parts of pipeline integrality and safety evaluation but also investigation keystone in the material field.Based on the GM(1,1) model of the gray theory and the JC method of the traditional structure reliability analysis method , the remaining life analysis software and the plane frame structure displacement reliability calculation analysis programme on corroded pipelines were developed by using softwares of VB and MATLAB.Aiming at the VB/MATLAB interface issue in the forecasting software,the ActiveX automation technology was used to connect VB with MATLAB,so that the powerful function of MATLAB in image processing and numerical computation and the advantages of VB in the interface design call be integrated.With simple desks ,easy operation and through some examples, the results are proved sound and the program's veracity.The analysis method could provide a basis for the prediction of remaining life,the reliability analysis of complex construction and the inspection cycle of pipelines,and have feasibility and practicality.%腐蚀缺陷管道剩余寿命预测与结构可靠性计算问题不仅是管道完整性及安全性评价的重要组成部分还是材料界研究重点。该文以灰色理论GM(1,1)模型和传统计算结构可靠度的JC法为基础,使用VB和MATLAB开发腐蚀管道剩余寿命预测及结构可靠性分析计算程序,解决了两个计算程序的接口问题。使MATLAB在数值运算上的强大功能和VB在界面设计上的优势得以综合发挥。程序界面简单、操作方便快捷,且通过实例验证,计算结果较快,数据合理,程序编制准确无误,为腐蚀管道剩余寿命预测、复杂结构可靠性分析和腐蚀检测周期确定提供依据,具有可行性和实用性。

  8. 基于磨耗数据驱动模型的轮对镟修策略优化和剩余寿命预报%Optimization of the re-profiling strategy and remaining useful life prediction of wheels based on a data-driven wear model

    Institute of Scientific and Technical Information of China (English)

    王凌; 员华; 那文波; 陈锡爱; 李运堂

    2011-01-01

    Based on the wheel wear data of Guangzhou Metro, a new data-driven model of wheel wear is given in terms of the variationa of wheel diameter, flange thickness, and the re-profiling gain. A control limit policy for the wheel re-profiling decision is also proposed. According to the wheel wear model, the Monte Carlo simulation procedure of the re-profiling strategy is described in detail. Utilizing the Monte Carlo simulation, this wheel re-profiling strategy is optimized in order to minimize the expected long-run cost of wheel maintenance, and the prediction of remaining useful life of wheels is realized. The results indicate that wheels should be brought to 29-30mm when the flange is worn down to 27-27.5mm, which could reduce the expenditure associated with wheel re-profiling and extend the expected lifetime of wheels.The proposed prediction method of remaining useful life can derive the probability distribution of the remaining life of a wheel at a gven time.%基于广州地铁车辆轮对的磨耗实测数据,首先针对踏面直径和轮缘厚度两个型面参数以及镟修比例系数,给出了一种轮对磨耗的数据驱动模型.根据轮对应用要求,提出一种轮对镟修的控制限策略.在前述轮对磨耗模型的基础上,给出了该镟修策略的蒙特卡罗仿真步骤.然后应用蒙特卡罗仿真方法,实现以期望费用率最小为目标的轮对镟修策略优化,并给出轮对剩余寿命仿真预报.研究结果表明:当轮缘厚度减少到27 mm至27.5 mm时,通过镟修将轮缘厚度恢复到29mm至30mm,这样的镟修策略能降低轮对镟修期望费用率,并延长轮对期望使用寿命;提出的轮对剩余寿命仿真预报法能够给出某时刻轮对剩余寿命的概率密度分布.

  9. Comparisons of prediction models of quality of life after laparoscopic cholecystectomy: a longitudinal prospective study.

    Directory of Open Access Journals (Sweden)

    Hon-Yi Shi

    Full Text Available BACKGROUND: Few studies of laparoscopic cholecystectomy (LC outcome have used longitudinal data for more than two years. Moreover, no studies have considered group differences in factors other than outcome such as age and nonsurgical treatment. Additionally, almost all published articles agree that the essential issue of the internal validity (reproducibility of the artificial neural network (ANN, support vector machine (SVM, Gaussian process regression (GPR and multiple linear regression (MLR models has not been adequately addressed. This study proposed to validate the use of these models for predicting quality of life (QOL after LC and to compare the predictive capability of ANNs with that of SVM, GPR and MLR. METHODOLOGY/PRINCIPAL FINDINGS: A total of 400 LC patients completed the SF-36 and the Gastrointestinal Quality of Life Index at baseline and at 2 years postoperatively. The criteria for evaluating the accuracy of the system models were mean square error (MSE and mean absolute percentage error (MAPE. A global sensitivity analysis was also performed to assess the relative significance of input parameters in the system model and to rank the variables in order of importance. Compared to SVM, GPR and MLR models, the ANN model generally had smaller MSE and MAPE values in the training data set and test data set. Most ANN models had MAPE values ranging from 4.20% to 8.60%, and most had high prediction accuracy. The global sensitivity analysis also showed that preoperative functional status was the best parameter for predicting QOL after LC. CONCLUSIONS/SIGNIFICANCE: Compared with SVM, GPR and MLR models, the ANN model in this study was more accurate in predicting patient-reported QOL and had higher overall performance indices. Further studies of this model may consider the effect of a more detailed database that includes complications and clinical examination findings as well as more detailed outcome data.

  10. Ontology Based Feature Driven Development Life Cycle

    Directory of Open Access Journals (Sweden)

    Farheen Siddiqui

    2012-01-01

    Full Text Available The upcoming technology support for semantic web promises fresh directions for Software Engineering community. Also semantic web has its roots in knowledge engineering that provoke software engineers to look for application of ontology applications throughout the Software Engineering lifecycle. The internal components of a semantic web are "light weight", and may be of less quality standards than the externally visible modules. In fact the internal components are generated from external (ontological component. That's the reason agile development approaches such as feature driven development are suitable for applications internal component development. As yet there is no particular procedure that describes the role of ontology in FDD processes. Therefore we propose an ontology based feature driven development for semantic web application that can be used form application model development to feature design and implementation. Features are precisely defined in the OWL-based domain model. Transition from OWL based domain model to feature list is directly defined in transformation rules. On the other hand the ontology based overall model can be easily validated through automated tools. Advantages of ontology-based feature Driven development are also discussed.

  11. Development of accelerated test design for service-life prediction of solar array at Mead, Nebraska. Quarterly report

    Energy Technology Data Exchange (ETDEWEB)

    Gaines, G.B.; Thomas, R.E.; Noel, G.T.; Shilliday, T.S.; Wood, V.E.; Carmichael, D.C.

    1978-11-03

    As a significant beginning in applying accelerated tests to solar arrays for life-prediction purposes, this study is directed toward (a) developing a plan for predicting the service life of a specific solar array in a specific geographic site - viz., the 25-KW flat-plate array installed near Mead, Nebraska, and (b) developing technical information from laboratory and field measurements for designing an accelerated test that can be carried out in 2 years and have predictive validity for a service life as long as 20 years. Status of the program is described.

  12. Measurement Techniques and Instruments Suitable for Life-prediction Testing of Photovoltaic Arrays

    Science.gov (United States)

    Noel, G. T.; Wood, V. E.; Mcginniss, V. D.; Hassell, J. A.; Richard, N. A.; Gaines, G. B.; Carmichael, D. C.

    1979-01-01

    The validation of a 20-year service life for low-cost photovoltaic arrays is a critical requirement in the Low-Cost Solar Array (LSA) Project. The validation is accomplished through accelerated life-prediction tests. A two-phase study was conducted to address the needs before such tests are carried out. The results and recommended techniques from the Phase 1 investigation are summarized in the appendix. Phase 2 of the study is covered in this report and consisted of experimental evaluations of three techniques selected from these recommended as a results of the Phase 1 findings. The three techniques evaluated were specular and nonspecular optical reflectometry, chemiluminescence measurements, and electric current noise measurements.

  13. Computational Methodology for the Prediction of Functional Requirement Variations Across the Product Life-Cycle

    CERN Document Server

    Mandil, Guillaume; Rivière, Alain

    2009-01-01

    The great majority of engineered products are subject to thermo-mechanical loads which vary with the product environment during the various phases of its life-cycle (machining, assembly, intended service use...). Those load variations may result in different values of the parts nominal dimensions, which in turn generate corresponding variation of the effective clearance (functional requirement) in the assembly. Usually, and according to the contractual drawings, the parts are measured after the machining stage, whereas the interesting measurement values are the ones taken in service for they allow the prediction of clearance value under operating conditions. Unfortunately, measurement in operating conditions may not be practical to obtain. Hence, the main purpose of this research is to create, through computations and simulations, links between the values of the loads, dimensions and functional requirements during the successive phases of the life cycle of some given product. [...

  14. Predicting the natural mortality of marine fish from life history characteristics

    DEFF Research Database (Denmark)

    Gislason, Henrik

    the information necessary to estimate the scaling of natural mortality with size and asymptotic size. The estimated scaling is compared with output from multispecies fish stock models, with the empirical scaling of the maximum number of recruits per unit of spawning stock biomass with body size......For fish much of the life history is determined by body size. Body size and asymptotic size significantly influences important life history processes such as growth, maturity, egg production, and natural mortality. Futhermore, for a population to persist, offspring must be able to replace......, and with estimates from a comprehensive compilation of empirical data on the natural mortality of marine fishes. The comparisons are all in aggreement with the predictions from the model. We conclude that natural mortality scales with body length raised to a power around -1.6, with the asymptotic length...

  15. Neural Fuzzy Inference System-Based Weather Prediction Model and Its Precipitation Predicting Experiment

    Directory of Open Access Journals (Sweden)

    Jing Lu

    2014-11-01

    Full Text Available We propose a weather prediction model in this article based on neural network and fuzzy inference system (NFIS-WPM, and then apply it to predict daily fuzzy precipitation given meteorological premises for testing. The model consists of two parts: the first part is the “fuzzy rule-based neural network”, which simulates sequential relations among fuzzy sets using artificial neural network; and the second part is the “neural fuzzy inference system”, which is based on the first part, but could learn new fuzzy rules from the previous ones according to the algorithm we proposed. NFIS-WPM (High Pro and NFIS-WPM (Ave are improved versions of this model. It is well known that the need for accurate weather prediction is apparent when considering the benefits. However, the excessive pursuit of accuracy in weather prediction makes some of the “accurate” prediction results meaningless and the numerical prediction model is often complex and time-consuming. By adapting this novel model to a precipitation prediction problem, we make the predicted outcomes of precipitation more accurate and the prediction methods simpler than by using the complex numerical forecasting model that would occupy large computation resources, be time-consuming and which has a low predictive accuracy rate. Accordingly, we achieve more accurate predictive precipitation results than by using traditional artificial neural networks that have low predictive accuracy.

  16. 定向凝固镍基高温合金缺口低循环疲劳性能及寿命预测%Properties and Life Prediction of Low Cycle Fatigue Behavior on Notched DS Ni-based Superalloy

    Institute of Scientific and Technical Information of China (English)

    杨晓光; 黄佳; 王井科; 胡晓安; 石多奇

    2013-01-01

    Experimental investigation is carried out in this paper on the low cycle fatigue (LCF) behavior of directionally solidified (DS) Ni-based superalloy DZ125 at 850 ℃ with differential notch geometries and theoretical stress concentration factors (Kt).The stress-strain field at notch roots is obtained based on the elastic-plastic finite element analysis.Life prediction of notched specimens is then performed by the introduction of conventional and Kt-modified theory of critical distance (TCD) to SWT parameters.The results show that,the resistance of LCF has little to do with the geometrical shape of notch specimens but is heavily Kt-dependent.No matter by taking sharp specimens as calibration samples or dealing with critical distances by the statistical averaging method,both point method (PM) and line method (LM) of the conventional TCD exhibit that the life prediction ability related to the stress concentration factor is larger than the five times scatter band.However,ahighly improved scatter band within two times can be obtained by both point and line methods of Kt-modified TCD,and the two methods are notch-geometry independent.The SWT parameter may be used to consider the effect of mean stress (stress ratio).Therefore,accurate life prediction,based on the test data of LCF of smooth specimens and just one kind of notched specimens,can be carried out using this modified TCD for other notched specimens at different stress ratios,and its application will be simple and convenient.%针对定向凝固(DS)镍基高温合金DZ125开展了850℃条件下不同缺口形式和不同理论应力集中系数(Kt)下的低循环疲劳(LCF)试验研究.利用弹塑性有限元分析缺口根部的应力应变场,并将传统临界距离理论(TCD)及其Kt修正形式引入SWT参数,以此开展缺口试件LCF寿命预测研究.结果表明:高温LCF强度同缺口几何形状关联不大,但具有强的Kt相关性;无论是将尖锐缺口试件作为校

  17. Computing environmental life of electronic products based on failure physics

    Institute of Scientific and Technical Information of China (English)

    Yongqiang Zhang; Zongchang Xu; Chunyang Hu

    2016-01-01

    In some situations, the accelerated life test on en-vironmental stress for electronic products is not easily imple-mented due to various restrictions, and thus engineers are lacking of data of the product life test. Concerning this prob-lem, environmental life of the printed circuit board (PCB) board is calculated by way of physics of failure. Influences of thermal cycle and vibration on PCB and its components are studied. Based on the analysis of force and stress between components and the PCB board in thermal cycle events and vibration events, four life computing models of pins and sol-dered dots are established. The miler damage ratio is used to calculate the accumulated damage of a pin or a soldered dot, and then the environment life of the PCB board can be de-termined by the first failed one. Finaly, an example is used to ilustrate the models and their calculations.

  18. Creep fatigue life prediction for engine hot section materials (ISOTROPIC) fifth year progress review

    Science.gov (United States)

    Nelson, Richard S.; Harvey, Peter R.

    1987-01-01

    The need for advanced life prediction methods for hot section components for gas turbine engines is becoming more and more evident. The complex local strain and temperature histories at critical locations must be accurately interpreted to account for the effects of various damage mechanisms and their possible interactions. This program is designed to investigate these fundamental damage processes, identify modeling strategies, and develop practical models which can be used to guide the early design and development of new engines and to increase the durability of existing engines.

  19. Creep fatigue life prediction for engine hot section materials (isotropic): Fourth year progress review

    Science.gov (United States)

    Nelson, Richard S.; Schoendorf, John F.

    1986-01-01

    As gas turbine technology continues to advance, the need for advanced life prediction methods for hot section components is becoming more and more evident. The complex local strain and temperature histories at critical locations must be accurately interpreted to account for the effects of various damage mechanisms (such as fatigue, creep, and oxidation) and their possible interactions. As part of the overall NASA HOST effort, this program is designed to investigate these fundamental damage processes, identify modeling strategies, and develop practical models which can be used to guide the early design and development of new engines and to increase the durability of existing engines.

  20. Predictive visual tracking based on least absolute deviation estimation

    Institute of Scientific and Technical Information of China (English)

    Rongtai Cai; Yanjie Wang

    2008-01-01

    To cope with the occlusion and intersection between targets and the environment, location prediction is employed in the visual tracking system. Target trace is fitted by sliding subsection polynomials based on least absolute deviation (LAD) estimation, and the future location of target is predicted with the fitted trace. Experiment results show that the proposed location prediction algorithm based on LAD estimation has significant robustness advantages over least square (LS) estimation, and it is more effective than LS-based methods in visual tracking.

  1. Activity Prediction: A Twitter-based Exploration

    OpenAIRE

    Weerkamp, W.; Rijke, de, M.

    2012-01-01

    Social media platforms allow users to share their messages with everyone else. In microblogs, e.g., Twitter, people mostly report on what they did, they talk about current activities, and mention things they plan to do in the near future. In this paper, we propose the task of activity prediction, that is, trying to establish a set of activities that are likely to become popular at a later time. We perform a small-scale initial experiment, in which we try to predict popular activities for the ...

  2. Theoretical bases analysis of scientific prediction on marketing principles

    OpenAIRE

    A.S. Rosohata

    2012-01-01

    The article presents an overview categorical apparatus of scientific predictions and theoretical foundations results of scientific forecasting. They are integral part of effective management of economic activities. The approaches to the prediction of scientists in different fields of Social science and the categories modification of scientific prediction, based on principles of marketing are proposed.

  3. Theoretical bases analysis of scientific prediction on marketing principles

    Directory of Open Access Journals (Sweden)

    A.S. Rosohata

    2012-06-01

    Full Text Available The article presents an overview categorical apparatus of scientific predictions and theoretical foundations results of scientific forecasting. They are integral part of effective management of economic activities. The approaches to the prediction of scientists in different fields of Social science and the categories modification of scientific prediction, based on principles of marketing are proposed.

  4. Predicting Negative Life Outcomes from Early Aggressive-Disruptive Behavior Trajectories: Gender Differences in Maladaptation across Life Domains

    Science.gov (United States)

    Bradshaw, Catherine P.; Schaeffer, Cindy M.; Petras, Hanno; Ialongo, Nicholas

    2010-01-01

    Transactional theories of development suggest that displaying high levels of antisocial behavior early in life and persistently over time causes disruption in multiple life domains, which in turn places individuals at risk for negative life outcomes. We used longitudinal data from 1,137 primarily African American urban youth (49.1% female) to…

  5. Innovative Data Mining Based Approaches for Life Course Analysis

    OpenAIRE

    Ritschard, Gilbert; Gabadinho, Alexis; Mueller, Nicolas Séverin; Studer, Matthias

    2007-01-01

    This communication presents a just starting research project aiming at exploring the possibilities of resorting to data-mining-based methods in personal life course analysis. The project has also a socio-demographic goal, namely to gain new insights on how socio-demographic, familial, educational and professional events are entwined, on what are the characteristics of typical Swiss life trajectories and on changes in these characteristics over time. Methods for analyzing personal event histor...

  6. A BRB Based Fault Prediction Method of Complex Electromechanical Systems

    Directory of Open Access Journals (Sweden)

    Bangcheng Zhang

    2015-01-01

    Full Text Available Fault prediction is an effective and important approach to improve the reliability and reduce the risk of accidents for complex electromechanical systems. In order to use the quantitative information and qualitative knowledge efficiently to predict the fault, a new model is proposed on the basis of belief rule base (BRB. Moreover, an evidential reasoning (ER based optimal algorithm is developed to train the fault prediction model. The screw failure in computer numerical control (CNC milling machine servo system is taken as an example and the fault prediction results show that the proposed method can predict the behavior of the system accurately with combining qualitative knowledge and some quantitative information.

  7. Deterministic and Probabilistic Creep and Creep Rupture Enhancement to CARES/Creep: Multiaxial Creep Life Prediction of Ceramic Structures Using Continuum Damage Mechanics and the Finite Element Method

    Science.gov (United States)

    Jadaan, Osama M.; Powers, Lynn M.; Gyekenyesi, John P.

    1998-01-01

    High temperature and long duration applications of monolithic ceramics can place their failure mode in the creep rupture regime. A previous model advanced by the authors described a methodology by which the creep rupture life of a loaded component can be predicted. That model was based on the life fraction damage accumulation rule in association with the modified Monkman-Grant creep ripture criterion However, that model did not take into account the deteriorating state of the material due to creep damage (e.g., cavitation) as time elapsed. In addition, the material creep parameters used in that life prediction methodology, were based on uniaxial creep curves displaying primary and secondary creep behavior, with no tertiary regime. The objective of this paper is to present a creep life prediction methodology based on a modified form of the Kachanov-Rabotnov continuum damage mechanics (CDM) theory. In this theory, the uniaxial creep rate is described in terms of stress, temperature, time, and the current state of material damage. This scalar damage state parameter is basically an abstract measure of the current state of material damage due to creep deformation. The damage rate is assumed to vary with stress, temperature, time, and the current state of damage itself. Multiaxial creep and creep rupture formulations of the CDM approach are presented in this paper. Parameter estimation methodologies based on nonlinear regression analysis are also described for both, isothermal constant stress states and anisothermal variable stress conditions This creep life prediction methodology was preliminarily added to the integrated design code CARES/Creep (Ceramics Analysis and Reliability Evaluation of Structures/Creep), which is a postprocessor program to commercially available finite element analysis (FEA) packages. Two examples, showing comparisons between experimental and predicted creep lives of ceramic specimens, are used to demonstrate the viability of this methodology and

  8. Correlate Life Predictions and Condition Indicators in Helicopter Tail Gearbox Bearings

    Science.gov (United States)

    Dempsey, Paula J.; Bolander, Nathan; Haynes, Chris; Branning, Jeremy; Wade, Daniel R.

    2010-01-01

    Research to correlate bearing remaining useful life (RUL) predictions with Helicopter Health Usage Monitoring Systems (HUMS) condition indicators (CI) to indicate the damage state of a transmission component has been developed. Condition indicators were monitored and recorded on UH-60M (Black Hawk) tail gearbox output shaft thrust bearings, which had been removed from helicopters and installed in a bearing spall propagation test rig. Condition indicators monitoring the tail gearbox output shaft thrust bearings in UH-60M helicopters were also recorded from an on-board HUMS. The spal-lpropagation data collected in the test rig was used to generate condition indicators for bearing fault detection. A damage progression model was also developed from this data. Determining the RUL of this component in a helicopter requires the CI response to be mapped to the damage state. The data from helicopters and a test rig were analyzed to determine if bearing remaining useful life predictions could be correlated with HUMS condition indicators (CI). Results indicate data fusion analysis techniques can be used to map the CI response to the damage levels.

  9. Ultrasonic Sensing and Life Prediction for the DARPA Structural Integrity Prognosis System

    Science.gov (United States)

    Michaels, Jennifer E.; Michaels, Thomas E.; Cobb, Adam C.; Kacprzynski, Gregory J.

    2007-03-01

    The overall objective of the DARPA Structural Integrity Prognosis System (SIPS) program is to develop technologies to advance material damage state condition assessment with limited or no dedicated maintenance action. As a part of the sensors thrust area, an in situ ultrasonic sensing method was developed and demonstrated to detect cracks initiating from fastener holes and provide an estimate of total crack area. Crack area estimates were combined with load history data, projected future loads, and life prediction models to determine a probability density function for time-to-failure. The ultrasonic method utilizes two shear wave angle beam transducers operating in through transmission mode which are mounted on either side of the hole. The transmitted wave travels through the area of expected cracking, and the presence of cracks around the fastener holes decreases the amount of acoustic energy that is received. Furthermore, as cracks open and close during the fatigue process, the received energy is modulated, i.e., decreased when the cracks are open versus closed, and this non-linear behavior is the basis of algorithms developed to detect and size fastener holes cracks. The ultrasonic method was demonstrated as part of an integrated SIPS demonstration whereby aircraft-grade aluminum subcomponents were fatigued to failure. Results are presented from both the ultrasonic measurements and the integrated life prediction software.

  10. Fatigue Strength Prediction of Drilling Materials Based on the Maximum Non-metallic Inclusion Size

    Science.gov (United States)

    Zeng, Dezhi; Tian, Gang; Liu, Fei; Shi, Taihe; Zhang, Zhi; Hu, Junying; Liu, Wanying; Ouyang, Zhiying

    2015-12-01

    In this paper, the statistics of the size distribution of non-metallic inclusions in five drilling materials were performed. Based on the maximum non-metallic inclusion size, the fatigue strength of the drilling material was predicted. The sizes of non-metallic inclusions in drilling materials were observed to follow the inclusion size distribution rule. Then the maximum inclusion size in the fatigue specimens was deduced. According to the prediction equation of the maximum inclusion size and fatigue strength proposed by Murakami, fatigue strength of drilling materials was obtained. Moreover, fatigue strength was also measured through rotating bending tests. The predicted fatigue strength was significantly lower than the measured one. Therefore, according to the comparison results, the coefficients in the prediction equation were revised. The revised equation allowed the satisfactory prediction results of fatigue strength of drilling materials at the fatigue life of 107 rotations and could be used in the fast prediction of fatigue strength of drilling materials.

  11. Fatigue life prediction of magnetorheological elastomers subjected to dynamic equi-biaxial cyclic loading

    International Nuclear Information System (INIS)

    Prediction of fatigue life is of great significance in ensuring that dynamically loaded rubber components exhibit safety and reliability in service. In this text, the dynamic equi-biaxial fatigue behaviour of magnetorheological elastomer (MREs) using a bubble inflation method is described. Wöhler (S–N) curves for both isotropic and anisotropic MREs were produced by subjecting the compounds to cycling over a range of stress amplitudes (σa) between 0.75 MPa and 1.4 MPa. Changes in physical properties, including variation in stress–strain relations and complex modulus (E*) during the fatigue process were analysed. It was found that the complex modulus of MRE samples decreased throughout the entire fatigue test and failure took place at a limiting value of approximately 1.228MPa ± 4.38% for isotropic MREs and 1.295 ± 10.33% for anisotropic MREs. It was also determined that a dynamic stored energy criterion can be used as a plausible predictor in determining the fatigue life of MREs. - Highlights: • The first Wöhler curves for MREs subjected to equi-biaxial loading were presented. • Anisotropic MREs exhibited higher fatigue resistance than isotropic MREs. • There is a limiting value of complex modulus (E*) at which fatigue failure will occur. • The dynamic stored energy criterion can be used as a fatigue life predictor

  12. From First Life to Second Life: Evaluating Task-Based Language Learning in a New Environment

    Science.gov (United States)

    Jee, Min Jung

    2014-01-01

    With its growing number of users, Second Life as one of the avatar-based 3D virtual worlds has received attention from educators and researchers in various fields to explore its pedagogical benefits. Given the increasing implementation of technologies broadly in much instruction, this study investigated how ESL students negotiated meanings in…

  13. Predictive Models for Tomato Spotted Wilt Virus Spread Dynamics, Considering Frankliniella occidentalis Specific Life Processes as Influenced by the Virus.

