The proposed thermo-mechanical fatigue test rig is based on a rotating bending machine and employs a high and a low temperature sources. This permits imposing thermal and mechanical loading at relatively high frequencies on a portion of a surface generatrix of a tubular specimen. Using this rig, a series of experiments was carried out on superalloy test specimens. These tests were conducted at various mechanical loadings with the temperature cycling between 600 and 1050°C in 10 seconds. The temperature distribution on the test specimen was measured under stabilized conditions and the same was calculated using a finite element code. Good correlation was found between the experimental and simulated temperature distributions. The thermal stress field, hence calculated, enables us to identify the critical crack initiation sites of the specimen and to calculate the applied thermo-mechanical cycle. In this way, an equivalent constant temperature can be defined and fatigue life has been predicted using isothermal fatigue results only.
{"title":"A New Technique for High Frequency Multiaxial Thermo-mechanical Fatigue Testing of Materials","authors":"R. Chieragatti, Florin Calin Paun","doi":"10.1520/STP15269S","DOIUrl":"https://doi.org/10.1520/STP15269S","url":null,"abstract":"The proposed thermo-mechanical fatigue test rig is based on a rotating bending machine and employs a high and a low temperature sources. This permits imposing thermal and mechanical loading at relatively high frequencies on a portion of a surface generatrix of a tubular specimen. Using this rig, a series of experiments was carried out on superalloy test specimens. These tests were conducted at various mechanical loadings with the temperature cycling between 600 and 1050°C in 10 seconds. The temperature distribution on the test specimen was measured under stabilized conditions and the same was calculated using a finite element code. Good correlation was found between the experimental and simulated temperature distributions. The thermal stress field, hence calculated, enables us to identify the critical crack initiation sites of the specimen and to calculate the applied thermo-mechanical cycle. In this way, an equivalent constant temperature can be defined and fatigue life has been predicted using isothermal fatigue results only.","PeriodicalId":8583,"journal":{"name":"ASTM special technical publications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75054635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The micromechanisms of fracture and fatigue crack growth are elucidated for a new class of damage-tolerant niobium aluminide Nb 3 Al-xTi intermetallics. Fatigue crack growth in alloys containing 10 and 25 at% Ti is shown to occur primarily by cleavage, while alloys containing ∼40 at% Ti are shown to exhibit similar fracture and fatigue crack growth behavior to ductile metals and their alloys. Slower elevated-temperature (750°C) crack growth rates in the Nb 3 Al-40Ti alloy are attributed largely to the effects of oxide-induced crack closure. The transition from cleavage fracture (in the Nb 3 Al-10Ti and Nb 3 Al-25Ti alloys) to ductile fracture in the Nb 3 Al-40Ti is correlated with the onset of significant levels of crack-tip plasticity, which is predicted using atomistic simulations.
{"title":"The Fracture and Fatigue Crack Growth Behavior of Forged Damage-Tolerant Niobium Aluminide Intermetallics","authors":"F. Ye, C. Mercer, D. Farkas, W. Soboyejo","doi":"10.1520/STP13409S","DOIUrl":"https://doi.org/10.1520/STP13409S","url":null,"abstract":"The micromechanisms of fracture and fatigue crack growth are elucidated for a new class of damage-tolerant niobium aluminide Nb 3 Al-xTi intermetallics. Fatigue crack growth in alloys containing 10 and 25 at% Ti is shown to occur primarily by cleavage, while alloys containing ∼40 at% Ti are shown to exhibit similar fracture and fatigue crack growth behavior to ductile metals and their alloys. Slower elevated-temperature (750°C) crack growth rates in the Nb 3 Al-40Ti alloy are attributed largely to the effects of oxide-induced crack closure. The transition from cleavage fracture (in the Nb 3 Al-10Ti and Nb 3 Al-25Ti alloys) to ductile fracture in the Nb 3 Al-40Ti is correlated with the onset of significant levels of crack-tip plasticity, which is predicted using atomistic simulations.","PeriodicalId":8583,"journal":{"name":"ASTM special technical publications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91544025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The estimation of regional risks due to multiple stressors is a frontier in environmental toxicology and risk assessment. We are conducting a regional scale ecological risk assessment of multiple stressors in the Willamette Valley, Oregon. The Willamette River drains an extensive agricultural area and forests of both the Coastal and Cascades mountains. The river also receives effluents from paper mills and urban wastewater treatment facilities. A major tributary of the Willamette is the McKenzie River. The McKenzie watershed, which extends into the Cascade Mountains, is extensively forested. Stressors in this watershed include alterations in the landscape due to the harvest of trees, the infrastructure required for the logging, modification of the river or stream banks, and inputs due to contamination by localized urban and non-point sources. We are using the relative risk model (RRM) for ecological risk assessment developed by Wiegers, Landis, and colleagues to combine multiple stressors and receptors in a regional context. The first step in the RRM process is the establishment of assessment endpoints for the particular area and the placement of the endpoints in the landscape. Next, the method involves the development of risk matrices that combine diverse stressors and habitats within the region with numerical ranks. We have broken the McKenzie and Willamette watershed study areas into 13 risk regions and have mapped the locations of the point sources and are incorporating land use data. Using a variety of documents we have established the assessment space and are developing criteria for ranking stressors and habitats. We have also initiated a 3-year field research activity to confirm the risk predictions within the main channel. The sampling sites correspond to the risk regions of the RRM. The sampling program will characterize the population density and structure of the fish assemblage and measuring the health of the individual fish.