    Science.gov (United States)

    Ogada, Pamella Akoth; Moualeu, Dany Pascal; Poehling, Hans-Michael

    2016-01-01

    Several models have been studied on predictive epidemics of arthropod vectored plant viruses in an attempt to bring understanding to the complex but specific relationship between the three cornered pathosystem (virus, vector and host plant), as well as their interactions with the environment. A large body of studies mainly focuses on weather based models as management tool for monitoring pests and diseases, with very few incorporating the contribution of vector's life processes in the disease dynamics, which is an essential aspect when mitigating virus incidences in a crop stand. In this study, we hypothesized that the multiplication and spread of tomato spotted wilt virus (TSWV) in a crop stand is strongly related to its influences on Frankliniella occidentalis preferential behavior and life expectancy. Model dynamics of important aspects in disease development within TSWV-F. occidentalis-host plant interactions were developed, focusing on F. occidentalis' life processes as influenced by TSWV. The results show that the influence of TSWV on F. occidentalis preferential behaviour leads to an estimated increase in relative acquisition rate of the virus, and up to 33% increase in transmission rate to healthy plants. Also, increased life expectancy; which relates to improved fitness, is dependent on the virus induced preferential behaviour, consequently promoting multiplication and spread of the virus in a crop stand. The development of vector-based models could further help in elucidating the role of tri-trophic interactions in agricultural disease systems. Use of the model to examine the components of the disease process could also boost our understanding on how specific epidemiological characteristics interact to cause diseases in crops. With this level of understanding we can efficiently develop more precise control strategies for the virus and the vector.

  14. Predictive Models for Tomato Spotted Wilt Virus Spread Dynamics, Considering Frankliniella occidentalis Specific Life Processes as Influenced by the Virus.

    Directory of Open Access Journals (Sweden)

    Pamella Akoth Ogada

    Full Text Available Several models have been studied on predictive epidemics of arthropod vectored plant viruses in an attempt to bring understanding to the complex but specific relationship between the three cornered pathosystem (virus, vector and host plant, as well as their interactions with the environment. A large body of studies mainly focuses on weather based models as management tool for monitoring pests and diseases, with very few incorporating the contribution of vector's life processes in the disease dynamics, which is an essential aspect when mitigating virus incidences in a crop stand. In this study, we hypothesized that the multiplication and spread of tomato spotted wilt virus (TSWV in a crop stand is strongly related to its influences on Frankliniella occidentalis preferential behavior and life expectancy. Model dynamics of important aspects in disease development within TSWV-F. occidentalis-host plant interactions were developed, focusing on F. occidentalis' life processes as influenced by TSWV. The results show that the influence of TSWV on F. occidentalis preferential behaviour leads to an estimated increase in relative acquisition rate of the virus, and up to 33% increase in transmission rate to healthy plants. Also, increased life expectancy; which relates to improved fitness, is dependent on the virus induced preferential behaviour, consequently promoting multiplication and spread of the virus in a crop stand. The development of vector-based models could further help in elucidating the role of tri-trophic interactions in agricultural disease systems. Use of the model to examine the components of the disease process could also boost our understanding on how specific epidemiological characteristics interact to cause diseases in crops. With this level of understanding we can efficiently develop more precise control strategies for the virus and the vector.

  15. Feature Selection for Neural Network Based Stock Prediction

    Science.gov (United States)

    Sugunnasil, Prompong; Somhom, Samerkae

    We propose a new methodology of feature selection for stock movement prediction. The methodology is based upon finding those features which minimize the correlation relation function. We first produce all the combination of feature and evaluate each of them by using our evaluate function. We search through the generated set with hill climbing approach. The self-organizing map based stock prediction model is utilized as the prediction method. We conduct the experiment on data sets of the Microsoft Corporation, General Electric Co. and Ford Motor Co. The results show that our feature selection method can improve the efficiency of the neural network based stock prediction.

  16. Bayesian probabilistic model for life prediction and fault mode classification of solid state luminaires

    Energy Technology Data Exchange (ETDEWEB)

    Lall, Pradeep [Auburn Univ., Auburn, AL (United States); Wei, Junchao [Auburn Univ., Auburn, AL (United States); Sakalaukus, Peter [Auburn Univ., Auburn, AL (United States)

    2014-06-22

    A new method has been developed for assessment of the onset of degradation in solid state luminaires to classify failure mechanisms by using metrics beyond lumen degradation that are currently used for identification of failure. Luminous Flux output, Correlated Color Temperature Data on Philips LED Lamps has been gathered under 85°C/85%RH till lamp failure. Failure modes of the test population of the lamps have been studied to understand the failure mechanisms in 85°C/85%RH accelerated test. Results indicate that the dominant failure mechanism is the discoloration of the LED encapsulant inside the lamps which is the likely cause for the luminous flux degradation and the color shift. The acquired data has been used in conjunction with Bayesian Probabilistic Models to identify luminaires with onset of degradation much prior to failure through identification of decision boundaries between lamps with accrued damage and lamps beyond the failure threshold in the feature space. In addition luminaires with different failure modes have been classified separately from healthy pristine luminaires. The α-λ plots have been used to evaluate the robustness of the proposed methodology. Results show that the predicted degradation for the lamps tracks the true degradation observed during 85°C/85%RH during accelerated life test fairly closely within the ±20% confidence bounds. Correlation of model prediction with experimental results indicates that the presented methodology allows the early identification of the onset of failure much prior to development of complete failure distributions and can be used for assessing the damage state of SSLs in fairly large deployments. It is expected that, the new prediction technique will allow the development of failure distributions without testing till L70 life for the manifestation of failure.

  17. Fatigue life prediction of casing welded pipes by using the extended finite element method

    Directory of Open Access Journals (Sweden)

    Ljubica Lazić Vulićević

    2016-03-01

    Full Text Available The extended finite element (XFEM method has been used to simulate fatigue crack growth in casing pipe, made of API J55 steel by high-frequency welding, in order estimate its structural integrity and life. Based on the critical value of stress intensity factor KIc, measured in different regions of welded joint, the crack was located in the base metal as the region with the lowest resistance to crack initiation and propagation. The XFEM was first applied to the 3 point bending specimens to verify numerical results with the experimental ones. After successful verification, the XFEM was used to simulate fatigue crack growth, position axially in the pipe, and estimate its remaining life.

  18. Link prediction based on path entropy

    CERN Document Server

    Xu, Zhongqi; Yang, Jian

    2015-01-01

    Information theory has been taken as a prospective tool for quantifying the complexity of complex networks. In this paper, we first study the information entropy or uncertainty of a path using the information theory. Then we apply the path entropy to the link prediction problem in real-world networks. Specifically, we propose a new similarity index, namely Path Entropy (PE) index, which considers the information entropies of shortest paths between node pairs with penalization to long paths. Empirical experiments demonstrate that PE index outperforms the mainstream link predictors.

  19. Nondestructive control of condition and prediction of cable life time at nuclear power plants

    International Nuclear Information System (INIS)

    The most effective methods for nondestructive control of a cable condition, which are used for a periodic assessment of expected life of power and control cables at nuclear power plants of Rosenergoatom Concern OJSC, are presented. In spite of the fact that many methods are based on physical principles that are well-known for a long time, they have been improved due to the experimental data received lately. (author)

  20. Robustness of Prediction Based Delay Compensation for Nonlinear Systems

    CERN Document Server

    Findeisen, Rolf; Pannek, Jürgen; Varutti, Paolo

    2011-01-01

    Control of systems where the information between the controller, actuator, and sensor can be lost or delayed can be challenging with respect to stability and performance. One way to overcome the resulting problems is the use of prediction based compensation schemes. Instead of a single input, a sequence of (predicted) future controls is submitted and implemented at the actuator. If suitable, so-called prediction consistent compensation and control schemes, such as certain predictive control approaches, are used, stability of the closed loop in the presence of delays and packet losses can be guaranteed. In this paper, we show that control schemes employing prediction based delay compensation approaches do posses inherent robustness properties. Specifically, if the nominal closed loop system without delay compensation is ISS with respect to perturbation and measurement errors, then the closed loop system employing prediction based delay compensation techniques is robustly stable. We analyze the influence of the...

  1. Metabotypes with properly functioning mitochondria and anti-inflammation predict extended productive life span in dairy cows.

    Science.gov (United States)

    Huber, K; Dänicke, S; Rehage, J; Sauerwein, H; Otto, W; Rolle-Kampczyk, U; von Bergen, M

    2016-01-01

    The failure to adapt metabolism to the homeorhetic demands of lactation is considered as a main factor in reducing the productive life span of dairy cows. The so far defined markers of production performance and metabolic health in dairy cows do not predict the length of productive life span satisfyingly. This study aimed to identify novel pathways and biomarkers related to productive life in dairy cows by means of (targeted) metabolomics. In a longitudinal study from 42 days before up to 100 days after parturition, we identified metabolites such as long-chain acylcarnitines and biogenic amines associated with extended productive life spans. These metabolites are mainly secreted by the liver and depend on the functionality of hepatic mitochondria. The concentrations of biogenic amines and some acylcarnitines differed already before the onset of lactation thus indicating their predictive potential for continuation or early ending of productive life. PMID:27089826

  2. A Model of the Fatigue Life Distribution of Composite Laminates Based on Their Static Strength Distribution

    Institute of Scientific and Technical Information of China (English)

    Wu Fuqiang; Yao Weixing

    2008-01-01

    The reasons of the static strength dispersion and the fatigue life dispersion of composite laminates are analyzed in this article.It is concluded that the inner original defects,which derived from the manufacturing process of composite laminates,are the common and major reason of causing the random distributions of the static strength and the fatigue life.And there is a correlative relation between the two distributions.With the study of statistical relationship between the fatigue loading and the fatigue life in the uniform confidence level and the same survival rate S-N curves of material,the relationship between the static strength distribution and the fatigue life distribution through a material S-N curve model has been obtained.And then the model which is used to describe the distributions of fatigue life of composites,based on their distributions of static strength,is set up.This model reasonably reflects the effects of the inner original defects on the static strength dispersion and on the fatigue life dispersion of composite laminates.The experimental data of three kinds of composite laminates are employed to verify this model,and the results show that this model can predict the random distributions of fatigue life for composites under any fatigue loads fairly well.

  3. Fatigue life prediction and experiment research for composite laminates with circular hole

    Institute of Scientific and Technical Information of China (English)

    齐红宇; 温卫东; 孙联文

    2004-01-01

    Based on the fatigue prediction model of exponential function and Whitney-Nuismer(WN) criterion of static strength for the composite material laminate with a circular hole, the stress correct factor (β) was put forward and a new fatigue prediction model for composite material laminate was set up. T300/KH304, which is recently studied and is a high capability composite material, was used as the raw material. In order to gain the factorβ, the fatigue experiments of the laminates with holes in different diameters and the same ratio of width to diameter were conducted. The fatigue analysis and tests of the laminates with a hole 5 mm in diameter are carried out at different stress levels, and the results meet the engineering requirement. The simple, prompt and practical method is provided for the prediction of S-N curve of composite laminate with a circular hole.

  4. Sleep quality predicts quality of life in chronic obstructive pulmonary disease

    Directory of Open Access Journals (Sweden)

    Tzahit Simon-Tuval

    2010-12-01

    Full Text Available Steven M Scharf1*, Nimrod Maimon2*, Tzahit Simon-Tuval3, Barbara J Bernhard-Scharf4, Haim Reuveni2, Ariel Tarasiuk21Department of Pulmonary and Critical Care, University of Maryland, Baltimore, MD, USA; 2Faculty of Health Sciences, Ben-Gurion University, Beersheba, Israel; 3Guilford Glazer School of Business and Management, Ben Gurion University, Beersheba, Israel; 4Mt. Washington Pediatric Hospital, Baltimore, MD, USA; The study was performed at the Soroka University Medical Center, Beer Sheva, Israel*Drs Scharf and Maimon contributed equally to this manuscript.Purpose: Chronic obstructive pulmonary disease (COPD patients may suffer from poor sleep and health-related quality of life. We hypothesized that disturbed sleep in COPD is correlated with quality of life.Methods: In 180 patients with COPD (forced expired volume in 1 second [FEV1] 47.6 ± 15.2% predicted, 77.8% male, aged 65.9 ± 11.7 years, we administered general (Health Utilities Index 3 and disease-specific (St George’s Respiratory questionnaires and an index of disturbed sleep (Pittsburgh Sleep Quality Index.Results: Overall scores indicated poor general (Health Utilities Index 3: 0.52 ± 0.38, disease-specific (St George’s: 57.0 ± 21.3 quality of life and poor sleep quality (Pittsburgh 11.0 ± 5.4. Sleep time correlated with the number of respiratory and anxiety symptoms reported at night. Seventy-seven percent of the patients had Pittsburg scores >5, and the median Pittsburgh score was 12. On multivariate regression, the Pittsburgh Sleep Quality Index was an independent predictor of both the Health Utilities Index 3 and the St George’s scores, accounting for 3% and 5%, respectively, of the scores. Only approximately 25% of the patients demonstrated excessive sleepiness (Epworth Sleepiness Scale >9.Conclusions: Most patients with COPD suffer disturbed sleep. Sleep quality was correlated with general and disease-specific quality of life. Only a minority of COPD patients

  5. Fabrication and Life Prediction of SSiC Ceramic Joint Joined with Silicon Resin YR3370

    Institute of Scientific and Technical Information of China (English)

    YUAN Xiao-kun; XU Bing-she

    2007-01-01

    Joints between sintered silicon carbide (SSiC) were produced using a polysiloxane silicon resin YR3370 (GE Toshiba Silicones) as joining material. Samples were heat treated in a 99.99% nitrogen flux at temperatures ranging from 1 100 ℃ to 1 300 ℃. Three point bending strength of the joint reached the maximum of 179 MPa as joined at 1 200 ℃. The joining layer is continuous, homogeneous and densified and has a thickness of 2 tm -5 μm. The joining mechanism is that the amorphous silicon oxycarbide (SixOyCz) ceramic pyrolyzed from silicon resin YR3370 acts as an inorganic adhesive to SSiC substrate, which means the formation of the continuous Si-C bond structure between SixOyCz structure and SSiC substrate. Life prediction of the ceramic joint can be realized through the measurement of the critical time of the joint after the cyclic loading test.

  6. Development and Life Prediction of Erosion Resistant Turbine Low Conductivity Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

    2010-01-01

    Future rotorcraft propulsion systems are required to operate under highly-loaded conditions and in harsh sand erosion environments, thereby imposing significant material design and durability issues. The incorporation of advanced thermal barrier coatings (TBC) in high pressure turbine systems enables engine designs with higher inlet temperatures, thus improving the engine efficiency, power density and reliability. The impact and erosion resistance of turbine thermal barrier coating systems are crucial to the turbine coating technology application, because a robust turbine blade TBC system is a prerequisite for fully utilizing the potential coating technology benefit in the rotorcraft propulsion. This paper describes the turbine blade TBC development in addressing the coating impact and erosion resistance. Advanced thermal barrier coating systems with improved performance have also been validated in laboratory simulated engine erosion and/or thermal gradient environments. A preliminary life prediction modeling approach to emphasize the turbine blade coating erosion is also presented.

  7. Response Surface Approximation for Fatigue Life Prediction and Its Application to Multi-Criteria Optimization With a Priori Preference Information

    International Nuclear Information System (INIS)

    In this paper, a versatile multi-criteria optimization concept for fatigue life prediction is introduced. Multi-criteria decision making in engineering design refers to obtaining a preferred optimal solution in the context of conflicting design objectives. Compromise decision support problems are used to model engineering decisions involving multiple trade-offs. These methods typically rely on a summation of weighted attributes to accomplish trade-offs among competing objectives. This paper gives an interpretation of the decision parameters as governing both the relative importance of the attributes and the degree of compensation between them. The approach utilizes a response surface model, the compromise decision support problem, which is a multi-objective formulation based on goal programming. Examples illustrate the concepts and demonstrate their applicability

  8. Science gateways for semantic-web-based life science applications.

    Science.gov (United States)

    Ardizzone, Valeria; Bruno, Riccardo; Calanducci, Antonio; Carrubba, Carla; Fargetta, Marco; Ingrà, Elisa; Inserra, Giuseppina; La Rocca, Giuseppe; Monforte, Salvatore; Pistagna, Fabrizio; Ricceri, Rita; Rotondo, Riccardo; Scardaci, Diego; Barbera, Roberto

    2012-01-01

    In this paper we present the architecture of a framework for building Science Gateways supporting official standards both for user authentication and authorization and for middleware-independent job and data management. Two use cases of the customization of the Science Gateway framework for Semantic-Web-based life science applications are also described.

  9. Model Based Predictive Control of a Fully Parallel Robot

    OpenAIRE

    Vivas, Oscar Andrès; Poignet, Philippe

    2003-01-01

    This paper deals with an efficient application of a model based predictive control in parallel machines. A receding horizon control strategy based on a simplified dynamic model is implemented. Experimental results are shown for the H4 robot, a fully parallel structure providing 3 degrees of freedom (dof) in translation and 1 dof in rotation. The model based predictive control and the commonly used computed torque control strategies are compared. The tracking performances and the robustness wi...

  10. Copula-based prediction of economic movements

    Science.gov (United States)

    García, J. E.; González-López, V. A.; Hirsh, I. D.

    2016-06-01

    In this paper we model the discretized returns of two paired time series BM&FBOVESPA Dividend Index and BM&FBOVESPA Public Utilities Index using multivariate Markov models. The discretization corresponds to three categories, high losses, high profits and the complementary periods of the series. In technical terms, the maximal memory that can be considered for a Markov model, can be derived from the size of the alphabet and dataset. The number of parameters needed to specify a discrete multivariate Markov chain grows exponentially with the order and dimension of the chain. In this case the size of the database is not large enough for a consistent estimation of the model. We apply a strategy to estimate a multivariate process with an order greater than the order achieved using standard procedures. The new strategy consist on obtaining a partition of the state space which is constructed from a combination, of the partitions corresponding to the two marginal processes and the partition corresponding to the multivariate Markov chain. In order to estimate the transition probabilities, all the partitions are linked using a copula. In our application this strategy provides a significant improvement in the movement predictions.

  11. Satellite Lithium-Ion Battery Remaining Cycle Life Prediction with Novel Indirect Health Indicator Extraction

    Directory of Open Access Journals (Sweden)

    Haitao Liao

    2013-07-01

    Full Text Available Prognostics and remaining useful life (RUL estimation for lithium-ion batteries play an important role in intelligent battery management systems (BMS. The capacity is often used as the fade indicator for estimating the remaining cycle life of a lithium-ion battery. For spacecraft requiring high reliability and long lifetime, in-orbit RUL estimation and reliability verification on ground should be carefully addressed. However, it is quite challenging to monitor and estimate the capacity of a lithium-ion battery on-line in satellite applications. In this work, a novel health indicator (HI is extracted from the operating parameters of a lithium-ion battery to quantify battery degradation. Moreover, the Grey Correlation Analysis (GCA is utilized to evaluate the similarities between the extracted HI and the battery’s capacity. The result illustrates the effectiveness of using this new HI for fading indication. Furthermore, we propose an optimized ensemble monotonic echo state networks (En_MONESN algorithm, in which the monotonic constraint is introduced to improve the adaptivity of degradation trend estimation, and ensemble learning is integrated to achieve high stability and precision of RUL prediction. Experiments with actual testing data show the efficiency of our proposed method in RUL estimation and degradation modeling for the satellite lithium-ion battery application.

  12. Learning impairments identified early in life are predictive of future impairments associated with aging

    Science.gov (United States)

    Hullinger, Rikki; Burger, Corinna

    2016-01-01

    The Morris water maze (MWM) behavioral paradigm is commonly used to measure spatial learning and memory in rodents. It is widely accepted that performance in the MWM declines with age. However, young rats ubiquitously perform very well on established versions of the water maze, suggesting that more challenging tasks may be required to reveal subtle differences in young animals. Therefore, we have used a one-day water maze and novel object recognition to test whether more sensitive paradigms of memory in young animals could identify subtle cognitive impairments early in life that might become accentuated later with senescence. We have found that these two tasks reliably separate young rats into inferior and superior learners, are highly correlated, and that performance on these tasks early in life is predictive of performance at 12 months of age. Furthermore, we have found that repeated training in this task selectively improves the performance of inferior learners, suggesting that behavioral training from an early age may provide a buffer against age-related cognitive decline. PMID:26283528

  13. Safety Prediction Analysis of the Agricultural Products Processing Based on the BP Neural Network

    Directory of Open Access Journals (Sweden)

    Jing Li

    2015-09-01

    Full Text Available By using BP neural network algorithm, this study aims at prompting the accuracy of safety prediction of the agriculture products processing. The science prediction of the deep-frozen dumplings' shelf-life has an important guiding significance for human health and the safety of quick-frozen food. Artificial Neural Network (ANN is a kind of information processing system which is established by simulating the human nervous system. Based on these, by using the effective theory of integrated temperature combined with BP neural network method to predict the shelf-life of the frozen dumplings in this study, we aim at providing a theory basis for monitoring and controlling the quality change in the storage process of deep-frozen dumplings’ temperature fluctuations. Finally, an example is given to show that it is very effective by using the method adopted in this study.

  14. A Methodology to Predict Uniform Material Fatigue Life of Cast Iron: Law for Cast Iron%A Methodology to Predict Uniform Material Fatigue Life of Cast Iron: Law for Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Sinan Korkmaz

    2011-01-01

    Mechanical, physical and manufacturing properties of east iron make it attractive for many fields of application, such as cranks and cylinder holds. As in design of all metals, fatigue life prediction is an intrinsic part of the design process of structural sections that are made of cast iron. A methodology to predict high-cycle fatigue life of cast iron is proposed. Stress amplitude-strain amplitude, strain amplitude-number of loading cycles relationships of cast iron are investigated. Also, fatigue life prediction in terms of Smith, Watson and Topper parameter is carried out using the proposed method. Results indicate that the analytical outcomes of the proposed methodology are in good accordance with the experimental data for the two studied types of cast iron: EN-GJS-400 and EN-GJS-600.

  15. Online Forums Hotspot Prediction Based on Sentiment Analysis

    OpenAIRE

    V. Murali Bhaskarn; K. Nirmala Devi

    2012-01-01

    Problem statement: Online forums hotspot prediction is one of the significant research areas in web mining, which can help people make proper decision in daily life. Online forums, news reports and blogs, are containing large volume of public opinion information. Rapid growth of network arouses much attention on public opinion, it is important to analyse the public opinion in time and understands the trends of their opinion correctly. Approach: The sentiment analysis and text mining are impor...

  16. Lasso based feature selection for malaria risk exposure prediction

    OpenAIRE

    Kouwayè, Bienvenue; Fonton, Noël; Rossi, Fabrice

    2015-01-01

    In life sciences, the experts generally use empirical knowledge to recode variables, choose interactions and perform selection by classical approach. The aim of this work is to perform automatic learning algorithm for variables selection which can lead to know if experts can be help in they decision or simply replaced by the machine and improve they knowledge and results. The Lasso method can detect the optimal subset of variables for estimation and prediction under some conditions. In this p...

  17. Size-based predictions of food web patterns

    DEFF Research Database (Denmark)

    Zhang, Lai; Hartvig, Martin; Knudsen, Kim;

    2014-01-01

    simulations with varying species richness. To this end, we develop a new size- and trait-based food web model that can be simplified into an analytically solvable size-based model. We confirm existing solutions for the size distribution and derive novel predictions for maximum trophic level and invasion...... of species are continuously distributed on a size-trait axis. It is, however, an open question whether such predictions are valid for a food web with a finite number of species embedded in a network structure. We address this question by comparing the size-based predictions to results from dynamic food web...... resistance. Our results show that the predicted size-spectrum exponent is borne out in the simulated food webs even with few species, albeit with a systematic bias. The predicted maximum trophic level turns out to be an upper limit since simulated food webs may have a lower number of trophic levels...

  18. Quality and shelf-life prediction for retail fresh hake (Merluccius merluccius).

    Science.gov (United States)

    García, Míriam R; Vilas, Carlos; Herrera, Juan R; Bernárdez, Marta; Balsa-Canto, Eva; Alonso, Antonio A

    2015-09-01

    Fish quality has a direct impact on market price and its accurate assessment and prediction are of main importance to set prices, increase competitiveness, resolve conflicts of interest and prevent food wastage due to conservative product shelf-life estimations. In this work we present a general methodology to derive predictive models of fish freshness under different storage conditions. The approach makes use of the theory of optimal experimental design, to maximize data information and in this way reduce the number of experiments. The resulting growth model for specific spoilage microorganisms in hake (Merluccius merluccius) is sufficiently informative to estimate quality sensory indexes under time-varying temperature profiles. In addition it incorporates quantitative information of the uncertainty induced by fish variability. The model has been employed to test the effect of factors such as fishing gear or evisceration, on fish spoilage and therefore fish quality. Results show no significant differences in terms of microbial growth between hake fished by long-line or bottom-set nets, within the implicit uncertainty of the model. Similar conclusions can be drawn for gutted and un-gutted hake along the experiment horizon. In addition, whenever there is the possibility to carry out the necessary experiments, this approach is sufficiently general to be used in other fish species and under different stress variables.