{"title":"Design of a Relative Risk Model Regional-Scale Risk Assessment with Confirmational Sampling for the Willamette and McKenzie Rivers, Oregon","authors":"W. Landis, M. Luxon, Leo R. Bodensteiner","doi":"10.1520/STP14415S","DOIUrl":"https://doi.org/10.1520/STP14415S","url":null,"abstract":"The estimation of regional risks due to multiple stressors is a frontier in environmental toxicology and risk assessment. We are conducting a regional scale ecological risk assessment of multiple stressors in the Willamette Valley, Oregon. The Willamette River drains an extensive agricultural area and forests of both the Coastal and Cascades mountains. The river also receives effluents from paper mills and urban wastewater treatment facilities. A major tributary of the Willamette is the McKenzie River. The McKenzie watershed, which extends into the Cascade Mountains, is extensively forested. Stressors in this watershed include alterations in the landscape due to the harvest of trees, the infrastructure required for the logging, modification of the river or stream banks, and inputs due to contamination by localized urban and non-point sources. We are using the relative risk model (RRM) for ecological risk assessment developed by Wiegers, Landis, and colleagues to combine multiple stressors and receptors in a regional context. The first step in the RRM process is the establishment of assessment endpoints for the particular area and the placement of the endpoints in the landscape. Next, the method involves the development of risk matrices that combine diverse stressors and habitats within the region with numerical ranks. We have broken the McKenzie and Willamette watershed study areas into 13 risk regions and have mapped the locations of the point sources and are incorporating land use data. Using a variety of documents we have established the assessment space and are developing criteria for ranking stressors and habitats. We have also initiated a 3-year field research activity to confirm the risk predictions within the main channel. The sampling sites correspond to the risk regions of the RRM. The sampling program will characterize the population density and structure of the fish assemblage and measuring the health of the individual fish.","PeriodicalId":8583,"journal":{"name":"ASTM special technical publications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84755359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Nondestructive evaluation of dimension stone using impulse-generated stress waves: Part 2 - Estimation of complex moduli","authors":"H. Reis, Amin K. Habboub","doi":"10.1520/STP13537S","DOIUrl":"https://doi.org/10.1520/STP13537S","url":null,"abstract":"","PeriodicalId":8583,"journal":{"name":"ASTM special technical publications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83100378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper provides a framework for evaluating risks in Indian Country. All cultures depend on environmental quality for their survival, but the health of tribal communities and their individual members is so intertwined with their environment as to be inseparable. The foundation of risk assessment, characterization, and management in Indian Country rests on the federal trust responsibility to protect the people, their homelands, and their natural and cultural resources. Thus, tribal risk assessments must include the probabilities of adverse health, ecological, and cultural impacts in order to be relevant to the affected tribal community and government. This paper presents several environmentally-focused methods for evaluating overall tribal community health risk and eco-cultural health impacts. Elements of this environmentally-based risk assessment include a culturally-sensitive human exposure scenario, ecological risk assessment that includes species of cultural concern, the evaluation of impacts to environmental functions and services, measurement of impacts to socioeconomic and sociocultural health, and a risk characterization step that combines of all these risks and impacts in a way that tells the whole story about impacts to the place or resource from the community's trusteeship perspectives. While these elements are likely to be common to most tribal risk assessments, it must also be recognized that each tribe's ecology, history, culture, and government are unique, so every tribal risk assessment will be unique. Several ways to evaluate tribal community health and eco-cultural risk are presented that include environmental functions and services, sociocultural and socioeconomic health impact measurement, and risk characterization. It is hoped that by presenting some initial methods for characterizing and comparing risks that are relevant to tribal cultures and communities an interdisciplinary discussion will be sparked that brings together the disciplines of social impact assessment, comparative risk (quality of life), natural resource valuation, public health, and conventional toxicity-based risk assessment.