  19. Quality and shelf-life prediction for retail fresh hake (Merluccius merluccius).

    Science.gov (United States)

    García, Míriam R; Vilas, Carlos; Herrera, Juan R; Bernárdez, Marta; Balsa-Canto, Eva; Alonso, Antonio A

    2015-09-01

    Fish quality has a direct impact on market price and its accurate assessment and prediction are of main importance to set prices, increase competitiveness, resolve conflicts of interest and prevent food wastage due to conservative product shelf-life estimations. In this work we present a general methodology to derive predictive models of fish freshness under different storage conditions. The approach makes use of the theory of optimal experimental design, to maximize data information and in this way reduce the number of experiments. The resulting growth model for specific spoilage microorganisms in hake (Merluccius merluccius) is sufficiently informative to estimate quality sensory indexes under time-varying temperature profiles. In addition it incorporates quantitative information of the uncertainty induced by fish variability. The model has been employed to test the effect of factors such as fishing gear or evisceration, on fish spoilage and therefore fish quality. Results show no significant differences in terms of microbial growth between hake fished by long-line or bottom-set nets, within the implicit uncertainty of the model. Similar conclusions can be drawn for gutted and un-gutted hake along the experiment horizon. In addition, whenever there is the possibility to carry out the necessary experiments, this approach is sufficiently general to be used in other fish species and under different stress variables. PMID:26058006

  20. A 3.5 year diary study: Remembering and life story importance are predicted by different event characteristics.

    Science.gov (United States)

    Thomsen, Dorthe Kirkegaard; Jensen, Thomas; Holm, Tine; Olesen, Martin Hammershøj; Schnieber, Anette; Tønnesvang, Jan

    2015-11-01

    Forty-five participants described and rated two events each week during their first term at university. After 3.5 years, we examined whether event characteristics rated in the diary predicted remembering, reliving, and life story importance at the follow-up. In addition, we examined whether ratings of life story importance were consistent across a three year interval. Approximately 60% of events were remembered, but only 20% of these were considered above medium importance to life stories. Higher unusualness, rehearsal, and planning predicted whether an event was remembered 3.5 years later. Higher goal-relevance, importance, emotional intensity, and planning predicted life story importance 3.5 years later. There was a moderate correlation between life story importance rated three months after the diary and rated at the 3.5 year follow-up. The results suggest that autobiographical memory and life stories are governed by different mechanisms and that life story memories are characterized by some degree of stability.

  1. Model Predictive Control based on Finite Impulse Response Models

    DEFF Research Database (Denmark)

    Prasath, Guru; Jørgensen, John Bagterp

    2008-01-01

    We develop a regularized l2 finite impulse response (FIR) predictive controller with input and input-rate constraints. Feedback is based on a simple constant output disturbance filter. The performance of the predictive controller in the face of plant-model mismatch is investigated by simulations ...

  2. Exact Amplitude--Based Resummation QCD Predictions and LHC Data

    CERN Document Server

    Ward, B F L; Yost, S A

    2014-01-01

    We present the current status of the comparisons with the respective data of the predictions of our approach of exact amplitude-based resummation in quantum field theory as applied to precision QCD calculations as needed for LHC physics, using the MC Herwiri1.031. The agreement between the theoretical predictions and the data exhibited continues to be encouraging.

  3. Research on Life Signals Detection Based on Higher Order Statistics

    Directory of Open Access Journals (Sweden)

    Jian-Jun Li

    2012-10-01

    Full Text Available The life signals are built on harmonic mode for their low frequency, quasi-periodicity, low SNR, and the easy submerged in strong clutter noise. The method for detecting life signal based on adaptive filter and high order statistics is presented, in which neither the Gaussian supposition of the observed signal, nor a prior information about the waveform and arrival time of the observed signal is necessary. The principle of method is to  separate the spectrum of input signal into many narrow frequency bands, whose Sub-band signal  is followed by a short-time estimation of higher-order statistics so as to suppress Gaussian noises. Simulated results show that the method can effectively detect life signals from noise with good convergence speed and stability, and greatly improve the signal quality with respect to LMS method.

  4. Slope Deformation Prediction Based on Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Lei JIA

    2013-07-01

    Full Text Available This paper principally studies the prediction of slope deformation based on Support Vector Machine (SVM. In the prediction process,explore how to reconstruct the phase space. The geological body’s displacement data obtained from chaotic time series are used as SVM’s training samples. Slope displacement caused by multivariable coupling is predicted by means of single variable. Results show that this model is of high fitting accuracy and generalization, and provides reference for deformation prediction in slope engineering.

  5. Entropy-based link prediction in weighted networks

    CERN Document Server

    Xu, Zhongqi; Sharafat, Rajput Ramiz; Li, Lunbo; Yang, Jian

    2016-01-01

    Information entropy has been proved to be an effective tool to quantify the structural importance of complex networks. In the previous work (Xu et al, 2016 \\cite{xu2016}), we measure the contribution of a path in link prediction with information entropy. In this paper, we further quantify the contribution of a path with both path entropy and path weight, and propose a weighted prediction index based on the contributions of paths, namely Weighted Path Entropy (WPE), to improve the prediction accuracy in weighted networks. Empirical experiments on six weighted real-world networks show that WPE achieves higher prediction accuracy than three typical weighted indices.

  6. Protein-Based Urine Test Predicts Kidney Transplant Outcomes

    Science.gov (United States)

    ... News Releases News Release Thursday, August 22, 2013 Protein-based urine test predicts kidney transplant outcomes NIH- ... supporting development of noninvasive tests. Levels of a protein in the urine of kidney transplant recipients can ...

  7. Prediction-based estimating functions: Review and new developments

    DEFF Research Database (Denmark)

    Sørensen, Michael

    2011-01-01

    The general theory of prediction-based estimating functions for stochastic process models is reviewed and extended. Particular attention is given to optimal estimation, asymptotic theory and Gaussian processes. Several examples of applications are presented. In particular, partial observation...

  8. Evaluating the real-world predictive validity of the Body Image Quality of Life Inventory using Ecological Momentary Assessment.

    Science.gov (United States)

    Heron, Kristin E; Mason, Tyler B; Sutton, Tiphanie G; Myers, Taryn A

    2015-09-01

    Perceptions of physical appearance, or body image, can affect psychosocial functioning and quality of life (QOL). The present study evaluated the real-world predictive validity of the Body Image Quality of Life Inventory (BIQLI) using Ecological Momentary Assessment (EMA). College women reporting subclinical disordered eating/body dissatisfaction (N=131) completed the BIQLI and related measures. For one week they then completed five daily EMA surveys of mood, social interactions, stress, and eating behaviors on palmtop computers. Results showed better body image QOL was associated with less negative affect, less overwhelming emotions, more positive affect, more pleasant social interactions, and higher self-efficacy for handling stress. Lower body image QOL was marginally related to less overeating and lower loss of control over eating in daily life. To our knowledge, this is the first study to support the real-world predictive validity of the BIQLI by identifying social, affective, and behavioral correlates in everyday life using EMA. PMID:26302376

  9. Influence of sulphates on chloride diffusion and the effect of this on service life prediction of concrete in a submerged marine environment

    OpenAIRE

    Maes, M; Caspeele, R.; Van den Heede, P.; De Belie, N.

    2012-01-01

    Single-ion attack by chlorides and multi-ion attack by chlorides and sulphates were compared with respect to the full probabilistic service life prediction of concrete structures, according to fib Bulletin 34. Especially the influence of sulphates on the chloride diffusion coefficient was investigated more thoroughly. Four concrete mixtures were tested, two Portland cement concretes and two blast-furnace slag concretes. Migration tests and natural diffusion tests were executed, based on NT bu...

  10. CLINICAL DATABASE ANALYSIS USING DMDT BASED PREDICTIVE MODELLING

    Directory of Open Access Journals (Sweden)

    Srilakshmi Indrasenan

    2013-04-01

    Full Text Available In recent years, predictive data mining techniques play a vital role in the field of medical informatics. These techniques help the medical practitioners in predicting various classes which is useful in prediction treatment. One of such major difficulty is prediction of survival rate in breast cancer patients. Breast cancer is a common disease these days and fighting against it is a tough battle for both the surgeons and the patients. To predict the survivability rate in breast cancer patients which helps the medical practitioner to select the type of treatment a predictive data mining technique called Diversified Multiple Decision Tree (DMDT classification is used. Additionally, to avoid difficulties from the outlier and skewed data, it is also proposed to perform the improvement of training space by outlier filtering and over sampling. As a result, this novel approach gives the survivability rate of the cancer patients based on which the medical practitioners can choose the type of treatment.

  11. Local-prediction-based difference expansion reversible watermarking.

    Science.gov (United States)

    Dragoi, Ioan-Catalin; Coltuc, Dinu

    2014-04-01

    This paper investigates the use of local prediction in difference expansion reversible watermarking. For each pixel, a least square predictor is computed on a square block centered on the pixel and the corresponding prediction error is expanded. The same predictor is recovered at detection without any additional information. The proposed local prediction is general and it applies regardless of the predictor order or the prediction context. For the particular cases of least square predictors with the same context as the median edge detector, gradient-adjusted predictor or the simple rhombus neighborhood, the local prediction-based reversible watermarking clearly outperforms the state-of-the-art schemes based on the classical counterparts. Experimental results are provided.

  12. The probabilistic prediction of NPP equipment life time under erosion-corrosion wear conditions

    International Nuclear Information System (INIS)

    There is considered the method of the non-failure probability (NFP) estimation for the NNP equipment subjected to erosion-corrosion wear (ECW). The break process under conditions of ECW consists of two stages is supposed. The first stage is erosion-corrosion friability (ECF) stage connected with surface friability without of erosion-corrosion products carrying out, and the second-erosion-.corrosion wear (ECW) stage, being accompanied by wall thickness decrease. The first stage time (incubation) estimation is based on damage summation from the blow action of water drops in steam-water flow. The method is based on the Central Limit Theorem applied to the sum of the micro damages from the water drops blow action. Expectation and dispersion formulas for the micro damages are obtained. The EC method also takes into account the possible defects presence in tube material. The incubative time and life time estimation model is constructed. The method allows to obtain probabilistic characteristics of life time taking into account distribution of the material and operating parameters. The demonstration of the reliability estimation model worked out for the steam pipe bending with two-phase flow under erosion-corrosion wear (EC) is presented. (Author) 4 refs

  13. Use of Artificial Neural Network for Testing Effectiveness of Intelligent Computing Models for Predicting Shelf Life of Processed Cheese

    Directory of Open Access Journals (Sweden)

    GOYAL Kumar Gyanendra

    2012-10-01

    Full Text Available This paper presents the suitability of artificial neural network (ANN models for predicting the shelf life of processed cheese stored at 7-8ºC. Soluble nitrogen, pH; standard plate count, yeast & mould count, and spore count were input variables, and sensory score was output variable. Mean square error, root mean square error, coefficient of determination and Nash - sutcliffo coefficient were used in order to test the effectiveness of the developed ANN models. Excellent agreement was found between experimental results and these mathematical parameters, thus confirming that ANN models are very effective in predicting the shelf life of processed cheese.

  14. A data-driven fuzzy approach for predicting the remaining useful life in dynamic failure scenarios of a nuclear system

    International Nuclear Information System (INIS)

    This paper presents a similarity-based approach for prognostics of the Remaining Useful Life (RUL) of a system, i.e. the lifetime remaining between the present and the instance when the system can no longer perform its function. Data from failure dynamic scenarios of the system are used to create a library of reference trajectory patterns to failure. Given a failure scenario developing in the system, the remaining time before failure is predicted by comparing by fuzzy similarity analysis its evolution data to the reference trajectory patterns and aggregating their times to failure in a weighted sum which accounts for their similarity to the developing pattern. The prediction on the failure time is dynamically updated as time goes by and measurements of signals representative of the system state are collected. The approach allows for the on-line estimation of the RUL. For illustration, a case study is considered regarding the estimation of RUL in failure scenarios of the Lead Bismuth Eutectic eXperimental Accelerator Driven System (LBE-XADS).

  15. Electrical Resistance of SiC/SiC Ceramic Matrix Composites for Damage Detection and Life-Prediction

    Science.gov (United States)

    Smith, Craig; Morscher, Gregory; Xia, Zhenhai

    2009-01-01

    Ceramic matrix composites (CMC) are suitable for high temperature structural applications such as turbine airfoils and hypersonic thermal protection systems due to their low density high thermal conductivity. The employment of these materials in such applications is limited by the ability to accurately monitor and predict damage evolution. Current nondestructive methods such as ultrasound, x-ray, and thermal imaging are limited in their ability to quantify small scale, transverse, in-plane, matrix cracks developed over long-time creep and fatigue conditions. CMC is a multifunctional material in which the damage is coupled with the material s electrical resistance, providing the possibility of real-time information about the damage state through monitoring of resistance. Here, resistance measurement of SiC/SiC composites under mechanical load at both room temperature monotonic and high temperature creep conditions, coupled with a modal acoustic emission technique, can relate the effects of temperature, strain, matrix cracks, fiber breaks, and oxidation to the change in electrical resistance. A multiscale model can in turn be developed for life prediction of in-service composites, based on electrical resistance methods. Results of tensile mechanical testing of SiC/SiC composites at room and high temperatures will be discussed. Data relating electrical resistivity to composite constituent content, fiber architecture, temperature, matrix crack formation, and oxidation will be explained, along with progress in modeling such properties.

  16. Report on three Genomes to Life Workshops: Data Infrastructure, Modeling and Simulation, and Protein Structure Prediction

    Energy Technology Data Exchange (ETDEWEB)

    Geist, GA

    2003-09-16

    On July 22, 23, 24, 2003, three one day workshops were held in Gaithersburg, Maryland. Each was attended by about 30 computational biologists, mathematicians, and computer scientists who were experts in the respective workshop areas The first workshop discussed the data infrastructure needs for the Genomes to Life (GTL) program with the objective to identify gaps in the present GTL data infrastructure and define the GTL data infrastructure required for the success of the proposed GTL facilities. The second workshop discussed the modeling and simulation needs for the next phase of the GTL program and defined how these relate to the experimental data generated by genomics, proteomics, and metabolomics. The third workshop identified emerging technical challenges in computational protein structure prediction for DOE missions and outlining specific goals for the next phase of GTL. The workshops were attended by representatives from both OBER and OASCR. The invited experts at each of the workshops made short presentations on what they perceived as the key needs in the GTL data infrastructure, modeling and simulation, and structure prediction respectively. Each presentation was followed by a lively discussion by all the workshop attendees. The following findings and recommendations were derived from the three workshops. A seamless integration of GTL data spanning the entire range of genomics, proteomics, and metabolomics will be extremely challenging but it has to be treated as the first-class component of the GTL program to assure GTL's chances for success. High-throughput GTL facilities and ultrascale computing will make it possible to address the ultimate goal of modern biology: to achieve a fundamental, comprehensive, and systematic understanding of life. But first the GTL community needs to address the problem of the massive quantities and increased complexity of biological data produced by experiments and computations. Genome-scale collection, analysis

  17. Network Traffic Prediction based on Particle Swarm BP Neural Network

    Directory of Open Access Journals (Sweden)

    Yan Zhu

    2013-11-01

    Full Text Available The traditional BP neural network algorithm has some bugs such that it is easy to fall into local minimum and the slow convergence speed. Particle swarm optimization is an evolutionary computation technology based on swarm intelligence which can not guarantee global convergence. Artificial Bee Colony algorithm is a global optimum algorithm with many advantages such as simple, convenient and strong robust. In this paper, a new BP neural network based on Artificial Bee Colony algorithm and particle swarm optimization algorithm is proposed to optimize the weight and threshold value of BP neural network. After network traffic prediction experiment, we can conclude that optimized BP network traffic prediction based on PSO-ABC has high prediction accuracy and has stable prediction performance.

  18. 基于黏弹性力学分析和线性累积疲劳损伤理论的钢桥面铺装疲劳寿命预估%Fatigue Life Prediction of Steel Bridge Deck Pavement Based on Viscoelastic Mechanical Analysis and Linear Fatigue Cumulative Damage Law

    Institute of Scientific and Technical Information of China (English)

    赵国云; 闫东波; 磨炼同

    2013-01-01

    -10℃ ,0℃ and 15t: fatigue life of Stone mastic asphalt concrete(SMA) and Epoxy asphalt concret(EAC) are tested to obtain fatigue curves and equations. Dynamic mechanical tests for SMA,GAC, EAC, Eliminator waterproof adhesive layer and modified asphalt emulsion (MAE) are performed with DSR, Q800-TMA and UTM-25 hydraulic servo system to obtain viscoelastic mechanical parameters. Maximum transversal tensile strain of four kinds of deck pavement structures under load and temperature coupling influence are got by means of finite element simulation based on the project of Jiujiang Changjiang River Highway Bridge considering with local traffic and climate characteristics, Prediction of lifetime of four deck pavement structures are made according to the linear cumulative damage law. The results indicate that EAC pavement structure fatigue life is longer than GAC pavement structure,and the later structure is suited for the situation of north climate characteristics in China. Meanwhile,the application of Eliminator waterproof adhesive layer in double EAC concrete pavement structure could increase fatigue life remarkablely.%对常用于钢桥面铺装表层的SMA沥青混凝土和环氧沥青混凝土进行-10℃、0℃和15℃四点弯曲疲劳试验,得出疲劳曲线和疲劳方程;使用动态剪切流变仪(DSR)、Q800动态热机械分析仪(TMA)和UTM-25伺服液压系统对SMA沥青混凝土、浇注式沥青混凝土、环氧沥青混凝土、Eliminator防水黏结层、环氧沥青和改性乳化沥青等常用钢桥面铺装材料进行动态力学试验,获取黏弹性力学参数,并进行有限元数值模拟,得出荷载温度耦合作用下铺装表面最大横向弯拉应变.计算江西九江长江公路大桥不同温度区域下的交通量,根据线性累积疲劳损伤理论预估钢桥面铺装的使用寿命.结果表明:环氧沥青混凝土铺装结构疲劳寿命预测结果优于浇注式沥青混凝土铺装结构,后者更适合于北方

  19. Appreciation and Life Satisfaction: Does Appreciation Uniquely Predict Life Satisfaction above Gender, Coping Skills, Self-Esteem, and Positive Affectivity?

    Science.gov (United States)

    Halle, Joshua Solomon

    2015-01-01

    The primary purpose of this research was to examine whether appreciation explains variance in life satisfaction after controlling for gender, positive affectivity, self-esteem, and coping skills. Two hundred ninety-eight undergraduates went to the informed consent page of the online survey composed of the Appreciation Scale, the Satisfaction With…

  20. Life management of power plant based on structural damage testing

    Energy Technology Data Exchange (ETDEWEB)

    Tallermo, H.; Klevtsov, I. [Thermal Engineering Department of Tallinn Technical University, Tallinn (Estonia); Arras, V. [Eesti Energia, Tallinn (Estonia)

    1998-12-31

    Life management system is based on the valid nowadays in Estonian power plants regulation documentation. The system allows to estimate stress distribution in components, find computational assessment of cumulated creep damage, determine when and where it is necessary to cut off the particular number of microsamples or take replicas. Finally, the real metal condition may be assessed on the basis of metallographic specimen research and reasonable 3-R decision - run, repair, replacement - made on further component use. (orig.) 6 refs.

  1. Comparison of Simple Versus Performance-Based Fall Prediction Models

    Directory of Open Access Journals (Sweden)

    Shekhar K. Gadkaree BS

    2015-05-01

    Full Text Available Objective: To compare the predictive ability of standard falls prediction models based on physical performance assessments with more parsimonious prediction models based on self-reported data. Design: We developed a series of fall prediction models progressing in complexity and compared area under the receiver operating characteristic curve (AUC across models. Setting: National Health and Aging Trends Study (NHATS, which surveyed a nationally representative sample of Medicare enrollees (age ≥65 at baseline (Round 1: 2011-2012 and 1-year follow-up (Round 2: 2012-2013. Participants: In all, 6,056 community-dwelling individuals participated in Rounds 1 and 2 of NHATS. Measurements: Primary outcomes were 1-year incidence of “any fall” and “recurrent falls.” Prediction models were compared and validated in development and validation sets, respectively. Results: A prediction model that included demographic information, self-reported problems with balance and coordination, and previous fall history was the most parsimonious model that optimized AUC for both any fall (AUC = 0.69, 95% confidence interval [CI] = [0.67, 0.71] and recurrent falls (AUC = 0.77, 95% CI = [0.74, 0.79] in the development set. Physical performance testing provided a marginal additional predictive value. Conclusion: A simple clinical prediction model that does not include physical performance testing could facilitate routine, widespread falls risk screening in the ambulatory care setting.

  2. Fatigue life estimation for different notched specimens based on the volumetric approach

    Directory of Open Access Journals (Sweden)

    Esmaeili F.

    2010-06-01

    Full Text Available In this paper, the effects of notch radius for different notched specimens has been studied on the values of stress concentration factor, notch strength reduction factor, and fatigue life duration of the specimens. The material which has been selected for this investigation is Al 2024T3 . Volumetric approach has been applied to obtain the values of notch strength reduction factor and results have been compared with those obtained from the Neuber and Peterson methods. Load controlled fatigue tests of mentioned specimens have been conducted on the 250kN servo-hydraulic Zwick/Amsler fatigue testing machine with the frequency of 10Hz. The fatigue lives of the specimens have also been predicted based on the available smooth S-N curve of Al2024-T3 and also the amounts of notch strength reduction factor which have been obtained from volumetric, Neuber and Peterson methods. The values of stress and strain around the notch roots are required to predict the fatigue life of notched specimens, so Ansys finite element code has been used and non-linear analyses have been performed to obtain the stress and strain distributions around the notches. The plastic deformations of the material have been simulated using multi-linear kinematic hardening and cyclic stress-strain relation. The work here shows that the volumetric approach does a very good job for predicting the fatigue life of the notched specimens.

  3. Implicit theories about willpower predict self-regulation and grades in everyday life.

    Science.gov (United States)

    Job, Veronika; Walton, Gregory M; Bernecker, Katharina; Dweck, Carol S

    2015-04-01

    Laboratory research shows that when people believe that willpower is an abundant (rather than highly limited) resource they exhibit better self-control after demanding tasks. However, some have questioned whether this "nonlimited" theory leads to squandering of resources and worse outcomes in everyday life when demands on self-regulation are high. To examine this, we conducted a longitudinal study, assessing students' theories about willpower and tracking their self-regulation and academic performance. As hypothesized, a nonlimited theory predicted better self-regulation (better time management and less procrastination, unhealthy eating, and impulsive spending) for students who faced high self-regulatory demands. Moreover, among students taking a heavy course load, those with a nonlimited theory earned higher grades, which was mediated by less procrastination. These findings contradict the idea that a limited theory helps people allocate their resources more effectively; instead, it is people with the nonlimited theory who self-regulate well in the face of high demands. PMID:25844577

  4. Tool life prediction under multi-cycle loading conditions: A feasibility study

    Directory of Open Access Journals (Sweden)

    Yuan Xi

    2015-01-01

    Full Text Available In the present research, the friction and wear behaviour of a hard coating were studied by using ball-on-disc tests to simulate the wear process of the coated tools for sheet metal forming process. The evolution of the friction coefficient followed a typical dual-plateau pattern, i.e. at the initial stage of sliding, the friction coefficient was relatively low, followed by a sharp increase due to the breakdown of the coatings after a certain number of cyclic dynamic loadings. This phenomenon was caused by the interactive response between the friction and wear from a coating tribo-system, which has not been addressed so far by metal forming researchers, and constant friction coefficient values are normally used in the FE simulations to represent the complex tribological nature at the contact interfaces. Meanwhile, most of the current FE simulations are single cycle, whereas most sheet metal forming operations are conducted as multi-cycle. Therefore, a novel friction/wear interactive friction model was developed to, simultaneously, characterise the evolutions of friction coefficient and the remaining thickness of the coating layer, to enable the wear life of coated tooling to be predicted. The friction model was then implemented into the FE simulation of a sheet metal forming process for feasibility study.

  5. Rumination predicts heightened responding to stressful life events in major depressive disorder and generalized anxiety disorder.

    Science.gov (United States)

    Ruscio, Ayelet Meron; Gentes, Emily L; Jones, Jason D; Hallion, Lauren S; Coleman, Elizabeth S; Swendsen, Joel

    2015-02-01

    Although studies have documented heightened stress sensitivity in major depressive disorder (MDD) and generalized anxiety disorder (GAD), the mechanisms involved are poorly understood. One possible mechanism is the tendency to ruminate in response to stress. We used ecological momentary assessment to study ruminative thoughts after stressful events in 145 adults with MDD, GAD, comorbid MDD-GAD, or no psychopathology. Diagnosed individuals reported more event-related rumination than controls, even after adjusting for event stressfulness. Rumination was equally common in MDD and GAD and was especially severe among comorbid cases. More rumination immediately after the event predicted poorer affect, more maladaptive behavior, and more MDD and GAD symptoms at the next signal, even when pre-event levels of these variables were controlled. Rumination mediated, but did not moderate, the association of stress with affect and with symptoms. Stress-related rumination was more deleterious for diagnosed than healthy individuals, more intense for more severe clinical cases, and more persistent for cases with a greater temperamental vulnerability for emotional disorders. These results implicate rumination as a mechanism of stress sensitivity and suggest pathways through which it may maintain depression and anxiety in everyday life. PMID:25688429

  6. Traffic Prediction Scheme based on Chaotic Models in Wireless Networks

    Directory of Open Access Journals (Sweden)

    Xiangrong Feng

    2013-09-01

    Full Text Available Based on the local support vector algorithm of chaotic time series analysis, the Hannan-Quinn information criterion and SAX symbolization are introduced. Then a novel prediction algorithm is proposed, which is successfully applied to the prediction of wireless network traffic. For the correct prediction problems of short-term flow with smaller data set size, the weakness of the algorithms during model construction is analyzed by study and comparison to LDK prediction algorithm. It is verified the Hannan-Quinn information principle can be used to calculate the number of neighbor points to replace pervious empirical method, which uses the number of neighbor points to acquire more accurate prediction model. Finally, actual flow data is applied to confirm the accuracy rate of the proposed algorithm LSDHQ. It is testified by our experiments that it also has higher performance in adaptability than that of LSDHQ algorithm.

  7. Bioregenerative life support system for a lunar base

    Science.gov (United States)

    Liu, H.; Wang, J.; Manukovsky, N. S.; Kovalev, V. S.; Gurevich, Yu. L.

    We have studied a modular approach to construction of bioregenerative life support system BLSS for a lunar base using soil-like substrate SLS for plant cultivation Calculations of massflow rates in BLSS were based mostly on a vegetarian diet and biological conversion of plant residues in SLS Plant candidate list for lunar BLSS includes the following basic species rice Oryza sativa soy Glycine max sweet potato Ipomoea batatas and wheat Triticum aestivum To reduce the time necessary for transition of the system to steady state we suggest that the first seeding and sprouting could be made on Earth

  8. Prediction of human pharmacokinetics using physiologically based modeling: a retrospective analysis of 26 clinically tested drugs.

    Science.gov (United States)

    De Buck, Stefan S; Sinha, Vikash K; Fenu, Luca A; Nijsen, Marjoleen J; Mackie, Claire E; Gilissen, Ron A H J

    2007-10-01

    The aim of this study was to evaluate different physiologically based modeling strategies for the prediction of human pharmacokinetics. Plasma profiles after intravenous and oral dosing were simulated for 26 clinically tested drugs. Two mechanism-based predictions of human tissue-to-plasma partitioning (P(tp)) from physicochemical input (method Vd1) were evaluated for their ability to describe human volume of distribution at steady state (V(ss)). This method was compared with a strategy that combined predicted and experimentally determined in vivo rat P(tp) data (method Vd2). Best V(ss) predictions were obtained using method Vd2, providing that rat P(tp) input was corrected for interspecies differences in plasma protein binding (84% within 2-fold). V(ss) predictions from physicochemical input alone were poor (32% within 2-fold). Total body clearance (CL) was predicted as the sum of scaled rat renal clearance and hepatic clearance projected from in vitro metabolism data. Best CL predictions were obtained by disregarding both blood and microsomal or hepatocyte binding (method CL2, 74% within 2-fold), whereas strong bias was seen using both blood and microsomal or hepatocyte binding (method CL1, 53% within 2-fold). The physiologically based pharmacokinetics (PBPK) model, which combined methods Vd2 and CL2 yielded the most accurate predictions of in vivo terminal half-life (69% within 2-fold). The Gastroplus advanced compartmental absorption and transit model was used to construct an absorption-disposition model and provided accurate predictions of area under the plasma concentration-time profile, oral apparent volume of distribution, and maximum plasma concentration after oral dosing, with 74%, 70%, and 65% within 2-fold, respectively. This evaluation demonstrates that PBPK models can lead to reasonable predictions of human pharmacokinetics. PMID:17620347

  9. Implementation of neural network based non-linear predictive

    DEFF Research Database (Denmark)

    Sørensen, Paul Haase; Nørgård, Peter Magnus; Ravn, Ole;

    1998-01-01

    The paper describes a control method for non-linear systems based on generalized predictive control. Generalized predictive control (GPC) was developed to control linear systems including open loop unstable and non-minimum phase systems, but has also been proposed extended for the control of non-linear...... systems. GPC is model-based and in this paper we propose the use of a neural network for the modeling of the system. Based on the neural network model a controller with extended control horizon is developed and the implementation issues are discussed, with particular emphasis on an efficient Quasi......-Newton optimization algorithm. The performance is demonstrated on a pneumatic servo system....

  10. Noncausal spatial prediction filtering based on an ARMA model

    Institute of Scientific and Technical Information of China (English)

    Liu Zhipeng; Chen Xiaohong; Li Jingye

    2009-01-01

    Conventional f-x prediction filtering methods are based on an autoregressive model. The error section is first computed as a source noise but is removed as additive noise to obtain the signal, which results in an assumption inconsistency before and after filtering. In this paper, an autoregressive, moving-average model is employed to avoid the model inconsistency. Based on the ARMA model, a noncasual prediction filter is computed and a self-deconvolved projection filter is used for estimating additive noise in order to suppress random noise. The 1-D ARMA model is also extended to the 2-D spatial domain, which is the basis for noncasual spatial prediction filtering for random noise attenuation on 3-D seismic data. Synthetic and field data processing indicate this method can suppress random noise more effectively and preserve the signal simultaneously and does much better than other conventional prediction filtering methods.

  11. LS-SVR and AGO Based Time Series Prediction Method

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shou-peng; LIU Shan; CHAI Wang-xu; ZHANG Jia-qi; GUO Yang-ming

    2016-01-01

    Recently , fault or health condition prediction of complex systems becomes an interesting research topic.However, it is difficult to establish precise physical model for complex systems , and the time series properties are often necessary to be incorporated for the prediction in practice .Currently ,the LS -SVR is widely adopted for prediction of systems with time series data .In this paper , in order to improve the prediction accuracy, accumulated generating operation (AGO) is carried out to improve the data quality and regularity of raw time series data based on grey system theory;then, the inverse accumulated generating operation ( IAGO) is performed to obtain the prediction results .In addition , due to the reason that appropriate kernel function plays an important role in improving the accuracy of prediction through LS-SVR, a modified Gaussian radial basis function (RBF) is proposed.The requirements of distance functions-based kernel functions are satisfied , which ensure fast damping at the place adjacent to the test point and a moderate damping at infinity .The presented model is applied to the analysis of benchmarks .As indicated by the results , the proposed method is an effective prediction one with good precision .

  12. Health-related quality of life predicts long-term survival in patients with peripheral artery disease

    DEFF Research Database (Denmark)

    Issa, Samson M; Hoeks, Sanne E; Scholte op Reimer, Wilma J M;

    2010-01-01

    We examined whether health-related quality of life (HRQoL) predicts long-term survival in patients with peripheral artery disease (PAD) independent of established prognostic risk factors. In 2004, data on 711 consecutive patients with PAD undergoing vascular surgery were collected from 11 hospitals...

  13. The Best Years of Our Lives? Coping with Stress Predicts School Grades, Life Satisfaction, and Feelings about High School

    Science.gov (United States)

    MacCann, Carolyn; Lipnevich, Anastasiya A.; Burrus, Jeremy; Roberts, Richard D.

    2012-01-01

    This study examines whether problem-focused, emotion-focused, and avoidant coping strategies predict key outcomes in a sample of 354 high school students. The four outcomes considered are: academic achievement, life satisfaction, positive feelings towards school, and negative feelings towards school. Results demonstrate that coping incrementally…

  14. Disaster prediction of coal mine gas based on data mining

    Institute of Scientific and Technical Information of China (English)

    SHAO Liang-shan; FU Gui-xiang

    2008-01-01

    The technique of data mining was provided to predict gas disaster in view of thecharacteristics of coal mine gas disaster and feature knowledge based on gas disaster.The rough set theory was used to establish data mining model of gas disaster prediction,and rough set attributes relations was discussed in prediction model of gas disaster tosupplement the shortages of rough intensive reduction method by using information en-tropy criteria. The effectiveness and practicality of data mining technology in the predictionof gas disaster is confirmed through practical application.

  15. Cloud Based Metalearning System for Predictive Modeling of Biomedical Data

    OpenAIRE

    2014-01-01

    Rapid growth and storage of biomedical data enabled many opportunities for predictive modeling and improvement of healthcare processes. On the other side analysis of such large amounts of data is a difficult and computationally intensive task for most existing data mining algorithms. This problem is addressed by proposing a cloud based system that integrates metalearning framework for ranking and selection of best predictive algorithms for data at hand and open source big data technologies fo...

  16. Cloud Based Metalearning System for Predictive Modeling of Biomedical Data

    Directory of Open Access Journals (Sweden)

    Milan Vukićević

    2014-01-01

    Full Text Available Rapid growth and storage of biomedical data enabled many opportunities for predictive modeling and improvement of healthcare processes. On the other side analysis of such large amounts of data is a difficult and computationally intensive task for most existing data mining algorithms. This problem is addressed by proposing a cloud based system that integrates metalearning framework for ranking and selection of best predictive algorithms for data at hand and open source big data technologies for analysis of biomedical data.

  17. A Modified Fatigue Damage Model for High-Cycle Fatigue Life Prediction

    Directory of Open Access Journals (Sweden)

    Meng Wang

    2016-01-01

    Full Text Available Based on the assumption of quasibrittle failure under high-cycle fatigue for the metal material, the damage constitutive equation and the modified damage evolution equation are obtained with continuum damage mechanics. Then, finite element method (FEM is used to describe the failure process of metal material. The increment of specimen’s life and damage state can be researched using damage mechanics-FEM. Finally, the lifetime of the specimen is got at the given stress level. The damage mechanics-FEM is inserted into ABAQUS with subroutine USDFLD and the Python language is used to simulate the fatigue process of titanium alloy specimens. The simulation results have a good agreement with the testing results under constant amplitude loading, which proves the accuracy of the method.

  18. A criterion for high-cycle fatigue life and fatigue limit prediction in biaxial loading conditions

    Science.gov (United States)

    Pejkowski, Łukasz; Skibicki, Dariusz

    2016-08-01

    This paper presents a criterion for high-cycle fatigue life and fatigue strength estimation under periodic proportional and non-proportional cyclic loading. The criterion is based on the mean and maximum values of the second invariant of the stress deviator. Important elements of the criterion are: function of the non-proportionality of fatigue loading and the materials parameter that expresses the materials sensitivity to non-proportional loading. The methods for the materials parameters determination uses three S-N curves: tension-compression, torsion, and any non-proportional loading proposed. The criterion has been verified using experimental data, and the results are included in the paper. These results should be considered as promising. The paper also includes a proposal for multiaxial fatigue models classification due to the approach for the non-proportionality of loading.

  19. Environment enhanced fatigue crack propagation in metals: Inputs to fracture mechanics life prediction models

    Science.gov (United States)

    Gangloff, Richard P.; Kim, Sang-Shik

    1993-01-01

    This report is a critical review of both environment-enhanced fatigue crack propagation data and the predictive capabilities of crack growth rate models. This information provides the necessary foundation for incorporating environmental effects in NASA FLAGRO and will better enable predictions of aerospace component fatigue lives. The review presents extensive literature data on 'stress corrosion cracking and corrosion fatigue.' The linear elastic fracture mechanics approach, based on stress intensity range (Delta(K)) similitude with microscopic crack propagation threshold and growth rates, provides a basis for these data. Results are presented showing enhanced growth rates for gases (viz., H2 and H2O) and electrolytes (e.g. NaCl and H2O) in aerospace alloys including: C-Mn and heat treated alloy steels, aluminum alloys, nickel-based superalloys, and titanium alloys. Environment causes purely time-dependent accelerated fatigue crack growth above the monotonic load cracking threshold (KIEAC) and promotes cycle-time dependent cracking below (KIEAC). These phenomenon are discussed in terms of hydrogen embrittlement, dissolution, and film rupture crack tip damage mechanisms.

  20. Comparing quality of life dimension in different age decades: prediction for aging

    OpenAIRE

    Vahid Nejati; Khodabakhsh Ahmadi; Maryam Sharifian; Fatemah Shoaee

    2012-01-01

    Background & Objective: Quality of life in different age groups can consider as good predictor of elderly quality of life. The purpose of present study is comparing quality of life in different age decade. Materials & Methods: This cross sectional study performed in 1914 citizens of Tehran with SF36 questionnaire. Sample selection method was multistage classification. We used One Way ANOVA for analysis. Results: Findings show that quality of life dimension reduced in role physical, physical a...

  1. Accurate Multisteps Traffic Flow Prediction Based on SVM

    Directory of Open Access Journals (Sweden)

    Zhang Mingheng

    2013-01-01

    Full Text Available Accurate traffic flow prediction is prerequisite and important for realizing intelligent traffic control and guidance, and it is also the objective requirement for intelligent traffic management. Due to the strong nonlinear, stochastic, time-varying characteristics of urban transport system, artificial intelligence methods such as support vector machine (SVM are now receiving more and more attentions in this research field. Compared with the traditional single-step prediction method, the multisteps prediction has the ability that can predict the traffic state trends over a certain period in the future. From the perspective of dynamic decision, it is far important than the current traffic condition obtained. Thus, in this paper, an accurate multi-steps traffic flow prediction model based on SVM was proposed. In which, the input vectors were comprised of actual traffic volume and four different types of input vectors were compared to verify their prediction performance with each other. Finally, the model was verified with actual data in the empirical analysis phase and the test results showed that the proposed SVM model had a good ability for traffic flow prediction and the SVM-HPT model outperformed the other three models for prediction.

  2. The Cumulative Impact of Nonsevere Life Events Predicts Depression Recurrence during Maintenance Treatment with Interpersonal Psychotherapy

    Science.gov (United States)

    Lenze, Shannon N.; Cyranowski, Jill M.; Thompson, Wesley K.; Anderson, Barbara; Frank, Ellen

    2008-01-01

    Although much research has focused on the role of severe life events as risk factors for depression onset, less is known about the relationship between nonsevere life events and depression recurrence. The current study examined the cumulative effects of nonsevere and positive life events on depression recurrence in an outpatient sample of…

  3. A Human Life-Stage Physiologically Based Pharmacokinetic and Pharmacodynamic Model for Chlorpyrifos: Development and Validation

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jordan N.; Hinderliter, Paul M.; Timchalk, Charles; Bartels, M. J.; Poet, Torka S.

    2014-08-01

    Sensitivity to chemicals in animals and humans are known to vary with age. Age-related changes in sensitivity to chlorpyrifos have been reported in animal models. A life-stage physiologically based pharmacokinetic and pharmacodynamic (PBPK/PD) model was developed to computationally predict disposition of CPF and its metabolites, chlorpyrifos-oxon (the ultimate toxicant) and 3,5,6-trichloro-2-pyridinol (TCPy), as well as B-esterase inhibition by chlorpyrifos-oxon in humans. In this model, age-dependent body weight was calculated from a generalized Gompertz function, and compartments (liver, brain, fat, blood, diaphragm, rapid, and slow) were scaled based on body weight from polynomial functions on a fractional body weight basis. Blood flows among compartments were calculated as a constant flow per compartment volume. The life-stage PBPK/PD model was calibrated and tested against controlled adult human exposure studies. Model simulations suggest age-dependent pharmacokinetics and response may exist. At oral doses ≥ 0.55 mg/kg of chlorpyrifos (significantly higher than environmental exposure levels), 6 mo old children are predicted to have higher levels of chlorpyrifos-oxon in blood and higher levels of red blood cell cholinesterase inhibition compared to adults from equivalent oral doses of chlorpyrifos. At lower doses that are more relevant to environmental exposures, the model predicts that adults will have slightly higher levels of chlorpyrifos-oxon in blood and greater cholinesterase inhibition. This model provides a computational framework for age-comparative simulations that can be utilized to predict CPF disposition and biological response over various postnatal life-stages.

  4. Testing life history predictions in a long-lived seabird: a population matrix approach with improved parameter estimation

    Science.gov (United States)

    Doherty, P.F., Jr.; Schreiber, E.A.; Nichols, J.D.; Hines, J.E.; Link, W.A.; Schenk, G.A.; Schreiber, R.W.

    2004-01-01

    Life history theory and associated empirical generalizations predict that population growth rate (lambda) in long-lived animals should be most sensitive to adult survival; the rates to which lambda is most sensitive should be those with the smallest temporal variances; and stochastic environmental events should most affect the rates to which lambda is least sensitive. To date, most analyses attempting to examine these predictions have been inadequate, their validity being called into question by problems in estimating parameters, problems in estimating the variability of parameters, and problems in measuring population sensitivities to parameters. We use improved methodologies in these three areas and test these life-history predictions in a population of red-tailed tropicbirds (Phaethon rubricauda). We support our first prediction that lambda is most sensitive to survival rates. However the support for the second prediction that these rates have the smallest temporal variance was equivocal. Previous support for the second prediction may be an artifact of a high survival estimate near the upper boundary of 1 and not a result of natural selection canalizing variances alone. We did not support our third prediction that effects of environmental stochasticity (El Ni?o) would most likely be detected in vital rates to which lambda was least sensitive and which are thought to have high temporal variances. Comparative data-sets on other seabirds, within and among orders, and in other locations, are needed to understand these environmental effects.

  5. Fracture mechanics based life assessment in petrochemical plants

    International Nuclear Information System (INIS)

    The increasing use of thick walled pressure vessels in petrochemical plants operating at high pressure under severe service conditions could lead to catastrophic failure. In the Malaysian Institute for Nuclear Technology Research (MINT), initial efforts are underway to apply fracture mechanics approach for assessment of significance of defects detected during periodic in service inspection (ISI) of industrial plants. This paper outlines the integrity management strategy based on fracture mechanics and proposes a new procedure for life assessment of petrochemical plants based on ASME Boiler and Pressure Vessel Code, Section XI, BSI PD 6493:1991, BSI 6539:1994, BSI Standard 7910:1999 and API 579:2000. Essential relevant data required for the assessment is listed. Several methods available for determination of fracture toughness are reviewed with limitations in their application to petrochemical plants. A new non destructive method for determination of fracture toughness based on hardness testing and normalized key roughness curve is given. Results of fracture mechanics based life assessment conducted for 100 mm thick ammonia converter of Ni r o steel and 70 mm thick plat forming reactor vessel of ASTM A 38 7 grade B steel in operational fertilizer and petroleum refining plants are presented. (Author)

  6. A vertical handoff decision algorithm based on ARMA prediction model

    Science.gov (United States)

    Li, Ru; Shen, Jiao; Chen, Jun; Liu, Qiuhuan

    2012-01-01

    With the development of computer technology and the increasing demand for mobile communications, the next generation wireless networks will be composed of various wireless networks (e.g., WiMAX and WiFi). Vertical handoff is a key technology of next generation wireless networks. During the vertical handoff procedure, handoff decision is a crucial issue for an efficient mobility. Based on auto regression moving average (ARMA) prediction model, we propose a vertical handoff decision algorithm, which aims to improve the performance of vertical handoff and avoid unnecessary handoff. Based on the current received signal strength (RSS) and the previous RSS, the proposed approach adopt ARMA model to predict the next RSS. And then according to the predicted RSS to determine whether trigger the link layer triggering event and complete vertical handoff. The simulation results indicate that the proposed algorithm outperforms the RSS-based scheme with a threshold in the performance of handoff and the number of handoff.

  7. Prediction of low-cycle fatigue-life by acoustic emission—1: 2024-T3 aluminum alloy, and —2: 7075-T6 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Baram, J. [Ben-Gurion Univ. of the Negev, Beer Sheva (Israel). Materials Engineering Division; Rosen, M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials and Molecular Research Division

    1981-01-01

    1: In this paper, low-cycle fatigue tests were conducted by tension-tension until rupture, on a 2024-T3 aluminum alloy sheet. Initial crack sizes and orientations in the fatigue specimens were found to be randomly distributed. Acoustic emission was continuously monitored during the tests. Every few hundred cycles, the acoustic signal having the highest peak-amplitude, was recorded as an extremal event for the elapsed period. This high peak-amplitude is related to a fast crack propagation rate through a phenomenological relationship. The extremal peak amplitudes are shown by an ordered statistics treatment, to be extremally distributed. The statistical treatment enables the prediction of the number of cycles left until failure. Predictions performed a posteriori based on results gained early in each fatigue test are in good agreement with actual fatigue lives. Finally, the amplitude distribution analysis of the acoustic signals emitted during cyclic stress appears to be a promising nondestructive method of predicting fatigue life. 2: In this paper, low cycle high stress fatigue tests were conducted by tension-tension on an Alclad 7075-T6 aluminum sheet alloy, until rupture. Initial crack sizes and orientations in the fatigue specimens were randomly distributed. Acoustic emission was continuously monitored during the tests. Extremal peak-amplitudes, equivalent to extremal crack-propagation rates, are shown to be extremally Weibull distributed. The prediction of the number of cycles left until failure is made possible, using an ordered statistics treatment and an experimental equipment parameter obtained in previous experiments (Part 1). The predicted life-times are in good agreement with the actual fatigue lives. Finally, the amplitude distribution analysis of the acoustic signals emitted during cyclic stress has been proven to be a feasible nondestructive method of predicting fatigue life.

  8. Synthetic information prediction system for crisis mine based on GIS

    Institute of Scientific and Technical Information of China (English)

    Yuxin Ye; Ping Yu; Shi Wang; Shuisheng Ye

    2006-01-01

    Reserves of some kinds of the crisis mines will be lack now or from now on, because of lacking seriously reserves of mineral resources and the crisis of exploring bases in support. So that it is urgent to predict, appraise, development and utilize the replaceable resources of the crisis mines. The mineral resources prediction software system of synthetic information is intelligent GIS which is used to quantitative prediction of large-scale synthetic information mineral target. It takes the geological body and the mineral resource body as a unit. And it analyzes the ore deposit genesis and metallotect, knows the spatial distribution laws of the ore deposit and ore body, and establish the prospecting model based on the concept of establishing the three-dimensional space of a mine. This paper will primarily discuss some important problems as follows: the secondary development of various kinds of data(including geology, geophysical prospecting, geochemical prospecting and remote sensing, etc); process synthetically and establish the synthetic information interpretative map base; correspond prospecting model with synthetic information of ore deposit; divided into statistical units of metallogenic information synthetic anomalies based on the synthetic information anomalies of ore control, then research the metallogenic information variable of unit synthetically and make quantitative prediction according to choose the quantitative prediction math model which is suitable to the demands of large-scale precision; at last, finish the target area optimization of ore deposit (body).

  9. CMC Property Variability and Life Prediction Methods for Turbine Engine Component Application

    Science.gov (United States)

    Cheplak, Matthew L.

    2004-01-01

    The ever increasing need for lower density and higher temperature-capable materials for aircraft engines has led to the development of Ceramic Matrix Composites (CMCs). Today's aircraft engines operate with >3000"F gas temperatures at the entrance to the turbine section, but unless heavily cooled, metallic components cannot operate above approx.2000 F. CMCs attempt to push component capability to nearly 2700 F with much less cooling, which can help improve engine efficiency and performance in terms of better fuel efficiency, higher thrust, and reduced emissions. The NASA Glenn Research Center has been researching the benefits of the SiC/SiC CMC for engine applications. A CMC is made up of a matrix material, fibers, and an interphase, which is a protective coating over the fibers. There are several methods or architectures in which the orientation of the fibers can be manipulated to achieve a particular material property objective as well as a particular component geometric shape and size. The required shape manipulation can be a limiting factor in the design and performance of the component if there is a lack of bending capability of the fiber as making the fiber more flexible typically sacrifices strength and other fiber properties. Various analysis codes are available (pcGINA, CEMCAN) that can predict the effective Young's Moduli, thermal conductivities, coefficients of thermal expansion (CTE), and various other properties of a CMC. There are also various analysis codes (NASAlife) that can be used to predict the life of CMCs under expected engine service conditions. The objective of this summer study is to utilize and optimize these codes for examining the tradeoffs between CMC properties and the complex fiber architectures that will be needed for several different component designs. For example, for the pcGINA code, there are six variations of architecture available. Depending on which architecture is analyzed, the user is able to specify the fiber tow size, tow

  10. Creep strain, damage and life prediction for welded 0.5CMV steel

    Energy Technology Data Exchange (ETDEWEB)

    Rantala, J.; Auerkari, P.; Holmstroem, S.; Salonen, J.; Laukkanen, A. (VTT Technical Research Centre of Finland, Espoo (Finland))

    2010-05-15

    Creep damage as cavitation and cracking has historically occurred somewhat earlier in the inspections of steam lines made of 0.5CMV steel, when compared to other low alloy steels. The difference has been attributed to modest creep ductility of 0.5CMV steel, and has resulted in attention paid to inspection and maintenance. As the steel is still being used in vintage plants, it is of interest for users while also serving as a model material that can show some essential features of long term creep in much shorter laboratory testing. Particularly challenging service can combine welded thick-wall components with pre-existing fabrication defects, resulting in an unfavorable combination of high stresses, multi-axial loading, and locally weak material. Examples are shown of the observed damage evolution in welded 0.5CMV steam line material in front of a crack-like defect. Long-term multi-axial loading does not necessarily result in type IV failure of welds, but can also induce creep damage and cracking close to the fusion line. This particularly applies to welds with undermatching weld metal such as those made with consumables corresponding to 2.25Cr-1Mo steel. With the LICON approach, it has been shown that this 3a type of damage can be reproduced in about 5 000 h of multi-axial creep testing, while in plant such damage may require more than 100 000 h of service. The microstructural features of the observed damage and a comparison of uniaxial and CT test data suggest that the LICON approach of life prediction could be applied also for welded components where the location of maximum damage deviates from the type 4 position. (orig.)

  11. Quality of life predicts outcome in a heart failure disease management program.

    LENUS (Irish Health Repository)

    O'Loughlin, Christina

    2012-02-01

    BACKGROUND: Chronic heart failure (HF) is associated with a poor Health Related Quality of Life (HRQoL). HRQoL has been shown to be a predictor of HF outcomes however, variability in the study designs make it difficult to apply these findings to a clinical setting. The aim of this study was to establish if HRQoL is a predictor of long-term mortality and morbidity in HF patients followed-up in a disease management program (DMP) and if a HRQoL instrument could be applied to aid in identifying high-risk patients within a clinical context. METHODS: This is a retrospective analysis of HF patients attending a DMP with 18+\\/-9 months follow-up. Clinical and biochemical parameters were recorded on discharge from index HF admission and HRQoL measures were recorded at 2 weeks post index admission. RESULTS: 225 patients were enrolled into the study (mean age=69+\\/-12 years, male=61%, and 78%=systolic HF). In multivariable analysis, all dimensions of HRQoL (measured by the Minnesota Living with HF Questionnaire) were independent predictors of both mortality and readmissions particularly in patients <80 years. A significant interaction between HRQoL and age (Total((HRQoL))age: p<0.001) indicated that the association of HRQoL with outcomes diminished as age increased. CONCLUSIONS: These data demonstrate that HRQoL is a predictor of outcome in HF patients managed in a DMP. Younger patients (<65 years) with a Total HRQoL score of > or =50 are at high risk of an adverse outcome. In older patients > or =80 years HRQoL is not useful in predicting outcome.

  12. Application of chaotic prediction model based on wavelet transform on water quality prediction

    Science.gov (United States)

    Zhang, L.; Zou, Z. H.; Zhao, Y. F.

    2016-08-01

    Dissolved oxygen (DO) is closely related to water self-purification capacity. In order to better forecast its concentration, the chaotic prediction model, based on the wavelet transform, is proposed and applied to a certain monitoring section of the Mentougou area of the Haihe River Basin. The result is compared with the simple application of the chaotic prediction model. The study indicates that the new model aligns better with the real data and has a higher accuracy. Therefore, it will provide significant decision support for water protection and water environment treatment.

  13. [Predicting suicide or predicting the unpredictable in an uncertain world: Reinforcement Learning Model-Based analysis].

    Science.gov (United States)

    Desseilles, Martin

    2012-01-01

    In general, it appears that the suicidal act is highly unpredictable with the current scientific means available. In this article, the author submits the hypothesis that predicting suicide is complex because it results in predicting a choice, in itself unpredictable. The article proposes a Reinforcement learning model-based analysis. In this model, we integrate on the one hand, four ascending modulatory neurotransmitter systems (acetylcholine, noradrenalin, serotonin, and dopamine) with their regions of respective projections and afferences, and on the other hand, various observations of brain imaging identified until now in the suicidal process.

  14. Multi-Objective Predictive Balancing Control of Battery Packs Based on Predictive Current

    Directory of Open Access Journals (Sweden)

    Wenbiao Li

    2016-04-01

    Full Text Available Various balancing topology and control methods have been proposed for the inconsistency problem of battery packs. However, these strategies only focus on a single objective, ignore the mutual interaction among various factors and are only based on the external performance of the battery pack inconsistency, such as voltage balancing and state of charge (SOC balancing. To solve these problems, multi-objective predictive balancing control (MOPBC based on predictive current is proposed in this paper, namely, in the driving process of an electric vehicle, using predictive control to predict the battery pack output current the next time. Based on this information, the impact of the battery pack temperature caused by the output current can be obtained. Then, the influence is added to the battery pack balancing control, which makes the present degradation, temperature, and SOC imbalance achieve balance automatically due to the change of the output current the next moment. According to MOPBC, the simulation model of the balancing circuit is built with four cells in Matlab/Simulink. The simulation results show that MOPBC is not only better than the other traditional balancing control strategies but also reduces the energy loss in the balancing process.

  15. Prediction on carbon dioxide emissions based on fuzzy rules

    Science.gov (United States)

    Pauzi, Herrini; Abdullah, Lazim

    2014-06-01

    There are several ways to predict air quality, varying from simple regression to models based on artificial intelligence. Most of the conventional methods are not sufficiently able to provide good forecasting performances due to the problems with non-linearity uncertainty and complexity of the data. Artificial intelligence techniques are successfully used in modeling air quality in order to cope with the problems. This paper describes fuzzy inference system (FIS) to predict CO2 emissions in Malaysia. Furthermore, adaptive neuro-fuzzy inference system (ANFIS) is used to compare the prediction performance. Data of five variables: energy use, gross domestic product per capita, population density, combustible renewable and waste and CO2 intensity are employed in this comparative study. The results from the two model proposed are compared and it is clearly shown that the ANFIS outperforms FIS in CO2 prediction.

  16. Predicting cycle 24 using various dynamo-based tools

    Directory of Open Access Journals (Sweden)

    M. Dikpati

    2008-02-01

    Full Text Available Various dynamo-based techniques have been used to predict the mean solar cycle features, namely the amplitude and the timings of onset and peak. All methods use information from previous cycles, including particularly polar fields, drift-speed of the sunspot zone to the equator, and remnant magnetic flux from the decay of active regions. Polar fields predict a low cycle 24, while spot zone migration and remnant flux both lead to predictions of a high cycle 24. These methods both predict delayed onset for cycle 24. We will describe how each of these methods relates to dynamo processes. We will present the latest results from our flux-transport dynamo, including some sensitivity tests and how our model relates to polar fields and spot zone drift methods.

  17. Model-based uncertainty in species range prediction

    DEFF Research Database (Denmark)

    Pearson, R. G.; Thuiller, Wilfried; Bastos Araujo, Miguel;

    2006-01-01

    Aim Many attempts to predict the potential range of species rely on environmental niche (or 'bioclimate envelope') modelling, yet the effects of using different niche-based methodologies require further investigation. Here we investigate the impact that the choice of model can have on predictions......, identify key reasons why model output may differ and discuss the implications that model uncertainty has for policy-guiding applications. Location The Western Cape of South Africa. Methods We applied nine of the most widely used modelling techniques to model potential distributions under current...... and predicted future climate for four species (including two subspecies) of Proteaceae. Each model was built using an identical set of five input variables and distribution data for 3996 sampled sites. We compare model predictions by testing agreement between observed and simulated distributions for the present...

  18. A concept of a component based system to determine pot-plant shelf-life

    DEFF Research Database (Denmark)

    Körner, Oliver; Skou, Anne-Marie Thonning; Aaslyng, Jesper Peter Mazanti;

    2006-01-01

    Plant keeping quality during shelf life is next to genetic attributes also determined by plant treatment. This is attributed to inner plant quality parameters. We expect that a model including information gathered during crop cultivation could be used to predict the inner crop quality. From that...... to calculate the expected keeping quality, or it will be able to apply the system as decision support during plant cultivation. In the latter case, the model-based system can be implemented in a greenhouse climate computer. The concept contains information on climate control strategies, controlled stress...

  19. Are Macro variables good predictors? A prediction based on the number of total medals acquired

    Directory of Open Access Journals (Sweden)

    Shahram Shafiee

    2012-01-01

    Full Text Available A large amount of effort is spent on forecasting the outcome of sporting events. Moreover, there are large quantities of data regarding the outcomes of sporting events and the factors which are assumed to contribute to those outcomes. In this paper we tried to predict the success of nations at the Asian Games through macro-economic, political, social and cultural variables. we used the information of variables include urban population, Education Expenditures, Age Structure, GDP Real Growth Rate, GDP Per Capita, Unemployment Rate, Population, Inflation Average, current account balance, life expectancy at birth and Merchandise Trade for all of the participating countries in Asian Games from 1970 to 2006 in order to build the model and then this model was tested by the information of variables in 2010. The prediction is based on the number of total medals acquired each country. In this research we used WEKA software that is a popular suite of machine learning software written in Java. The value of correlation coefficient between the predicted and original ranks is 90.42%. Neural Network Model, between 28 countries mentioned, predicts their ranks according to the maximum difference between predicted and original ranks of 19 countries (67.85% is 3, the maximum difference between predicted and original ranks of 8 countries (28.57% is between 4 to 6 and the difference between predicted and original ranks of 1 countries (3.57% is more than 6.

  20. NASA's Evolutionary Xenon Thruster (NEXT) Project Qualification Propellant Throughput Milestone: Performance, Erosion, and Thruster Service Life Prediction After 450 kg

    Science.gov (United States)

    Herman, Daniel A.

    2010-01-01

    The NASA s Evolutionary Xenon Thruster (NEXT) program is tasked with significantly improving and extending the capabilities of current state-of-the-art NSTAR thruster. The service life capability of the NEXT ion thruster is being assessed by thruster wear test and life-modeling of critical thruster components, such as the ion optics and cathodes. The NEXT Long-Duration Test (LDT) was initiated to validate and qualify the NEXT thruster propellant throughput capability. The NEXT thruster completed the primary goal of the LDT; namely to demonstrate the project qualification throughput of 450 kg by the end of calendar year 2009. The NEXT LDT has demonstrated 28,500 hr of operation and processed 466 kg of xenon throughput--more than double the throughput demonstrated by the NSTAR flight-spare. Thruster performance changes have been consistent with a priori predictions. Thruster erosion has been minimal and consistent with the thruster service life assessment, which predicts the first failure mode at greater than 750 kg throughput. The life-limiting failure mode for NEXT is predicted to be loss of structural integrity of the accelerator grid due to erosion by charge-exchange ions.

  1. Prediction of fatigue life of high-heat-load components made of oxygen-free copper by comparing with Glidcop

    International Nuclear Information System (INIS)

    By using the strain-range partitioning method, the fatigue life of high-heat-load components made of oxygen-free copper have been successfully predicted within a factor of two. Following a successful study on the prediction of fatigue life of high-heat-load components made of Glidcop, the thermal limitation of oxygen-free copper (OFC), which is used more commonly than Glidcop, has been studied. In addition to its general mechanical properties, the low-cycle-fatigue (LCF) and creep properties of OFC were investigated in detail and compared with those of Glidcop. The breaking mode of OFC, which was observed to be completely different from that of Glidcop in a fatigue fracture experiment, clarified the importance of considering the creep–fatigue interaction. An additional LCF test with compressive strain holding was conducted so that the creep–fatigue life diagram for out-of-phase thermal fatigue could be obtained on the basis of the strain-range partitioning method. The life predicted from elasto-plastic creep analysis agreed well with that determined from the void ratio estimated in the fatigue fracture experiment

  2. Fast prediction unit selection method for HEVC intra prediction based on salient regions

    Science.gov (United States)

    Feng, Lei; Dai, Ming; Zhao, Chun-lei; Xiong, Jing-ying

    2016-07-01

    In order to reduce the computational complexity of the high efficiency video coding (HEVC) standard, a new algorithm for HEVC intra prediction, namely, fast prediction unit (PU) size selection method for HEVC based on salient regions is proposed in this paper. We first build a saliency map for each largest coding unit (LCU) to reduce its texture complexity. Secondly, the optimal PU size is determined via a scheme that implements an information entropy comparison among sub-blocks of saliency maps. Finally, we apply the partitioning result of saliency map on the original LCUs, obtaining the optimal partitioning result. Our algorithm can determine the PU size in advance to the angular prediction in intra coding, reducing computational complexity of HEVC. The experimental results show that our algorithm achieves a 37.9% reduction in encoding time, while producing a negligible loss in Bjontegaard delta bit rate ( BDBR) of 0.62%.

  3. The role of brain/behavioural systems in prediction of quality of life and coping strategies in cancer patients

    Directory of Open Access Journals (Sweden)

    Shala Jangi Goujeh Biglou

    2014-03-01

    Full Text Available Background: It seems that individual differences in personality characteristics are implicated in the incidence and progress of physical diseases and socio-psychological consequences. However, there are a few studies about the role of personality in the prediction of socio-psychological consequences of cancer. The aim of this research was to survey the role of personality in the prediction of socio-psychosocial factors: quality of life and coping strategies. Methods: This research was a descriptive-correlational study in which the sample included fifty cancer patients who were selected through convenience sampling method. To assess the personality differences, quality of life and coping strategies, the Carver and White (1994 BIS/BAS Scales, SF-12 Health Survey and Coping Inventory for Stressful Situation (CISS were used, respectively. The data were analysed by SPSS software using Pearson correlation coefficient and stepwise regression. Results: The findings showed that Both BIS and BAS systems could predict the quality of life (P<0.001, BIS system could explain the emotion-oriented coping strategy (P<0.05 and avoidance-oriented coping stratesy (P<0.01 and BAS system could explain the problem-oriented coping strategy (P<0.001. Conclusion: The findings of this study showed that brain/behavioural systems can predict the quality of life and coping strategies in cancer patients. The identification of these systems in cancer patients can help recognize the persons that are under the risk of poor quality of life or have a higher chance of using inconsistent coping strategies, and execute preventive measures about them.

  4. Pre-processing in AI based Prediction of QSARs

    CERN Document Server

    Patri, Om Prasad

    2009-01-01

    Machine learning, data mining and artificial intelligence (AI) based methods have been used to determine the relations between chemical structure and biological activity, called quantitative structure activity relationships (QSARs) for the compounds. Pre-processing of the dataset, which includes the mapping from a large number of molecular descriptors in the original high dimensional space to a small number of components in the lower dimensional space while retaining the features of the original data, is the first step in this process. A common practice is to use a mapping method for a dataset without prior analysis. This pre-analysis has been stressed in our work by applying it to two important classes of QSAR prediction problems: drug design (predicting anti-HIV-1 activity) and predictive toxicology (estimating hepatocarcinogenicity of chemicals). We apply one linear and two nonlinear mapping methods on each of the datasets. Based on this analysis, we conclude the nature of the inherent relationships betwee...

  5. A NEW ADMISSION CONTROL APPROACH BASED ON PREDICTION

    Institute of Scientific and Technical Information of China (English)

    Lu Kaining; Jin Zhigang; Zou Jun

    2002-01-01

    Admission control plays an important role in providing QoS to network users. Motivated by the measurement-based admission control algorithm, this letter proposed a new admission control approach for integrated service packet network based on traffic prediction. In the letter, FARIMA(p, d, q) models in the admission control algorithm is deployed. A method to simplify the FARIMA model fitting procedure and hence to reduce the time of traffic modeling and prediction is suggested. The feasibility-study experiments show that FARIMA models which have less number of parameters can be used to model and predict actual traffic on quite a large time scale. Simulation results validate the promising approach.

  6. Endpoint Prediction of EAF Based on Multiple Support Vector Machines

    Institute of Scientific and Technical Information of China (English)

    YUAN Ping; MAO Zhi-zhong; WANG Fu-li

    2007-01-01

    The endpoint parameters are very important to the process of EAF steel-making, but their on-line measurement is difficult. The soft sensor technology is widely used for the prediction of endpoint parameters. Based on the analysis of the smelting process of EAF and the advantages of support vector machines, a soft sensor model for predicting the endpoint parameters was built using multiple support vector machines (MSVM). In this model, the input space was divided by subtractive clustering and a sub-model based on LS-SVM was built in each sub-space. To decrease the correlation among the sub-models and to improve the accuracy and robustness of the model, the sub-models were combined by Principal Components Regression. The accuracy of the soft sensor model is perfectly improved. The simulation result demonstrates the practicability and efficiency of the MSVM model for the endpoint prediction of EAF.

  7. Snippet-based relevance predictions for federated web search

    NARCIS (Netherlands)

    Demeester, Thomas; Nguyen, Dong; Trieschnigg, Dolf; Develder, Chris; Hiemstra, Djoerd

    2013-01-01

    How well can the relevance of a page be predicted, purely based on snippets? This would be highly useful in a Federated Web Search setting where caching large amounts of result snippets is more feasible than caching entire pages. The experiments reported in this paper make use of result snippets and

  8. Fatigue Life Prediction of Fiber-Reinforced Ceramic-Matrix Composites with Different Fiber Preforms at Room and Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Longbiao Li

    2016-03-01

    Full Text Available In this paper, the fatigue life of fiber-reinforced ceramic-matrix composites (CMCs with different fiber preforms, i.e., unidirectional, cross-ply, 2D (two dimensional, 2.5D and 3D CMCs at room and elevated temperatures in air and oxidative environments, has been predicted using the micromechanics approach. An effective coefficient of the fiber volume fraction along the loading direction (ECFL was introduced to describe the fiber architecture of preforms. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. Under cyclic fatigue loading, the fiber broken fraction was determined by combining the interface wear model and fiber statistical failure model at room temperature, and interface/fiber oxidation model, interface wear model and fiber statistical failure model at elevated temperatures, based on the assumption that the fiber strength is subjected to two-parameter Weibull distribution and the load carried by broken and intact fibers satisfies the Global Load Sharing (GLS criterion. When the broken fiber fraction approaches the critical value, the composites fatigue fracture.

  9. Multi-Agent Reinforcement Learning Algorithm Based on Action Prediction

    Institute of Scientific and Technical Information of China (English)

    TONG Liang; LU Ji-lian

    2006-01-01

    Multi-agent reinforcement learning algorithms are studied. A prediction-based multi-agent reinforcement learning algorithm is presented for multi-robot cooperation task. The multi-robot cooperation experiment based on multi-agent inverted pendulum is made to test the efficency of the new algorithm, and the experiment results show that the new algorithm can achieve the cooperation strategy much faster than the primitive multiagent reinforcement learning algorithm.

  10. A burnout prediction model based around char morphology

    Energy Technology Data Exchange (ETDEWEB)

    T. Wu; E. Lester; M. Cloke [University of Nottingham, Nottingham (United Kingdom). Nottingham Energy and Fuel Centre

    2005-07-01

    Poor burnout in a coal-fired power plant has marked penalties in the form of reduced energy efficiency and elevated waste material that can not be utilized. The prediction of coal combustion behaviour in a furnace is of great significance in providing valuable information not only for process optimization but also for coal buyers in the international market. Coal combustion models have been developed that can make predictions about burnout behaviour and burnout potential. Most of these kinetic models require standard parameters such as volatile content, particle size and assumed char porosity in order to make a burnout prediction. This paper presents a new model called the Char Burnout Model (ChB) that also uses detailed information about char morphology in its prediction. The model can use data input from one of two sources. Both sources are derived from image analysis techniques. The first from individual analysis and characterization of real char types using an automated program. The second from predicted char types based on data collected during the automated image analysis of coal particles. Modelling results were compared with a different carbon burnout kinetic model and burnout data from re-firing the chars in a drop tube furnace operating at 1300{sup o}C, 5% oxygen across several residence times. An improved agreement between ChB model and DTF experimental data proved that the inclusion of char morphology in combustion models can improve model predictions. 27 refs., 4 figs., 4 tabs.

  11. Lifetime prediction based on Gamma processes from accelerated degradation data

    Institute of Scientific and Technical Information of China (English)

    Wang Haowei; Xu Tingxue; Mi Qiaoli

    2015-01-01

    Accelerated degradation test is a useful approach to predict the product lifetime at the normal use stress level, especially for highly reliable products. Two kinds of the lifetime prediction based on Gamma processes were studied. One was to predict the lifetime of the population from accelerated degradation data, and the other was to predict the lifetime of an individual by taking the accelerated degradation data as prior information. For an extensive application, the Gamma process with a time transformation and random effects was considered. A novel contribution is that a deducing method for determining the relationships between the shape and scale parameters of Gamma processes and accelerated stresses was presented. When predicting the lifetime of an indi-vidual, Bayesian inference methods were adopted to improve the prediction accuracy, in which the conjugate prior distribution and the non-conjugate prior distribution of random parameters were studied. The conjugate prior distribution only considers the random effect of the scale parameter while the non-conjugate prior distribution considers the random effects of both the scale and shape parameter. The application and usefulness of the proposed method was demonstrated by the accelerated degradation data of carbon-film resistors.

  12. Predicting Difficult Laparoscopic Cholecystectomy Based on Clinicoradiological Assessment

    Science.gov (United States)

    Udachan, Tejaswini V; Sasnur, Prasad; Baloorkar, Ramakanth; Sindgikar, Vikram; Narasangi, Basavaraj

    2015-01-01

    Introduction Laparoscopic cholecystectomy (LC) is the gold standard treatment for symptomatic cholelithiasis. However, of all Laparoscopic cholecystectomies, 1-13% requires conversion to an open for various reasons. Thus, for surgeons it would be helpful to establish criteria that would predict difficult laparoscopic cholecystectomy and conversion preoperatively. But there is no clear consensus among the laparoscopic surgeons regarding the parameters predicting the difficult dissection and conversion to open cholecystectomy. Aim To assess the clinical and radiological parameters for predicting the difficult laparoscopic cholecystectomy and its conversion. Materials and Methods This was a prospective study conducted from October 2010 to October 2014. Total of 180 patients meeting the inclusion criteria undergoing LC were included in the study. Four parameters were assessed to predict the difficult LC. These parameters were: 1) Gallbladder wall thickness; 2) Pericholecystic fluid collection; 3) Number of attacks; 4) Total leucocyte count. The statistical analysis was done using Z-test. Results Out of 180 patients included in this study 126 (70%) were easy, 44 (24.44%) were difficult and 3 (5.56%) patients required conversion to open cholecystectomy. The overall conversion rate was 5.6%. The TLC>11000, more than 2 previous attacks of cholecystitis, GB wall thickness of >3mm and Pericholecystic collection were all statistically significant for predicting the difficult LC and its conversion. Conclusion The difficult laparoscopic cholecystectomy and conversion to open surgery can be predicted preoperatively based on number of previous attacks of cholecystitis, WBC count, Gall bladder wall thickness and Pericholecystic collection. PMID:26816942

  13. A burnout prediction model based around char morphology

    Energy Technology Data Exchange (ETDEWEB)

    Tao Wu; Edward Lester; Michael Cloke [University of Nottingham, Nottingham (United Kingdom). School of Chemical, Environmental and Mining Engineering

    2006-05-15

    Several combustion models have been developed that can make predictions about coal burnout and burnout potential. Most of these kinetic models require standard parameters such as volatile content and particle size to make a burnout prediction. This article presents a new model called the char burnout (ChB) model, which also uses detailed information about char morphology in its prediction. The input data to the model is based on information derived from two different image analysis techniques. One technique generates characterization data from real char samples, and the other predicts char types based on characterization data from image analysis of coal particles. The pyrolyzed chars in this study were created in a drop tube furnace operating at 1300{sup o}C, 200 ms, and 1% oxygen. Modeling results were compared with a different carbon burnout kinetic model as well as the actual burnout data from refiring the same chars in a drop tube furnace operating at 1300{sup o}C, 5% oxygen, and residence times of 200, 400, and 600 ms. A good agreement between ChB model and experimental data indicates that the inclusion of char morphology in combustion models could well improve model predictions. 38 refs., 5 figs., 6 tabs.

  14. The Role of Social Relationships in Predicting Loneliness: The National Social Life, Health, and Aging Project

    Science.gov (United States)

    Shiovitz-Ezra, Sharon; Leitsch, Sara A.

    2010-01-01

    The authors explore associations between objective and subjective social network characteristics and loneliness in later life, using data from the National Social Life, Health, and Aging Project, a nationally representative sample of individuals ages 57 to 85 in the United States. Hierarchical linear regression was used to examine the associations…

  15. Acute hepatotoxicity: a predictive model based on focused illumina microarrays.

    Science.gov (United States)

    Zidek, Nadine; Hellmann, Juergen; Kramer, Peter-Juergen; Hewitt, Philip G

    2007-09-01

    Drug-induced hepatotoxicity is a major issue for drug development, and toxicogenomics has the potential to predict toxicity during early toxicity screening. A bead-based Illumina oligonucleotide microarray containing 550 liver specific genes has been developed. We have established a predictive screening system for acute hepatotoxicity by analyzing differential gene expression profiles of well-known hepatotoxic and nonhepatotoxic compounds. Low and high doses of tetracycline, carbon tetrachloride (CCL4), 1-naphthylisothiocyanate (ANIT), erythromycin estolate, acetaminophen (AAP), or chloroform as hepatotoxicants, clofibrate, theophylline, naloxone, estradiol, quinidine, or dexamethasone as nonhepatotoxic compounds, were administered as a single dose to male Sprague-Dawley rats. After 6, 24, and 72 h, livers were taken for histopathological evaluation and for analysis of gene expression alterations. All hepatotoxic compounds tested generated individual gene expression profiles. Based on leave-one-out cross-validation analysis, gene expression profiling allowed the accurate discrimination of all model compounds, 24 h after high dose treatment. Even during the regeneration phase, 72 h after treatment, CCL4, ANIT, and AAP were predicted to be hepatotoxic, and only these three compounds showed histopathological changes at this time. Furthermore, we identified 64 potential marker genes responsible for class prediction, which reflected typical hepatotoxicity responses. These genes and pathways, commonly deregulated by hepatotoxicants, may be indicative of the early characterization of hepatotoxicity and possibly predictive of later hepatotoxicity onset. Two unknown test compounds were used for prevalidating the screening test system, with both being correctly predicted. We conclude that focused gene microarrays are sufficient to classify compounds with respect to toxicity prediction. PMID:17522070

  16. Prediction of eukaryotic gene structures based on multilevel optimization

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yanhong; YANG Lei; WANG Hui; LU Feng; WAN Honghui

    2004-01-01

    Computational gene structure prediction, which is valuable for finding new genes and understanding the composition of genomes, plays a very important role in various kinds of genome projects. For eukaryotic gene structures, however, the prediction accuracy of existing methods is still limited. This paper presents a method of predicting eukaryotic gene structures based on multilevel optimization. The complicated problem of predicting gene structure in eukaryotic DNA sequence containing multiple genes can be decomposed into a series of sub-problems at several levels with decreasing complexity, including the gene level (single-exon gene, multi-exon gene), the element level (exon, intron, etc.), and the feature level (functional site signals, codon usage preference, etc.). On the basis of this decomposition, a multilevel model for the prediction of complex gene structures is created by a multilevel optimization process, in which the models dealing with sub-problems at low complexity level are first optimized respectively, and then optimally combined together to form models for those sub-problems at higher complexity level. Based on the multilevel model, a dynamic programming algorithm is designed to search for optimal gene structures from DNA sequences, and a new program GeneKey (1.0) for the prediction of eukaryotic gene structures is developed. Testing results with widely used datasets demonstrate that the prediction accuracies of GeneKey (1.0) at the nucleotide level, exon level and gene level are all higher than that of the well known program GENSCAN. A web server of GeneKey(1.0) is available at http://infosci.hust.edu.cn

  17. Remaining Life Prediction Method Research of Tank Bottom Corrosion Based on Risk and Acoustic Emission Testing Data Analysis%基于风险与声发射检测数据分析的储罐底板腐蚀剩余寿命预测方法研究

    Institute of Scientific and Technical Information of China (English)

    戴光; 邱枫; 张颖; 赵永涛; 刘延军

    2014-01-01

    Basing on amplitude distribution theory , the statistical theory , bringing in risk concept , the acoustic emission testing and magnetic flux leakage testing data of tank bottom corrosion were comprehen -sively analysed ,and then the quantification method of the acoustic emission parameter based on the testing data of the magnetic flux leakage which was about tank bottom corrosion was got .By the analysis of 10 tanks which are in a region and the medium are crude oil , the acoustic emission typical parameters for tank bottom corrosion quantitative relationship was obtained ,the relationship of acoustic emission activity and risk corrosion rate CRP is y=13514.65x,and the evaluation accuracy of the model is 90.22%.The relationship model of true corrosion pace CTP and risk corrosion pace CRP has been established ,which is z=12.14x,the conclusion that the 12 times of the CRP is about the worst part of the tank bottom corro-sion rate was obtained .Testing the tanks which need evaluate with acoustic emission ,using the evaluation model,CRP can be got and then management corrosion rate of CMP can be got ,according to API 653-2009 ,the remaining life of tank bottom can be predicted .%基于振幅分布理论、统计理论,引入风险概念,综合分析储罐底板腐蚀的声发射检测和漏磁检测数据,得到基于漏磁检测数据的声发射参量对储罐底板腐蚀的量化方法。通过对10台样本储罐的分析,得到某一地区介质为原油的一类储罐的声发射典型参量对储罐底板腐蚀的量化关系,即声发射活度与风险腐蚀速率(CRP)的关系为y=13514.65x,该模型的评价准确率为90.22%。建立实际腐蚀速率(CTP)与CRP的关系模型,为z=12.14x,得到CRP的12倍约为储罐底板腐蚀最严重部位的腐蚀速率的结论。这样对待评估储罐进行声发射检测,利用声发射量化评价模型,可得到CRP,进而得到管理腐蚀速率(CMP),参照API 653

  18. Perceptual Negativity Predicts Greater Reactivity to Negative Events in Daily Life.

    Science.gov (United States)

    Robinson, Michael D; Liu, Tianwei

    2013-11-01

    Reinforcement sensitivity theory includes the idea that people differ in their sensitivity to negative events, but relevant process-based assessments have not been developed. The present studies assessed sensitivity to negative events in terms of the extent to which negative word stimuli were perceived to be larger than neutral word stimuli. There was a general tendency to overestimate the size of negative relative to neutral words, but individuals differed substantially in this form of what is termed perceptual negativity. Of more importance, two studies (total N = 151) found systematic relationships between individual differences in perceptual negativity and reactivity to negative events in daily diary protocols. Study 1 found that within-person variations in the occurrence of daily negative events undermined goal-related optimism to a greater extent at higher, relative to lower, levels of perceptual negativity. Study 2 conceptually replicated this interaction in the context of within-person associations between the occurrence of daily negative events and antisocial behavior. These findings are important in advancing reinforcement sensitivity theory, in operationalizing a particular component of it, and in extending it to reactivity processes in daily life. PMID:24163492

  19. FKBP5 genotype interacts with early life trauma to predict heavy drinking in college students.

    Science.gov (United States)

    Lieberman, Richard; Armeli, Stephen; Scott, Denise M; Kranzler, Henry R; Tennen, Howard; Covault, Jonathan

    2016-09-01

    Alcohol use disorder (AUD) is debilitating and costly. Identification and better understanding of risk factors influencing the development of AUD remain a research priority. Although early life exposure to trauma increases the risk of adulthood psychiatric disorders, including AUD, many individuals exposed to early life trauma do not develop psychopathology. Underlying genetic factors may contribute to differential sensitivity to trauma experienced in childhood. The hypothalamic-pituitary-adrenal (HPA) axis is susceptible to long-lasting changes in function following childhood trauma. Functional genetic variation within FKBP5, a gene encoding a modulator of HPA axis function, is associated with the development of psychiatric symptoms in adulthood, particularly among individuals exposed to trauma early in life. In the current study, we examined interactions between self-reported early life trauma, past-year life stress, past-year trauma, and a single nucleotide polymorphism (rs1360780) in FKBP5 on heavy alcohol consumption in a sample of 1,845 college students from two university settings. Although we found no effect of early life trauma on heavy drinking in rs1360780*T-allele carriers, rs1360780*C homozygotes exposed to early life trauma had a lower probability of heavy drinking compared to rs1360780*C homozygotes not exposed to early life trauma (P < 0.01). The absence of an interaction between either current life stress or past-year trauma, and FKBP5 genotype on heavy drinking suggests that there exists a developmental period of susceptibility to stress that is moderated by FKBP5 genotype. These findings implicate interactive effects of early life trauma and FKBP5 genetic variation on heavy drinking. © 2016 Wiley Periodicals, Inc. PMID:27196697

  20. Quality of life following endonasal skull base surgery.

    Science.gov (United States)

    Pant, Harshita; Bhatki, Amol M; Snyderman, Carl H; Vescan, Allan D; Carrau, Ricardo L; Gardner, Paul; Prevedello, Daniel; Kassam, Amin B

    2010-01-01

    The importance of quality of life (QOL) outcomes following treatments for head and neck tumors are now increasingly appreciated and measured to improve medical and surgical care for these patients. An understanding of the definitions in the setting of health care and the use of appropriate QOL instruments and measures are critical to obtain meaningful information that guides decision making in various aspects of patient health care. QOL outcomes following cranial base surgery is only recently being defined. In this article, we describe the current published data on QOL outcomes following cranial base surgery and provide preliminary prospective data on QOL outcomes and sinonasal morbidity in patients who underwent endonasal cranial base surgery for management of various skull base tumors at our institution. We used a disease-specific multidimensional instrument to measure QOL outcomes in these patients. Our results show that although sinonasal morbidity is increased, this is temporary, and the vast majority of patients have a very good QOL by 4 to 6 months after endonasal approach to the cranial base. PMID:20592856

  1. Control of Unknown Chaotic Systems Based on Neural Predictive Control

    Institute of Scientific and Technical Information of China (English)

    LIDong-Mei; WANGZheng-Ou

    2003-01-01

    We introduce the predictive control into the control of chaotic system and propose a neural network control algorithm based on predictive control. The proposed control system stabilizes the chaotic motion in an unknown chaotic system onto the desired target trajectory. The proposed algorithm is simple and its convergence speed is much higher than existing similar algorithms. The control system can control hyperchaos. We analyze the stability of the control system and prove the convergence property of the neural controller. The theoretic derivation and simulations demonstrate the effectiveness of the algorithm.

  2. Comparing model predictions for ecosystem-based management

    DEFF Research Database (Denmark)

    Jacobsen, Nis Sand; Essington, Timothy E.; Andersen, Ken Haste

    2016-01-01

    Ecosystem modeling is becoming an integral part of fisheries management, but there is a need to identify differences between predictions derived from models employed for scientific and management purposes. Here, we compared two models: a biomass-based food-web model (Ecopath with Ecosim (Ew...... of forage fisheries removal. In both cases, the differences are due to the presumed degree of trophic overlap between juveniles of large-bodied fish and adult stages of forage fish. These differences highlight how each model’s emphasis on distinct details of ecological processes affects its predictions...

  3. Control of Unknown Chaotic Systems Based on Neural Predictive Control

    Institute of Scientific and Technical Information of China (English)

    LI Dong-Mei; WANG Zheng-Ou

    2003-01-01

    We introduce the predictive control into the control of chaotic system and propose a neural networkcontrol algorithm based on predictive control. The proposed control system stabilizes the chaotic motion in an unknownchaotic system onto the desired target trajectory. The proposed algorithm is simple and its convergence speed is muchhigher than existing similar algorithms. The control system can control hyperchaos. We analyze the stability of thecontrol system and prove the convergence property of the neural controller. The theoretic derivation and simulationsdemonstrate the effectiveness of the algorithm.

  4. Prediction of Banking Systemic Risk Based on Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Shouwei Li

    2013-01-01

    Full Text Available Banking systemic risk is a complex nonlinear phenomenon and has shed light on the importance of safeguarding financial stability by recent financial crisis. According to the complex nonlinear characteristics of banking systemic risk, in this paper we apply support vector machine (SVM to the prediction of banking systemic risk in an attempt to suggest a new model with better explanatory power and stability. We conduct a case study of an SVM-based prediction model for Chinese banking systemic risk and find the experiment results showing that support vector machine is an efficient method in such case.

  5. Analysis of fault detection method based on predictive filter approach

    Institute of Scientific and Technical Information of China (English)

    LI Ji; ZHANG Hongyue

    2005-01-01

    A new detection method for component faults based on predictive filters together with the fault detectability, false alarm rate, missed alarm rate and upper bound of detection time are proposed. The efficiency of the method is illustrated by a simulation example of a second-order system. It is shown that the fault detection method using predictive filters has a small delay, a low false alarm rate and a low missed alarm rate. Furthermore the filter can give accurate estimates of states even after a fault occurs. The real-time estimation provided by this method can also be used for fault tolerant control.

  6. Environmental education - an approach based on the concept of life

    Directory of Open Access Journals (Sweden)

    J. Fourie

    1990-10-01

    Full Text Available Environmental education is described as an enterprise aiming at a philosophy of life and therefore as a matter of life. This suggests the concept of life as a natural foundation for an approach to environmental education. Therefore a reflection on the phenomenon of life is offered in which the 'philosophy of life' or vitalist philosophy is reviewed. It is argued that life is a multi-levelled phenomenon and that a monolithic view of life is inadequate. A functional definition of life is proposed in which the microbiological description of life, its link with the abiotic aspect of reality, its other relationships and its spiritual potential are respected. This is used as the ground for an exemplary discussion of life at the levels suggested by the philosophical reflection, viz. life and the individual (which concentrates mainly on the biological aspect, life and the community (concentrating on the social aspect, life and the ecosystem (concentrating primarily on the relationship between abiotic and biotic, and life and the cosmos (which reaches the limit of the authors' task. The need for an ethic is related to these levels and the idea of responsibility is developed with recourse to ancient texts in which comparable ethical implications for the environment are contained. Finally, some practical suggestions are made for implementing the results of the argument in environmental education.

  7. Predictive Software Measures based on Z Specifications - A Case Study

    Directory of Open Access Journals (Sweden)

    Andreas Bollin

    2012-07-01

    Full Text Available Estimating the effort and quality of a system is a critical step at the beginning of every software project. It is necessary to have reliable ways of calculating these measures, and, it is even better when the calculation can be done as early as possible in the development life-cycle. Having this in mind, metrics for formal specifications are examined with a view to correlations to complexity and quality-based code measures. A case study, based on a Z specification and its implementation in ADA, analyzes the practicability of these metrics as predictors.

  8. Effect of Load Rate on Tensile Strength of Various CFCCs at Elevated Temperatures: An Approach to Life Prediction Testing

    Science.gov (United States)

    Choi, Sung R.; Gyekenyesi, John P.

    2001-01-01

    Strength of three continuous fiber-reinforced ceramic composites, including SiC/CAS-11, SiC/MAS-5 and SiC/SiC, was determined as a function of test rate in air at 1100 - 1200 C. All three composite materials exhibited a strong dependency of strength on test rate, similar to the behavior observed in many advanced monolithic ceramics at elevated temperatures. The application of the preloading technique as well as the prediction of life from one loading configuration (constant stress-rate) to another (constant stress loading) suggested that the overall macroscopic failure mechanism of the composites would be the one governed by a power-law tyw of damage evolution/accumulation, analogous to slow crack growth commonly observed in advanced monolithic ceramics. It was further found that constant stress-rate testing could be used as an alternative to life prediction test methodology even for the composite materials at least for the short range of lifetime.

  9. Health-related quality of life and its predictive role for analgesic effect in patients with painful polyneuropathy

    DEFF Research Database (Denmark)

    Otto, Marit; Bach, Flemming W; Jensen, Troels S;

    2007-01-01

    Painful polyneuropathy is a common neuropathic pain condition. The present study describes health-related quality of life (HRQL) in a sample of patients with painful polyneuropathy of different origin and the possible predictive role of HRQL for analgesic effect. Ninety-three patients with a diag......Painful polyneuropathy is a common neuropathic pain condition. The present study describes health-related quality of life (HRQL) in a sample of patients with painful polyneuropathy of different origin and the possible predictive role of HRQL for analgesic effect. Ninety-three patients...... with a diagnosis of painful polyneuropathy were included in the analysis. Data were obtained from three randomised, placebo-controlled cross-over studies testing the effect of different drugs on polyneuropathic pain (St. John's wort, venlafaxine/imipramine and valproic acid). Patients completed a HRQL...

  10. Prediction of potential drug targets based on simple sequence properties

    Directory of Open Access Journals (Sweden)

    Lai Luhua

    2007-09-01

    Full Text Available Abstract Background During the past decades, research and development in drug discovery have attracted much attention and efforts. However, only 324 drug targets are known for clinical drugs up to now. Identifying potential drug targets is the first step in the process of modern drug discovery for developing novel therapeutic agents. Therefore, the identification and validation of new and effective drug targets are of great value for drug discovery in both academia and pharmaceutical industry. If a protein can be predicted in advance for its potential application as a drug target, the drug discovery process targeting this protein will be greatly speeded up. In the current study, based on the properties of known drug targets, we have developed a sequence-based drug target prediction method for fast identification of novel drug targets. Results Based on simple physicochemical properties extracted from protein sequences of known drug targets, several support vector machine models have been constructed in this study. The best model can distinguish currently known drug targets from non drug targets at an accuracy of 84%. Using this model, potential protein drug targets of human origin from Swiss-Prot were predicted, some of which have already attracted much attention as potential drug targets in pharmaceutical research. Conclusion We have developed a drug target prediction method based solely on protein sequence information without the knowledge of family/domain annotation, or the protein 3D structure. This method can be applied in novel drug target identification and validation, as well as genome scale drug target predictions.

  11. FKBP5 genotype interacts with early life trauma to predict heavy drinking in college students.

    Science.gov (United States)

    Lieberman, Richard; Armeli, Stephen; Scott, Denise M; Kranzler, Henry R; Tennen, Howard; Covault, Jonathan

    2016-09-01

    Alcohol use disorder (AUD) is debilitating and costly. Identification and better understanding of risk factors influencing the development of AUD remain a research priority. Although early life exposure to trauma increases the risk of adulthood psychiatric disorders, including AUD, many individuals exposed to early life trauma do not develop psychopathology. Underlying genetic factors may contribute to differential sensitivity to trauma experienced in childhood. The hypothalamic-pituitary-adrenal (HPA) axis is susceptible to long-lasting changes in function following childhood trauma. Functional genetic variation within FKBP5, a gene encoding a modulator of HPA axis function, is associated with the development of psychiatric symptoms in adulthood, particularly among individuals exposed to trauma early in life. In the current study, we examined interactions between self-reported early life trauma, past-year life stress, past-year trauma, and a single nucleotide polymorphism (rs1360780) in FKBP5 on heavy alcohol consumption in a sample of 1,845 college students from two university settings. Although we found no effect of early life trauma on heavy drinking in rs1360780*T-allele carriers, rs1360780*C homozygotes exposed to early life trauma had a lower probability of heavy drinking compared to rs1360780*C homozygotes not exposed to early life trauma (P stress or past-year trauma, and FKBP5 genotype on heavy drinking suggests that there exists a developmental period of susceptibility to stress that is moderated by FKBP5 genotype. These findings implicate interactive effects of early life trauma and FKBP5 genetic variation on heavy drinking. © 2016 Wiley Periodicals, Inc.

  12. Self-Concept Clarity and Religious Orientations: Prediction of Purpose in Life and Self-Esteem

    OpenAIRE

    Błażek, Magdalena; Besta, Tomasz

    2010-01-01

    The present study concerns the relationship between self-concept clarity, religiosity, and well-being, as well as the mediating influence of religiosity on the relationship between self-concept clarity and sense of meaning in life and self-esteem. Self-concept clarity was found to be a significant predictor of sense of meaning in life and self-esteem; intrinsic religious orientation was found to be a predictor of sense of meaning in life, while the quest religious orientation was a predictor ...

  13. Prediction Research of Red Tide Based on Improved FCM

    Directory of Open Access Journals (Sweden)

    Xiaomei Hu

    2016-01-01

    Full Text Available Red tides are caused by the combination effects of many marine elements. The complexity of the marine ecosystem makes it hard to find the relationship between marine elements and red tides. The algorithm of fuzzy c-means (FCM can get clear classification of things and expresses the fuzzy state among different things. Therefore, a prediction algorithm of red tide based on improved FCM is proposed. In order to overcome the defect of FCM which is overdependent on the initial cluster centers and the objective function, this paper gains the initial cluster centers through the principle of regional minimum data density and the minimum mean distance. The feature weighted cluster center is added to the objective function. Finally, the improved FCM algorithm is applied in the prediction research of red tide, and the results show that the improved FCM algorithm has good denoising ability and high accuracy in the prediction of red tides.

  14. Ontology-based prediction of surgical events in laparoscopic surgery

    Science.gov (United States)

    Katić, Darko; Wekerle, Anna-Laura; Gärtner, Fabian; Kenngott, Hannes; Müller-Stich, Beat Peter; Dillmann, Rüdiger; Speidel, Stefanie

    2013-03-01

    Context-aware technologies have great potential to help surgeons during laparoscopic interventions. Their underlying idea is to create systems which can adapt their assistance functions automatically to the situation in the OR, thus relieving surgeons from the burden of managing computer assisted surgery devices manually. To this purpose, a certain kind of understanding of the current situation in the OR is essential. Beyond that, anticipatory knowledge of incoming events is beneficial, e.g. for early warnings of imminent risk situations. To achieve the goal of predicting surgical events based on previously observed ones, we developed a language to describe surgeries and surgical events using Description Logics and integrated it with methods from computational linguistics. Using n-Grams to compute probabilities of followup events, we are able to make sensible predictions of upcoming events in real-time. The system was evaluated on professionally recorded and labeled surgeries and showed an average prediction rate of 80%.

  15. Reducing the Prediction Horizon in NMPC: An Algorithm Based Approach

    CERN Document Server

    Pannek, Jürgen

    2011-01-01

    In order to guarantee stability, known results for MPC without additional terminal costs or endpoint constraints often require rather large prediction horizons. Still, stable behavior of closed loop solutions can often be observed even for shorter horizons. Here, we make use of the recent observation that stability can be guaranteed for smaller prediction horizons via Lyapunov arguments if more than only the first control is implemented. Since such a procedure may be harmful in terms of robustness, we derive conditions which allow to increase the rate at which state measurements are used for feedback while maintaining stability and desired performance specifications. Our main contribution consists in developing two algorithms based on the deduced conditions and a corresponding stability theorem which ensures asymptotic stability for the MPC closed loop for significantly shorter prediction horizons.

  16. Temperature prediction control based on least squares support vector machines

    Institute of Scientific and Technical Information of China (English)

    Bin LIU; Hongye SU; Weihua HUANG; Jian CHU

    2004-01-01

    A prediction control algorithm is presented based on least squares support vector machines (LS-SVM) model for a class of complex systems with strong nonlinearity.The nonlinear off-line model of the controlled plant is built by LS-SVM with radial basis function (RBF) kernel.In the process of system running,the off-line model is linearized at each sampling instant,and the generalized prediction control (GPC) algorithm is employed to implement the prediction control for the controlled plant.The obtained algorithm is applied to a boiler temperature control system with complicated nonlinearity and large time delay.The results of the experiment verify the effectiveness and merit of the algorithm.

  17. Predictive Control-Based Optimal Nonliear Reentry Guidance Law.

    Directory of Open Access Journals (Sweden)

    S. E. Tablole

    1998-04-01

    Full Text Available This Paper discusses a new nominal riding reentry guidance low design based on a nonlinear optimal predictive control approach. In this method, the error between the actual trajectory and the nominal trajectory is predicted, and a quadratic cost function of these predicted errors is minimised, resulting in an optimal feedback guidance law design. The guidance low thus obtained does not require linearisation of the equations of motion. A nominal trajectory is selected which Satisfies the vehicle constraints and mission objectives. This nominal data is used with actual data to evaluate the guidance low. simulations have been carried out for a planar trajectory for a variety of initial condition errors and also for off nominal conditions and the results are presented.

  18. Prediction of blast-induced air overpressure: a hybrid AI-based predictive model.

    Science.gov (United States)

    Jahed Armaghani, Danial; Hajihassani, Mohsen; Marto, Aminaton; Shirani Faradonbeh, Roohollah; Mohamad, Edy Tonnizam

    2015-11-01

    Blast operations in the vicinity of residential areas usually produce significant environmental problems which may cause severe damage to the nearby areas. Blast-induced air overpressure (AOp) is one of the most important environmental impacts of blast operations which needs to be predicted to minimize the potential risk of damage. This paper presents an artificial neural network (ANN) optimized by the imperialist competitive algorithm (ICA) for the prediction of AOp induced by quarry blasting. For this purpose, 95 blasting operations were precisely monitored in a granite quarry site in Malaysia and AOp values were recorded in each operation. Furthermore, the most influential parameters on AOp, including the maximum charge per delay and the distance between the blast-face and monitoring point, were measured and used to train the ICA-ANN model. Based on the generalized predictor equation and considering the measured data from the granite quarry site, a new empirical equation was developed to predict AOp. For comparison purposes, conventional ANN models were developed and compared with the ICA-ANN results. The results demonstrated that the proposed ICA-ANN model is able to predict blast-induced AOp more accurately than other presented techniques. PMID:26433903

  19. An Agent-Based Model of Institutional Life-Cycles

    Directory of Open Access Journals (Sweden)

    Manuel Wäckerle

    2014-08-01

    Full Text Available We use an agent-based model to investigate the interdependent dynamics between individual agency and emergent socioeconomic structure, leading to institutional change in a generic way. Our model simulates the emergence and exit of institutional units, understood as generic governed social structures. We show how endogenized trust and exogenously given leader authority influences institutional change, i.e., diversity in institutional life-cycles. It turns out that these governed institutions (destructure in cyclical patterns dependent on the overall evolution of trust in the artificial society, while at the same time, influencing this evolution by supporting social learning. Simulation results indicate three scenarios of institutional life-cycles. Institutions may, (1 build up very fast and freeze the artificial society in a stable but fearful pattern (ordered system; (2 exist only for a short time, leading to a very trusty society (highly fluctuating system; and (3 structure in cyclical patterns over time and support social learning due to cumulative causation of societal trust (complex system.

  20. The Attribute for Hydrocarbon Prediction Based on Attenuation

    Science.gov (United States)

    Hermana, Maman; Harith, Z. Z. T.; Sum, C. W.; Ghosh, D. P.

    2014-03-01

    Hydrocarbon prediction is a crucial issue in the oil and gas industry. Currently, the prediction of pore fluid and lithology are based on amplitude interpretation which has the potential to produce pitfalls in certain conditions of reservoir. Motivated by this fact, this work is directed to find out other attributes that can be used to reduce the pitfalls in the amplitude interpretation. Some seismic attributes were examined and studies showed that the attenuation attribute is a better attribute for hydrocarbon prediction. Theoretically, the attenuation mechanism of wave propagation is associated with the movement of fluid in the pore; hence the existence of hydrocarbon in the pore will be represented by attenuation attribute directly. In this paper we evaluated the feasibility of the quality factor ratio of P-wave and S-wave (Qp/Qs) as hydrocarbon indicator using well data and also we developed a new attribute based on attenuation for hydrocarbon prediction -- Normalized Energy Reduction Stack (NERS). To achieve these goals, this work was divided into 3 main parts; estimating the Qp/Qs on well log data, testing the new attribute in the synthetic data and applying the new attribute on real data in Malay Basin data. The result show that the Qp/Qs is better than Poisson's ratio and Lamda over Mu as hydrocarbon indicator. The curve, trend analysis and contrast of Qp/Qs is more powerful at distinguishing pore fluid than Poisson ratio and Lamda over Mu. The NERS attribute was successful in distinguishing the hydrocarbon from brine on synthetic data. Applying this attribute on real data on Malay basin, the NERS attribute is qualitatively conformable with the structure and location where the gas is predicted. The quantitative interpretation of this attribute for hydrocarbon prediction needs to be investigated further.

  1. Non-suicidal self-injury prospectively predicts interpersonal stressful life events and depressive symptoms among adolescent girls.

    Science.gov (United States)

    Burke, Taylor A; Hamilton, Jessica L; Abramson, Lyn Y; Alloy, Lauren B

    2015-08-30

    Non-suicidal self-injury (NSSI) is the deliberate self-harm of one's tissue, engaged in without lethal intent, and occurs frequently among late adolescents. Although research has indicated that NSSI predicts depression, the potential psychosocial mechanisms through which engagement in NSSI makes one susceptible to future depressive symptoms remain unclear. The present study examined whether NSSI increases the risk of experiencing stressful life events, which, in turn, heightens the risk for subsequent depressive symptoms. Drawn from a sample specifically selected for adolescents at high and low risk for developing bipolar spectrum disorders, a total of 110 late-adolescents (mean age=18.74, SD=.69; 73% female) were administered measures of lifetime and past year engagement in NSSI and current depressive symptomatology. Approximately 6 months later, they completed a measure of depressive symptoms and a questionnaire and interview assessing life events that occurred over the 6-month interval. Results suggest that the frequency of lifetime and past year NSSI predicted the occurrence of interpersonal stressful life events beyond the effects of initial depressive symptoms, but only for late adolescent girls. Results further suggest that higher levels of interpersonal stressful life events mediated the relationship between NSSI frequency and prospective increases in depressive symptoms among girls.

  2. Development of an accelerated test design for predicting the service life of the solar array at Mead, Nebraska

    Energy Technology Data Exchange (ETDEWEB)

    Gaines, G.B.; Thomas, R.E.; Noel, G.T.; Shilliday, T.S.; Wood, V.E.; Carmichael, D.C.

    1979-06-07

    This report describes an accelerated test which is designed to predict the life of the 25-kW photovoltaic array installed near Mead, Nebraska. Emphasis is placed on the power-output degradation at the module level and on long-term degradation modes, as appropriate for life prediction of mature devices for which infant failures are few. A quantitative model for accelerating testing using multiple environmental stresses is used to develop the test design. The model accounts for the effects of thermal stress by a relation of the Arrhenius form. This relation is then corrected for the effects of nonthermal environmental stresses such as relative humidity, atmospheric pollutants, and ultraviolet radiation. The test conditions, measurements, and data analyses for the accelerated tests are presented for determining the predicted life of the modules in service at Mead. Constant-temperature, cyclic-temperature, and uv types of tests are specified, incorporating selected levels of relative humidity and chemical contamination and an imposed forward-bias current and static electric field. It is recommended that as a first step in test implementation, the model be selectively validated using identified portions of the accelerated test design.

  3. Neural Network Predictive Control Based Power System Stabilizer

    Directory of Open Access Journals (Sweden)

    Ali Mohamed Yousef

    2012-04-01

    Full Text Available The present study investigates the power system stabilizer based on neural predictive control for improving power system dynamic performance over a wide range of operating conditions. In this study a design and application of the Neural Network Model Predictive Controller (NN-MPC on a simple power system composed of a synchronous generator connected to an infinite bus through a transmission line is proposed. The synchronous machine is represented in detail, taking into account the effect of the machine saliency and the damper winding. Neural network model predictive control combines reliable prediction of neural network model with excellent performance of model predictive control using nonlinear Levenberg-Marquardt optimization. This control system is used the rotor speed deviation as a feedback signal. Furthermore, the using performance system of the proposed controller is compared with the system performance using conventional one (PID controller through simulation studies. Digital simulation has been carried out in order to validate the effectiveness proposed NN-MPC power system stabilizer for achieving excellent performance. The results demonstrate that the effectiveness and superiority of the proposed controller in terms of fast response and small settling time.

  4. A New Particle Swarm Optimization Based Stock Market Prediction Technique

    Directory of Open Access Journals (Sweden)

    Essam El. Seidy

    2016-04-01

    Full Text Available Over the last years, the average person's interest in the stock market has grown dramatically. This demand has doubled with the advancement of technology that has opened in the International stock market, so that nowadays anybody can own stocks, and use many types of software to perform the aspired profit with minimum risk. Consequently, the analysis and prediction of future values and trends of the financial markets have got more attention, and due to large applications in different business transactions, stock market prediction has become a critical topic of research. In this paper, our earlier presented particle swarm optimization with center of mass technique (PSOCoM is applied to the task of training an adaptive linear combiner to form a new stock market prediction model. This prediction model is used with some common indicators to maximize the return and minimize the risk for the stock market. The experimental results show that the proposed technique is superior than the other PSO based models according to the prediction accuracy.

  5. Prediction of future disposal of end-of-life refrigerators containing CFC-11.

    Science.gov (United States)

    Yazici, Burcu; Can, Zehra S; Calli, Baris

    2014-01-01

    The objective of this study was to predict the number of refrigerators containing CFC-11 blown isolation foam and the amount of CFC-11 banked in these refrigerators. By using a Weibull-based survival function, the number of CFC-11 containing and still-functioning refrigerators was estimated to be approximately 1.6 million in 2013 in Turkey. In order to determine the amount of CFC-11 in the isolation foam of these refrigerators, polyurethane (PU) foam samples were taken from a refrigerator manufactured in 1993 and the quantity of CFC-11 was analyzed by a GC-MS. It was determined that 113-195 mg CFC-11/g PU remains in the PU foam depending on the location such as door, sides, top and bottom. Knowing that a mid-sized refrigerator contains 4 kg PU on average, the total amount of PU foam to be disposed of is 6344 tons when the CFC-11 containing refrigerators in Turkey become obsolete in the near future. Furthermore, 717-1237 tons of CFC-11 are expected to be banked in the PU foam of these refrigerators which will exert an equivalent amount of ozone depleting potential (ODP). In addition, the global warming potential will vary between 3.4 and 5.9 million tons of CO2. PMID:24112854

  6. Early Life Growth Predicts Pubertal Development in South African Adolescents123

    Science.gov (United States)

    Norris, Shane A; Martorell, Reynaldo; Mehta, Neil K; Richter, Linda M

    2016-01-01

    Background: Given global trends toward earlier onset of puberty and the adverse psychosocial consequences of early puberty, it is important to understand the childhood predictors of pubertal timing and tempo. Objective: We examined the association between early growth and the timing and tempo of puberty in adolescents in South Africa. Methods: We analyzed prospectively collected data from 1060 boys and 1135 girls participating in the Birth-to-Twenty cohort in Soweto, South Africa. Height-for-age z scores (HAZs) and body mass index–for-age z scores (BMIZs) were calculated based on height (centimeters) and body mass index (kilograms per meter squared) at ages 5 y and 8 y. The development of genitals, breasts, and pubic hair was recorded annually from 9 to 16 y of age with the use of the Tanner sexual maturation scale (SMS). We used latent class growth analysis to identify pubertal trajectory classes and also characterized children as fast or slow developers based on the SMS score at 12 y of age. We used multinomial logistic regression to estimate associations of HAZ and BMIZ at ages 5 and 8 y with pubertal development. Results: We identified 3 classes for pubic hair development (for both girls and boys) and 4 classes for breast (for girls) and genital (for boys) development. In girls, both HAZ and BMIZ at age 5 y were positively associated with pubic hair development [relative risk ratio (RRR): 1.57, P pubic hair development (RRR: 1.78, P < 0.001 and RRR: 1.43, P < 0.01, respectively); HAZ at age 5 y was associated with development of genitals (RRR: 2.19, P < 0.01). Conclusion: In boys and girls, both height and body mass index in early childhood predicted the trajectory of pubertal development. This may provide a tool to identify children at risk of early pubertal onset. PMID:26843589

  7. Chaos Time Series Prediction Based on Membrane Optimization Algorithms

    Directory of Open Access Journals (Sweden)

    Meng Li

    2015-01-01

    Full Text Available This paper puts forward a prediction model based on membrane computing optimization algorithm for chaos time series; the model optimizes simultaneously the parameters of phase space reconstruction (τ,m and least squares support vector machine (LS-SVM (γ,σ by using membrane computing optimization algorithm. It is an important basis for spectrum management to predict accurately the change trend of parameters in the electromagnetic environment, which can help decision makers to adopt an optimal action. Then, the model presented in this paper is used to forecast band occupancy rate of frequency modulation (FM broadcasting band and interphone band. To show the applicability and superiority of the proposed model, this paper will compare the forecast model presented in it with conventional similar models. The experimental results show that whether single-step prediction or multistep prediction, the proposed model performs best based on three error measures, namely, normalized mean square error (NMSE, root mean square error (RMSE, and mean absolute percentage error (MAPE.

  8. Predicting online ratings based on the opinion spreading process

    Science.gov (United States)

    He, Xing-Sheng; Zhou, Ming-Yang; Zhuo, Zhao; Fu, Zhong-Qian; Liu, Jian-Guo

    2015-10-01

    Predicting users' online ratings is always a challenge issue and has drawn lots of attention. In this paper, we present a rating prediction method by combining the user opinion spreading process with the collaborative filtering algorithm, where user similarity is defined by measuring the amount of opinion a user transfers to another based on the primitive user-item rating matrix. The proposed method could produce a more precise rating prediction for each unrated user-item pair. In addition, we introduce a tunable parameter λ to regulate the preferential diffusion relevant to the degree of both opinion sender and receiver. The numerical results for Movielens and Netflix data sets show that this algorithm has a better accuracy than the standard user-based collaborative filtering algorithm using Cosine and Pearson correlation without increasing computational complexity. By tuning λ, our method could further boost the prediction accuracy when using Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE) as measurements. In the optimal cases, on Movielens and Netflix data sets, the corresponding algorithmic accuracy (MAE and RMSE) are improved 11.26% and 8.84%, 13.49% and 10.52% compared to the item average method, respectively.

  9. STRESS-STRAIN FINITE ELEMENT ANALYSIS AND FATIGUE LIFE PREDICTION FOR BOLTED CONNECTIONS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A cyclic plasticity model is used into finite element (FE) method to obtain the details of elastic-plastic stress-strain in the bolts under cyclic axial loading. Two criteria in multiaxial fatigue are employed to predict fatigue lives of bolts. The predicted fatigue lives are in favorable agreement with the experimental results for machined bolts.

  10. Support vector machine-based multi-model predictive control

    Institute of Scientific and Technical Information of China (English)

    Zhejing BA; Youxian SUN

    2008-01-01

    In this paper,a support vector machine-based multi-model predictive control is proposed,in which SVM classification combines well with SVM regression.At first,each working environment is modeled by SVM regression and the support vector machine network-based model predictive control(SVMN-MPC)algorithm corresponding to each environment is developed,and then a multi-class SVM model is established to recognize multiple operating conditions.As for control,the current environment is identified by the multi-class SVM model and then the corresponding SVMN.MPCcontroller is activated at each sampling instant.The proposed modeling,switching and controller design is demonstrated in simulation results.

  11. Stabilisation of difference equations with noisy prediction-based control

    Science.gov (United States)

    Braverman, E.; Kelly, C.; Rodkina, A.

    2016-07-01

    We consider the influence of stochastic perturbations on stability of a unique positive equilibrium of a difference equation subject to prediction-based control. These perturbations may be multiplicative We begin by relaxing the control parameter in the deterministic equation, and deriving a range of values for the parameter over which all solutions eventually enter an invariant interval. Then, by allowing the variation to be stochastic, we derive sufficient conditions (less restrictive than known ones for the unperturbed equation) under which the positive equilibrium will be globally a.s. asymptotically stable: i.e. the presence of noise improves the known effectiveness of prediction-based control. Finally, we show that systemic noise has a "blurring" effect on the positive equilibrium, which can be made arbitrarily small by controlling the noise intensity. Numerical examples illustrate our results.

  12. Predictive Potential Field-Based Collision Avoidance for Multicopters

    Science.gov (United States)

    Nieuwenhuisen, M.; Schadler, M.; Behnke, S.

    2013-08-01

    Reliable obstacle avoidance is a key to navigating with UAVs in the close vicinity of static and dynamic obstacles. Wheel-based mobile robots are often equipped with 2D or 3D laser range finders that cover the 2D workspace sufficiently accurate and at a high rate. Micro UAV platforms operate in a 3D environment, but the restricted payload prohibits the use of fast state-of-the-art 3D sensors. Thus, perception of small obstacles is often only possible in the vicinity of the UAV and a fast collision avoidance system is necessary. We propose a reactive collision avoidance system based on artificial potential fields, that takes the special dynamics of UAVs into account by predicting the influence of obstacles on the estimated trajectory in the near future using a learned motion model. Experimental evaluation shows that the prediction leads to smoother trajectories and allows to navigate collision-free through passageways.

  13. Online Forums Hotspot Prediction Based on Sentiment Analysis

    Directory of Open Access Journals (Sweden)

    V. Murali Bhaskarn

    2012-01-01

    Full Text Available Problem statement: Online forums hotspot prediction is one of the significant research areas in web mining, which can help people make proper decision in daily life. Online forums, news reports and blogs, are containing large volume of public opinion information. Rapid growth of network arouses much attention on public opinion, it is important to analyse the public opinion in time and understands the trends of their opinion correctly. Approach: The sentiment analysis and text mining are important key elements for forecasting the hotspots in online forums. Most of the traditional text mining work on static data sets, while the online hotspot forecasts works on the web information dynamically and timely. The earlier work on text information processing focuses in the factual domain rather than opinion domain. Due to the semi structured or unstructured characteristics of online public opinion, we introduce traditional Vector Space Model (VSM to express them and then use K-means to perform hotspot detection, then we use J48 classifier to perform hotspot forecast. Results: The experimentation is conducted by Rapid Miner tool and performance of proposed method J48 is compared with other method, such as Naive Bayes. The consistency between K-means and J48 is validated using three metrics. They are accuracy, sensitivity and specificity. Conclusion: The experiment helps to identify that K-means and J48 together to predict forums hotspot. The results that have been obtained using J48 present a noticeable consistency with the results achieved by K-means clustering.

  14. Residual life estimation based on a generalized Wiener degradation process

    International Nuclear Information System (INIS)

    The issue of residual life (RL) estimation, which has been widely studied recently, plays an important role in scheduling maintenance. In this work, we present an adaptive method of RL estimation based on a generalized Wiener degradation process which subsumes several existing models as limiting cases. The nonlinearity, the temporal uncertainty, and the product-to-product variability of the degradation are jointly taken into account in the proposed degradation model. Under a mild assumption, an analytical approximation to the probability density function of the RL is derived in a closed-form, which becomes quite useful in maintenance decision making. The unknown parameters of the model that characterize the population-based degradation characteristics are obtained by using the maximum likelihood approach, while the parameters that describe the online product-specific characteristic are estimated by using the Markov chain Monte Carlo (MCMC) method. Once new degradation data information of the target product becomes available, the degradation model is first updated based on the degradation history up to the current time through a strong tracking filter, and then the RL is estimated sequentially. In this way, the RL of a product can be estimated in an adaptive manner. Finally, the validity of the proposed method is demonstrated with an illustrative example concerning fatigue cracks

  15. Mobility Prediction Based Neighborhood Discovery for Mobile Ad Hoc Networks

    OpenAIRE

    Li, Xu; Mitton, Nathalie; Simplot-Ryl, David

    2010-01-01

    Hello protocol is the basic technique for neighborhood discovery in wireless ad hoc networks. It requires nodes to claim their existence/aliveness by periodic `hello' messages. Central to any hello protocol is the determination of `hello' message transmission rate. No fixed optimal rate exists in the presence of node mobility. The rate should in fact adapt to it, high for high mobility and low for low mobility. In this paper, we propose a novel mobility prediction based hello protocol, named ...

  16. Prediction Research of Red Tide Based on Improved FCM

    OpenAIRE

    Xiaomei Hu; Dong Wang; Hewei Qu; Xinran Shi

    2016-01-01

    Red tides are caused by the combination effects of many marine elements. The complexity of the marine ecosystem makes it hard to find the relationship between marine elements and red tides. The algorithm of fuzzy c-means (FCM) can get clear classification of things and expresses the fuzzy state among different things. Therefore, a prediction algorithm of red tide based on improved FCM is proposed. In order to overcome the defect of FCM which is overdependent on the initial cluster centers and...

  17. Seminal Quality Prediction Using Clustering-Based Decision Forests

    Directory of Open Access Journals (Sweden)

    Hong Wang

    2014-08-01

    Full Text Available Prediction of seminal quality with statistical learning tools is an emerging methodology in decision support systems in biomedical engineering and is very useful in early diagnosis of seminal patients and selection of semen donors candidates. However, as is common in medical diagnosis, seminal quality prediction faces the class imbalance problem. In this paper, we propose a novel supervised ensemble learning approach, namely Clustering-Based Decision Forests, to tackle unbalanced class learning problem in seminal quality prediction. Experiment results on real fertility diagnosis dataset have shown that Clustering-Based Decision Forests outperforms decision tree, Support Vector Machines, random forests, multilayer perceptron neural networks and logistic regression by a noticeable margin. Clustering-Based Decision Forests can also be used to evaluate variables’ importance and the top five important factors that may affect semen concentration obtained in this study are age, serious trauma, sitting time, the season when the semen sample is produced, and high fevers in the last year. The findings could be helpful in explaining seminal concentration problems in infertile males or pre-screening semen donor candidates.

  18. 基于修正θ法的长期服役10CrMo910钢主蒸汽管道剩余寿命预测%Residual Life Prediction of Long-service 10CrMo910 Main Steam Pipe Based on Modified θ Projection Concept

    Institute of Scientific and Technical Information of China (English)

    周怡然; 赵建平

    2012-01-01

    Lager number of equipment usually works under the situation of high temperature and high pressure in petrochemical industry, power generation and other industry. Ensure the safety work of equipment is important for the protection of personnel and property safety. The creep properties of heat - resistant steel 10CrMo910 was researched, which is widely used in main steam pipe of power plants. For the long - service main steam pipe, using modified θ projection concept analysis and prediction of the residual life of the steel used more than 200000 hours. It plays a guidance role on safety performance and normal operation for the pipeline which close to the design life.%在石油化工、火力发电等行业,大量的设备承受较高的温度和复杂载荷作用,确保其安全运行对于保障人员和财产安全有重要意义.对广泛应用于电厂主蒸汽管道的耐热钢10CrMo910的蠕变性能进行了研究,针对长期服役的主蒸汽管道,应用修正θ法对服役20余万h的钢材进行了分析及剩余寿命预测,对于寿命后期管道继续服役的安全性和操作有一定的指导意义.

  19. Streambed microstructure predicts evolution of development and life history mode in the plethodontid salamander Eurycea tynerensis

    Directory of Open Access Journals (Sweden)

    Bonett Ronald M

    2006-03-01

    Full Text Available Abstract Background Habitat variation strongly influences the evolution of developmentally flexible traits, and may drive speciation and diversification. The plethodontid salamander Eurycea tynerensis is endemic to the geologically diverse Ozark Plateau of south-central North America, and comprises both strictly aquatic paedomorphic populations (achieving reproductive maturity while remaining in the larval form and more terrestrial metamorphic populations. The switch between developmental modes has occurred many times, but populations typically exhibit a single life history mode. This unique system offers an opportunity to study the specific ecological circumstances under which alternate developmental and life history modes evolve. We use phylogenetic independent contrasts to test for relationships between a key microhabitat feature (streambed sediment and this major life history polymorphism. Results We find streambed microstructure (sediment particle size, type and degree of sorting to be highly correlated with life-history mode. Eurycea tynerensis is paedomorphic in streams containing large chert gravel, but metamorphoses in nearby streams containing poorly sorted, clastic material such as sandstone or siltstone. Conclusion Deposits of large chert gravel create loosely associated streambeds, which provide access to subsurface water during dry summer months. Conversely, streambeds composed of more densely packed sandstone and siltstone sediments leave no subterranean refuge when surface water dries, presumably necessitating metamorphosis and use of terrestrial habitats. This represents a clear example of the relationship between microhabitat structure and evolution of a major developmental and life history trait, and has broad implications for the role of localized ecological conditions on larger-scale evolutionary processes.

  20. Development of an accelerated test design for predicting the service life of the solar array at Mead, Nebraska. Quarterly report

    Energy Technology Data Exchange (ETDEWEB)

    Gaines, G.B.; Thomas, R.E.; Noel, G.T.; Shilliday, T.S.; Wood, V.E.; Carmichael, D.C.

    1979-02-06

    Economic viability requires that photovoltaic arrays should have a service life of 20 years or longer. Qualification and performance tests indicate that presently available photovoltaic modules provide acceptable performance at the time of installation. This study is being conducted as part of a program to develop and validate an accelerated test plan that can be used to predict the useful service life of present and future solar arrays. Previously a methodology was developed for designing an accelerated test program incorporating trade-offs between the cost of each test and its value in reducing the variance in the life prediction for that array. The objective of the present study is to apply this methodology to develop an accelerated test plan to predict the service life of the 25-kW photovoltaic array installed near Mead, Nebraska. Potential long-term degradation modes for the two types of modules in the Mead array have been determined and judgments have been made as to those environmental stresses and combinations of stresses which accelerate the degradation of the power output. Hierarchical trees representing the severity of effects of stresses (test conditions) on eleven individual degradation modes have been constructed and have been pruned of tests judged to be nonessential. Composites of those trees have been developed so that there is now one pruned tree covering eight degradation modes, another covering two degradation modes, and a third covering one degradation mode. These three composite trees form the basis for selection of test conditions in the final test plan which is now being prepared.

  1. Do stressful life events predict medical treatment outcome in first episode of depression?

    DEFF Research Database (Denmark)

    Bock, Camilla; Bukh, Jens Drachmann; Vinberg, Maj;

    2009-01-01

    -II) and the interview of recent life events (IRLE). Medical treatment history was assessed in detail using standardised procedures (TRAQ). Remission was defined as a score Rating Scale, 17 items and a score >or= 4 on TRAQ following (1) first trial of antidepressant treatment (2) two......BACKGROUND: It is unclear whether medical treatment outcome in first episode depression differ for patients with and without stressful life events prior to onset of depression. METHODS: Patients discharged with a diagnosis of a single depressive episode from a psychiatric in- or outpatient hospital......: Medical treatment outcome in first episode depression does not depend on the prevalence of moderate to severe stressful life events prior to symptom onset....

  2. Fatigue Life Prediction of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures. Part II: Experimental Comparisons

    Science.gov (United States)

    Longbiao, Li

    2015-12-01

    This paper follows on from the earlier study (Part I) which investigated the fatigue behavior of unidirectional, cross-ply and 2.5D C/SiC composites at room and elevated temperatures. In this paper, a micromechanics approach to predict the fatigue life S-N curves of fiber-reinforced CMCs has been developed considering the fatigue damage mechanism of interface wear or interface oxidation. Upon first loading to fatigue peak stress, matrix multicracking and fiber/matrix interface debonding occur. The two-parameter Weibull model is used to describe fibers strength distribution. The stress carried by broken and intact fibres on the matrix crack plane under fatigue loading is determined based on the Global Load Sharing (GLS) criterion. The fibres failure probabilities under fatigue loading considering the degradation of interface shear stress and fibres strength have been obtained. When the broken fibres fraction approaches critical value, the composite would fatigue fail. The fatigue life S-N curves of unidirectional, cross-ply and 2.5D C/SiC composites at room and elevated temperatures have been predicted. The predicted results agreed with experimental data.

  3. Neural Network Based Model for Predicting Housing Market Performance

    Institute of Scientific and Technical Information of China (English)

    Ahmed Khalafallah

    2008-01-01

    The United States real estate market is currently facing its worst hit in two decades due to the slowdown of housing sales. The most affected by this decline are real estate investors and home develop-ers who are currently struggling to break-even financially on their investments. For these investors, it is of utmost importance to evaluate the current status of the market and predict its performance over the short-term in order to make appropriate financial decisions. This paper presents the development of artificial neu-ral network based models to support real estate investors and home developers in this critical task. The pa-per describes the decision variables, design methodology, and the implementation of these models. The models utilize historical market performance data sets to train the artificial neural networks in order to pre-dict unforeseen future performances. An application example is analyzed to demonstrate the model capabili-ties in analyzing and predicting the market performance. The model testing and validation showed that the error in prediction is in the range between -2% and +2%.

  4. Reflectance Prediction Modelling for Residual-Based Hyperspectral Image Coding

    Science.gov (United States)

    Xiao, Rui; Gao, Junbin; Bossomaier, Terry

    2016-01-01

    A Hyperspectral (HS) image provides observational powers beyond human vision capability but represents more than 100 times the data compared to a traditional image. To transmit and store the huge volume of an HS image, we argue that a fundamental shift is required from the existing “original pixel intensity”-based coding approaches using traditional image coders (e.g., JPEG2000) to the “residual”-based approaches using a video coder for better compression performance. A modified video coder is required to exploit spatial-spectral redundancy using pixel-level reflectance modelling due to the different characteristics of HS images in their spectral and shape domain of panchromatic imagery compared to traditional videos. In this paper a novel coding framework using Reflectance Prediction Modelling (RPM) in the latest video coding standard High Efficiency Video Coding (HEVC) for HS images is proposed. An HS image presents a wealth of data where every pixel is considered a vector for different spectral bands. By quantitative comparison and analysis of pixel vector distribution along spectral bands, we conclude that modelling can predict the distribution and correlation of the pixel vectors for different bands. To exploit distribution of the known pixel vector, we estimate a predicted current spectral band from the previous bands using Gaussian mixture-based modelling. The predicted band is used as the additional reference band together with the immediate previous band when we apply the HEVC. Every spectral band of an HS image is treated like it is an individual frame of a video. In this paper, we compare the proposed method with mainstream encoders. The experimental results are fully justified by three types of HS dataset with different wavelength ranges. The proposed method outperforms the existing mainstream HS encoders in terms of rate-distortion performance of HS image compression. PMID:27695102

  5. Thermomechanical Fatigue Life Prediction for a Marine Diesel Engine Piston considering Ring Dynamics

    OpenAIRE

    Tao He; Xiqun Lu; Dequan Zou; Yibin Guo; Wanyou Li; Minli Huang

    2014-01-01

    A newly designed marine diesel engine piston was modeled using a precise finite element analysis (FEA). The high cycle fatigue (HCF) safety factor prediction procedure designed in this study incorporated lubrication, thermal, and structure analysis. The piston ring dynamics calculation determined the predicted thickness of lubrication oil film. The film thickness influenced the calculated magnitude of the heat transfer coefficient (HTC) used in the thermal loads analysis. Moreover, the gas pr...

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

    Institute of Scientific and Technical Information of China (English)

    Liu Junqiang; Zhang Malan; Zuo Hongfu; Xie Jiwei

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Liu Junqiang

    2014-10-01

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

  8. Predicting the effective thermal conductivity of carbon nanotube based nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, N N Venkata; Bhunia, Avijit; Sundararajan, T; Das, Sarit K [Department of Mechanical Engineering, Indian Institute of Technology, Madras, Chennai 600 036 (India)

    2008-02-06

    Adding a small volume fraction of carbon nanotubes (CNTs) to a liquid enhances the thermal conductivity significantly. Recent experimental findings report an anomalously wide range of enhancement values that continue to perplex the research community and remain unexplained. In this paper we present a theoretical model based on three-dimensional CNT chain formation (percolation) in the base liquid and the corresponding thermal resistance network. The model considers random CNT orientation and CNT-CNT interaction forming the percolating chain. Predictions are in good agreement with almost all available experimental data. Results show that the enhancement critically depends on the CNT geometry (length), volume fraction, thermal conductivity of the base liquid and the nanofluid (CNT-liquid suspension) preparation technique. Based on the physical mechanism of heat conduction in the nanofluid, we introduce a new dimensionless parameter that alone characterizes the nanofluid thermal conductivity with reasonable accuracy ({approx} {+-} 5%)

  9. STANDARD BASED RELIABILITY PREDICTION OF TRAVELING WAVE TUBE IN COMMUNICATION SATELLITE

    Directory of Open Access Journals (Sweden)

    M. SIVANANDAM

    2011-10-01

    Full Text Available A Traveling Wave Tube (TWT is a vital component of satellite communication transponder. Before launch, it is essential to ensure that TWT meets the life of the satellite in the orbit.. Standard based reliability prediction is fairly accurate, widely used in USA and Europe and specified to the contractors. Part stress and parts count analysis are considered in all the standards. In this paper, part stress analysis based on US Military standard,MIL – HDBK – 217F is considered. Since the standard does not provide the failure rate of individual components used in TWT, Preferred Reliability Practices specified by NASA USA in their documents No PD – ED – 1216 is considered for parts count analysis. The reliability estimated by the above standards does not meet the life of 10 years .In the past five years, tremendous improvements have occurred in the materials,design, fabrication, testing and simulation of TWT. Based on these improvements, reliability is recalculated. The revised reliability estimate meets the life of 10 years and coincides with the reliability claimed by the global suppliers of space TWT.

  10. Profiles of Observed Infant Anger Predict Preschool Behavior Problems: Moderation by Life Stress

    Science.gov (United States)

    Brooker, Rebecca J.; Buss, Kristin A.; Lemery-Chalfant, Kathryn; Aksan, Nazan; Davidson, Richard J.; Goldsmith, H. Hill

    2014-01-01

    Using both traditional composites and novel profiles of anger, we examined associations between infant anger and preschool behavior problems in a large, longitudinal data set (N = 966). We also tested the role of life stress as a moderator of the link between early anger and the development of behavior problems. Although traditional measures of…

  11. Emotional Outlook on Life Predicts Increases in Physical Activity among Initially Inactive Men

    Science.gov (United States)

    Baruth, Meghan; Lee, Duck-Chul; Sui, Xuemei; Church, Timothy S.; Marcus, Bess H.; Wilcox, Sara; Blair, Steven N.

    2011-01-01

    This study examined the relationship between emotional outlook on life and change in physical activity among inactive adults in the Aerobics Center Longitudinal Study. A total of 2,132 sedentary adults completed a baseline medical examination and returned for a follow-up examination at least 6 months later. Participants self-reported physical…

  12. Precocity Predicts Shorter Life for Major League Baseball Players: Confirmation of Mccann's Precocity-Longevity Hypothesis

    Science.gov (United States)

    Abel, Ernest L.; Kruger, Michael L.

    2007-01-01

    We tested McCann's precocity-longevity hypothesis, which proposes that early career achievement is related to premature death, for Major League baseball players (N = 3,760). Age at debut was the definition for precocity. We controlled for possible artifacts of life expectancy selection, the "healthy worker" effect, player position, and body-mass…

  13. Predicting the Job and Life Satisfaction of Italian Teachers: Test of a Social Cognitive Model

    Science.gov (United States)

    Lent, Robert W.; Nota, Laura; Soresi, Salvatore; Ginevra, Maria C.; Duffy, Ryan D.; Brown, Steven D.

    2011-01-01

    This study tested a social cognitive model of work and life satisfaction (Lent & Brown, 2006, 2008) in a sample of 235 Italian school teachers. The model offered good overall fit to the data, though not all individual path coefficients were significant. Three of five predictors (favorable work conditions, efficacy-relevant supports, and…

  14. Recognition of a Life Distribution Based on a Neural Network

    Institute of Scientific and Technical Information of China (English)

    GAO Shang

    2004-01-01

    In general, we describe three different methods to select an appropriate distribution form:bistogram, probability plots, and hypothesis test. The life distribution is recognized by a neural network method. The relationship among life distribution with life data is described through threshold and weight of neural networks. The method is convenient to use. An example is presented to validate this method, and the results are satisfactory.

  15. Advances in Fatigue Life Prediction and Accelerated Test of Rubber Vibration Isolator%橡胶隔振器寿命预测及加速试验研究进展

    Institute of Scientific and Technical Information of China (English)

    孙伟星; 刘山尖; 欧阳昕; 董兴建

    2013-01-01

    The failure modes of rubber vibration isolator and the factors influencing its fatigue life were introduced.The fatigue life prediction method for rubber materials based on fracture energy and S-N curve approaches were summarized.The recent research on fatigue life accelerated test for rubber vibration isolator was presented and the current development trends in rubber fatigue life prediction were prospected.%介绍了橡胶材料的疲劳失效形式及影响橡胶材料抗疲劳性能的因素,总结了基于撕裂能和基于S-N曲线的橡胶材料疲劳寿命预测方法,阐明了橡胶隔振器加速试验研究的现状,展望了未来值得研究的方向.

  16. Partitioning of minimotifs based on function with improved prediction accuracy.

    Directory of Open Access Journals (Sweden)

    Sanguthevar Rajasekaran

    Full Text Available BACKGROUND: Minimotifs are short contiguous peptide sequences in proteins that are known to have a function in at least one other protein. One of the principal limitations in minimotif prediction is that false positives limit the usefulness of this approach. As a step toward resolving this problem we have built, implemented, and tested a new data-driven algorithm that reduces false-positive predictions. METHODOLOGY/PRINCIPAL FINDINGS: Certain domains and minimotifs are known to be strongly associated with a known cellular process or molecular function. Therefore, we hypothesized that by restricting minimotif predictions to those where the minimotif containing protein and target protein have a related cellular or molecular function, the prediction is more likely to be accurate. This filter was implemented in Minimotif Miner using function annotations from the Gene Ontology. We have also combined two filters that are based on entirely different principles and this combined filter has a better predictability than the individual components. CONCLUSIONS/SIGNIFICANCE: Testing these functional filters on known and random minimotifs has revealed that they are capable of separating true motifs from false positives. In particular, for the cellular function filter, the percentage of known minimotifs that are not removed by the filter is approximately 4.6 times that of random minimotifs. For the molecular function filter this ratio is approximately 2.9. These results, together with the comparison with the published frequency score filter, strongly suggest that the new filters differentiate true motifs from random background with good confidence. A combination of the function filters and the frequency score filter performs better than these two individual filters.

  17. Statistics-Based Prediction Analysis for Head and Neck Cancer Tumor Deformation

    Directory of Open Access Journals (Sweden)

    Maryam Azimi

    2012-01-01

    Full Text Available Most of the current radiation therapy planning systems, which are based on pre-treatment Computer Tomography (CT images, assume that the tumor geometry does not change during the course of treatment. However, tumor geometry is shown to be changing over time. We propose a methodology to monitor and predict daily size changes of head and neck cancer tumors during the entire radiation therapy period. Using collected patients' CT scan data, MATLAB routines are developed to quantify the progressive geometric changes occurring in patients during radiation therapy. Regression analysis is implemented to develop predictive models for tumor size changes through entire period. The generated models are validated using leave-one-out cross validation. The proposed method will increase the accuracy of therapy and improve patient's safety and quality of life by reducing the number of harmful unnecessary CT scans.

  18. Towards an evolutionary theory of the origin of life based on kinetics and thermodynamics.

    Science.gov (United States)

    Pascal, Robert; Pross, Addy; Sutherland, John D

    2013-11-01

    A sudden transition in a system from an inanimate state to the living state-defined on the basis of present day living organisms-would constitute a highly unlikely event hardly predictable from physical laws. From this uncontroversial idea, a self-consistent representation of the origin of life process is built up, which is based on the possibility of a series of intermediate stages. This approach requires a particular kind of stability for these stages-dynamic kinetic stability (DKS)-which is not usually observed in regular chemistry, and which is reflected in the persistence of entities capable of self-reproduction. The necessary connection of this kinetic behaviour with far-from-equilibrium thermodynamic conditions is emphasized and this leads to an evolutionary view for the origin of life in which multiplying entities must be associated with the dissipation of free energy. Any kind of entity involved in this process has to pay the energetic cost of irreversibility, but, by doing so, the contingent emergence of new functions is made feasible. The consequences of these views on the studies of processes by which life can emerge are inferred. PMID:24196781

  19. Towards an evolutionary theory of the origin of life based on kinetics and thermodynamics.

    Science.gov (United States)

    Pascal, Robert; Pross, Addy; Sutherland, John D

    2013-11-06

    A sudden transition in a system from an inanimate state to the living state-defined on the basis of present day living organisms-would constitute a highly unlikely event hardly predictable from physical laws. From this uncontroversial idea, a self-consistent representation of the origin of life process is built up, which is based on the possibility of a series of intermediate stages. This approach requires a particular kind of stability for these stages-dynamic kinetic stability (DKS)-which is not usually observed in regular chemistry, and which is reflected in the persistence of entities capable of self-reproduction. The necessary connection of this kinetic behaviour with far-from-equilibrium thermodynamic conditions is emphasized and this leads to an evolutionary view for the origin of life in which multiplying entities must be associated with the dissipation of free energy. Any kind of entity involved in this process has to pay the energetic cost of irreversibility, but, by doing so, the contingent emergence of new functions is made feasible. The consequences of these views on the studies of processes by which life can emerge are inferred.

  20. Link prediction based on local information considering preferential attachment

    Science.gov (United States)

    Zeng, Shan

    2016-02-01

    Link prediction in complex networks has attracted much attention in many fields. In this paper, a common neighbors plus preferential attachment index is presented to estimate the likelihood of the existence of a link between two nodes based on local information of the nearest neighbors. Numerical experiments on six real networks demonstrated the high effectiveness and efficiency of the new index compared with five well-known and widely accepted indices: the common neighbors, resource allocation index, preferential attachment index, local path index and Katz index. The new index provides competitively accurate prediction with local path index and Katz index while has less computational complexity and is more accurate than the other two indices.

  1. Human Posture and Movement Prediction based on Musculoskeletal Modeling

    DEFF Research Database (Denmark)

    Farahani, Saeed Davoudabadi

    2014-01-01

    Abstract This thesis explores an optimization-based formulation, so-called inverse-inverse dynamics, for the prediction of human posture and motion dynamics performing various tasks. It is explained how this technique enables us to predict natural kinematic and kinetic patterns for human posture...... and motion using AnyBody Modeling System (AMS). AMS uses inverse dynamics to analyze musculoskeletal systems and is, therefore, limited by its dependency on input kinematics. We propose to alleviate this dependency by assuming that voluntary postures and movement strategies in humans are guided by a desire...... investigated, a scaling to the mean height and body mass may be sufficient, while other questions require subject-specific models. The movement is parameterized by means of time functions controlling selected degrees-of-freedom (DOF). Subsequently, the parameters of these functions, usually referred...

  2. Adaptive quality prediction of batch processes based on PLS model

    Institute of Scientific and Technical Information of China (English)

    LI Chun-fu; ZHANG Jie; WANG Gui-zeng

    2006-01-01

    There are usually no on-line product quality measurements in batch and semi-batch processes,which make the process control task very difficult.In this paper,a model for predicting the end-product quality from the available on-line process variables at the early stage of a batch is developed using partial least squares (PLS)method.Furthermore,some available mid-course quality measurements are used to rectify the final prediction results.To deal with the problem that the process may change with time,recursive PLS (RPLS) algorithm is used to update the model based on the new batch data and the old model parameters after each batch.An application to a simulated batch MMA polymerization process demonstrates the effectiveness of the proposed method.

  3. Nuclear grade cable thermal life model by time temperature superposition algorithm based on Matlab GUI

    International Nuclear Information System (INIS)

    Background: As nuclear grade cable must endure harsh environment within design life, it is critical to predict cable thermal life accurately owing to thermal aging, which is one of dominant factors of aging mechanism. Purpose: Using time temperature superposition (TTS) method, the aim is to construct nuclear grade cable thermal life model, predict cable residual life and develop life model interactive interface under Matlab GUI. Methods: According to TTS, nuclear grade cable thermal life model can be constructed by shifting data groups at various temperatures to preset reference temperature with translation factor which is determined by non linear programming optimization. Interactive interface of cable thermal life model developed under Matlab GUI consists of superposition mode and standard mode which include features such as optimization of translation factor, calculation of activation energy, construction of thermal aging curve and analysis of aging mechanism., Results: With calculation result comparison between superposition and standard method, the result with TTS has better accuracy than that with standard method. Furthermore, confidence level of nuclear grade cable thermal life with TTS is higher than that with standard method. Conclusion: The results show that TTS methodology is applicable to thermal life prediction of nuclear grade cable. Interactive Interface under Matlab GUI achieves anticipated functionalities. (authors)

  4. Host life history and host-parasite syntopy predict behavioural resistance and tolerance of parasites.

    Science.gov (United States)

    Sears, Brittany F; Snyder, Paul W; Rohr, Jason R

    2015-05-01

    There is growing interest in the role that life-history traits of hosts, such as their 'pace-of-life', play in the evolution of resistance and tolerance to parasites. Theory suggests that, relative to host species that have high syntopy (local spatial and temporal overlap) with parasites, host species with low syntopy should have lower selection pressures for more constitutive (always present) and costly defences, such as tolerance, and greater reliance on more inducible and cheaper defences, such as behaviour. Consequently, we postulated that the degree of host-parasite syntopy, which is negatively correlated with host pace-of-life (an axis reflecting the developmental rate of tadpoles and the inverse of their size at metamorphosis) in our tadpole-parasitic cercarial (trematode) system, would be a negative and positive predictor of behavioural resistance and tolerance, respectively. To test these hypotheses, we exposed seven tadpole species to a range of parasite (cercarial) doses crossed with anaesthesia treatments that controlled for anti-parasite behaviour. We quantified host behaviour, successful and unsuccessful infections, and each species' reaction norm for behavioural resistance and tolerance, defined as the slope between cercarial exposure (or attempted infections) and anti-cercarial behaviours and mass change, respectively. Hence, tolerance is capturing any cost of parasite exposure. As hypothesized, tadpole pace-of-life was a significant positive predictor of behavioural resistance and negative predictor of tolerance, a result that is consistent with a trade-off between behavioural resistance and tolerance across species that warrants further investigation. Moreover, these results were robust to considerations of phylogeny, all possible re-orderings of the three fastest or slowest paced species, and various measurements of tolerance. These results suggest that host pace-of-life and host-parasite syntopy are powerful drivers of both the strength and type

  5. Pharmacokinetic Interactions for Drugs with a Long Half-Life-Evidence for the Need of Model-Based Analysis

    OpenAIRE

    Svensson, Elin M.; Acharya, Chayan; Clauson, Björn; Dooley, Kelly E; Karlsson, Mats O

    2016-01-01

    Pharmacokinetic drug-drug interactions (DDIs) can lead to undesired drug exposure, resulting in insufficient efficacy or aggravated toxicity. Accurate quantification of DDIs is therefore crucial but may be difficult when full concentration-time profiles are problematic to obtain. We have compared non-compartmental analysis (NCA) and model-based predictions of DDIs for long half-life drugs by conducting simulation studies and reviewing published trials, using antituberculosis drug bedaquiline ...

  6. Predicting married and cohabiting couples' futures from their descriptions of stepfamily life.

    Science.gov (United States)

    Slattery, Maddy E; Bruce, Vanessa; Halford, W Kim; Nicholson, Jan M

    2011-08-01

    Stepfamily couples experience specific challenges early in their relationships, (e.g., reaching agreement on the role of the stepparent in parenting). The Oral History Interview for Stepfamilies (OHI-S) was developed to assess spouses' cognitive representations of their adaptation to these challenges. It was hypothesized that their responses would predict future relationship satisfaction and stability. One-hundred and 22 stepfamily couples completed the OHI-S and were assessed on relationship satisfaction and stability at Time 1 and 2.5 years later (Time 2). Time 2 relationship satisfaction and stability were both predicted by the OHI-S at Time 1. Couples' perceptions of the stepfamily and couple relationship predict separation, and suggest there is an opportunity for early intervention to enhance stepfamily couple relationships.

  7. Estimating Stochastic Volatility Models using Prediction-based Estimating Functions

    DEFF Research Database (Denmark)

    Lunde, Asger; Brix, Anne Floor

    In this paper prediction-based estimating functions (PBEFs), introduced in Sørensen (2000), are reviewed and PBEFs for the Heston (1993) stochastic volatility model are derived. The finite sample performance of the PBEF based estimator is investigated in a Monte Carlo study, and compared to the...... performance of the GMM estimator based on conditional moments of integrated volatility from Bollerslev and Zhou (2002). The case where the observed log-price process is contaminated by i.i.d. market microstructure (MMS) noise is also investigated. First, the impact of MMS noise on the parameter estimates from...... the two estimation methods without noise correction are studied. Second, a noise robust GMM estimator is constructed by approximating integrated volatility by a realized kernel instead of realized variance. The PBEFs are also recalculated in the noise setting, and the two estimation methods ability to...

  8. Prediction of adolescent and adult adiposity outcomes from early life anthropometrics

    DEFF Research Database (Denmark)

    Graversen, Lise; Sørensen, Thorkild I A; Gerds, Thomas A;

    2015-01-01

    OBJECTIVES: Maternal body mass index (BMI), birth weight, and preschool BMI may help identify children at high risk of overweight as they are (1) similarly linked to adolescent overweight at different stages of the obesity epidemic, (2) linked to adult obesity and metabolic alterations, and (3......) easily obtainable in health examinations in young children. The aim was to develop early childhood prediction models of adolescent overweight, adult overweight, and adult obesity. METHODS: Prediction models at various ages in the Northern Finland Birth Cohort born in 1966 (NFBC1966) were developed...... a subgroup of children at very high risk of becoming overweight, which may be valuable in public health settings dealing with obesity prevention....

  9. Investigation of Bearing Fatigue Damage Life Prediction Using Oil Debris Monitoring

    Science.gov (United States)

    Dempsey, Paula J.; Bolander, Nathan; Haynes, Chris; Toms, Allison M.

    2011-01-01

    Research was performed to determine if a diagnostic tool for detecting fatigue damage of helicopter tapered roller bearings can be used to determine remaining useful life (RUL). The taper roller bearings under study were installed on the tail gearbox (TGB) output shaft of UH- 60M helicopters, removed from the helicopters and subsequently installed in a bearing spall propagation test rig. The diagnostic tool was developed and evaluated experimentally by collecting oil debris data during spall progression tests on four bearings. During each test, data from an on-line, in-line, inductance type oil debris sensor was monitored and recorded for the occurrence of pitting damage. Results from the four bearings tested indicate that measuring the debris generated when a bearing outer race begins to spall can be used to indicate bearing damage progression and remaining bearing life.

  10. Life Skills-Based HIV Education: Some Virtues and Errors

    Science.gov (United States)

    Clarke, David; Yankah, Ekua; Aggleton, Peter

    2015-01-01

    Since the early 1990s, life skills education has benefitted substantially from international agency advocacy and support, linked to its implementation in several countries as a key component of the education sector response to sexual health and HIV. The concept of life skills was first promoted by the World Health Organization through its…

  11. Childhood conscientiousness predicts the social gradient of smoking in adulthood: a life course analysis

    OpenAIRE

    Pluess, M; Bartley, M

    2015-01-01

    Background and aims The social gradient in smoking is well known, with higher rates among those in less advantaged socioeconomic position. Some recent research has reported that personality characteristics partly explain this gradient. However, the majority of existing work is limited by cross-sectional designs unsuitable to determine whether differences in conscientiousness are a predictor or a product of social inequalities. Adopting a life course perspective, we investigated in the current...

  12. A method for predicting service life of zinc rich primers on carbon steel

    Science.gov (United States)

    Hoppesch, C. W.

    1986-01-01

    The service life of zinc rich primers on carbon steel can be estimated by immersing a primer coated glass slide into an aqueous copper sulfate solution and measuring the amount of zinc that reacts with the copper in 15 minutes. This zinc availability test was used to evaluate eleven primers currently available for which marine beach exposure data was available from previous programs. Results were evaluated and a correlation between zinc availability and ASTM rust grade was shown.

  13. Fatigue Analysis and Life Prediction of Dumpers with Cumulative Fatigue Damage Approach

    Institute of Scientific and Technical Information of China (English)

    LI Shouju; LIU Yingxi; SUN Huiling

    2004-01-01

    A fatigue damage model is developed for evaluating accumulative fatigue damage of dumpers. The loading spectrums acted on dumpers are created according to measured strain data in field. The finite element analysis is carried out for assessing stress distribution and strength characteristics of dumpers. Fatigue damage indexes and service life are calculated by a modified Palmgren-Miner rule. The investigation shows that fatigue notch factor has a significant influence on the calculation of fatigue damage of dumpers.

  14. Predicting First Onset of Depression in Young Girls: Interaction of Diurnal Cortisol and Negative Life Events

    OpenAIRE

    LeMoult, Joelle; Ordaz, Sarah J.; Kircanski, Katharina; Singh, Manpreet K.; Gotlib, Ian H.

    2015-01-01

    Interactions between biological vulnerability and environmental adversity are central to the pathophysiology of depression. Given evidence that the hypothalamic-pituitary-adrenal (HPA) axis influences biological responses to environmental events, in the current longitudinal study we examined HPA-axis functioning, negative life events, and their interaction as predictors of the first onset of depression. At baseline, girls ages 9 to 14 years provided saliva samples to assess levels of diurnal ...

  15. Catastrophizing and fear of tinnitus predict quality of life in patients with chronic tinnitus

    OpenAIRE

    Cima, Rilana FF; Crombez, Geert; Vlaeyen, Johan WS

    2011-01-01

    Objectives: It is well established that catastrophic misinterpretations and fear are involved in the suffering and disability of patients with chronic pain. This study investigated whether similar processes explain suffering and disability in patients with chronic tinnitus. We hypothesized that patients who catastrophically (mis)interpret their tinnitus would be more fearful of tinnitus, more vigilant toward their tinnitus, and report less quality of life. Moreover, tinnitus-related fear was ...

  16. Life stress in adolescence predicts early adult reward-related brain function and alcohol dependence

    OpenAIRE

    Casement, Melynda D.; Shaw, Daniel S.; Sitnick, Stephanie L.; Musselman, Samuel C.; Forbes, Erika E.

    2014-01-01

    Stressful life events increase vulnerability to problematic alcohol use, and they may do this by disrupting reward-related neural circuitry. This is particularly relevant for adolescents because alcohol use rises sharply after mid-adolescence and alcohol abuse peaks at age 20. Adolescents also report more stressors compared with children, and neural reward circuitry may be especially vulnerable to stressors during adolescence because of prefrontal cortex remodeling. Using a large sample of ma...

  17. Self-care and Professional Quality of Life: Predictive Factors among MSW Practitioners

    Directory of Open Access Journals (Sweden)

    Kori R Bloomquist

    2016-02-01

    Full Text Available This study explored the effects of self-care practices and perceptions on positive and negative indicators of professional quality of life, including burnout, secondary traumatic stress, and compassion satisfaction among MSW practitioners. Results reveal that while social workers value and believe self-care is effective in alleviating job-related stress, they engage in self-care on a limited basis. Findings indicate that MSW programs and employers do not teach social workers how to effectively engage in self-care practice. Various domains of self-care practice contribute differently to indicators of professional quality of life. This study sheds light on the under-studied relationship between social worker self-care and professional quality of life, provides insights into the types of activities practiced and not practiced by MSW practitioners, and identifies gaps between perceived value and effective teaching of self-care. Implications exist for social work educators and employers and the potential to support a healthier, sustainable workforce.

  18. Predicting life-cycle adaptation of migratory birds to global climate change

    NARCIS (Netherlands)

    Coppack, T.; Both, C.

    2002-01-01

    Analyses of long-term data indicate that human-caused climatic changes are affecting bird phenology in directions consistent with theoretical predictions. Here, we report on recent trends in the timing of spring arrival and egg laying found within a western European Pied Flycatcher Ficedula hypoleuc

  19. Do Materialism, Intrinsic Aspirations, and Meaning in Life Predict Students' Meanings of Education?

    Science.gov (United States)

    Henderson-King, Donna; Mitchell, Amanda M.

    2011-01-01

    Though there is a deep literature on factors that predict college attendance and on the effects of college attendance on students' development, there has been little research on what education actually means to students themselves. This study was conducted to examine whether materialism, intrinsic aspirations, and the search for meaning in life…

  20. Symptoms of borderline personality disorder predict interpersonal (but not independent) stressful life events in a community sample of older adults.

    Science.gov (United States)

    Powers, Abigail D; Gleason, Marci E J; Oltmanns, Thomas F

    2013-05-01

    Individuals with borderline personality disorder (BPD) often experience stressful life events at a higher frequency than those without BPD. It is less clear what specific types of events are involved in this effect, and it has not been determined whether some features of BPD are more important than others in accounting for this effect. The latter issue is important in light of the heterogeneous nature of this diagnostic construct. These issues were examined in a large, representative community sample of men and women, ages 55-64. Ten Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev., DSM-IV-TR, Washington, DC, American Psychiatric Association, 2000) personality disorders were assessed at baseline using the Structured Interview for DSM-IV Personality: SIDP-IV (B. Pfohl, N. Blum, & M. Zimmerman, 1997, Washington, DC, American Psychiatric Press). Life events were measured at three sequential assessments following baseline at 6-month (N = 1,294), 12-month (N = 1,070), and 18-month (N = 837) follow-ups. Stressful life events were identified using a self-report questionnaire (LTE-Q; List of Threatening Experiences Questionnaire: A subset of prescribed life events with considerable long-term contextual threat by T. Brugha, C. Bebbington, P. Tennant, and J. Hurry, 1985, Psychological Medicine, Vol. 15, pp. 189-194.) followed by a telephone interview. Only borderline personality pathology was related to an increase in the frequency of interpersonal stressful life events. Three specific symptoms of BPD were largely responsible for this connection: unstable interpersonal relationships, impulsivity, and chronic feelings of emptiness (negative association). Symptoms of avoidant and schizoid personality disorders were associated with a reduced number of stressful life events that are considered to be outside a person's control (e.g., serious illness, injury, or death of a loved one). None of the personality disorders predicted an increase in the number of