{"title":"Measuring Risks to Tribal Community Health and Culture","authors":"B. Harper, Stuart G. Harris","doi":"10.1520/STP14423S","DOIUrl":"https://doi.org/10.1520/STP14423S","url":null,"abstract":"This paper provides a framework for evaluating risks in Indian Country. All cultures depend on environmental quality for their survival, but the health of tribal communities and their individual members is so intertwined with their environment as to be inseparable. The foundation of risk assessment, characterization, and management in Indian Country rests on the federal trust responsibility to protect the people, their homelands, and their natural and cultural resources. Thus, tribal risk assessments must include the probabilities of adverse health, ecological, and cultural impacts in order to be relevant to the affected tribal community and government. This paper presents several environmentally-focused methods for evaluating overall tribal community health risk and eco-cultural health impacts. Elements of this environmentally-based risk assessment include a culturally-sensitive human exposure scenario, ecological risk assessment that includes species of cultural concern, the evaluation of impacts to environmental functions and services, measurement of impacts to socioeconomic and sociocultural health, and a risk characterization step that combines of all these risks and impacts in a way that tells the whole story about impacts to the place or resource from the community's trusteeship perspectives. While these elements are likely to be common to most tribal risk assessments, it must also be recognized that each tribe's ecology, history, culture, and government are unique, so every tribal risk assessment will be unique. Several ways to evaluate tribal community health and eco-cultural risk are presented that include environmental functions and services, sociocultural and socioeconomic health impact measurement, and risk characterization. It is hoped that by presenting some initial methods for characterizing and comparing risks that are relevant to tribal cultures and communities an interdisciplinary discussion will be sparked that brings together the disciplines of social impact assessment, comparative risk (quality of life), natural resource valuation, public health, and conventional toxicity-based risk assessment.","PeriodicalId":8583,"journal":{"name":"ASTM special technical publications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81767083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes the thermo-mechanical fatigue behavior of Al-Si-Cu-Mg casting alloy. The alloy is widely used for cylinder heads and pistons of automobile engines. Repeated cycling between driving and resting, or low-power and high-power driving cause thermal cycling in the engine materials. The thermo-mechanical fatigue property is therefore very important to develop high-performance engines. This study aims to characterize the cyclic stress-strain behavior of this alloy and to clarify the factors dominating the fracture life. Results obtained are : (1) The stress-strain behavior changes remarkably during thermal cycling. Cyclic hardening and cycling softening occur in the higher and lower strain ranges, respectively. (2) A thermo-mechanical fatigue fracture limit diagram is obtained by connecting fracture points on the inelastic strain range - number of cycles relationship. (3) Consequently, in 10 3 - 10 4 cycles, it is considered that poor ductility and inelastic strain increase due to overaging dominate the thermo-mechanical fatigue life of the alloy.
{"title":"Thermo-mechanical Fatigue Behavior of Al-Si-Cu-Mg Casting Alloy","authors":"H. Ikuno, Shogo Iwanaga, Y. Awano","doi":"10.1520/STP15258S","DOIUrl":"https://doi.org/10.1520/STP15258S","url":null,"abstract":"This paper describes the thermo-mechanical fatigue behavior of Al-Si-Cu-Mg casting alloy. The alloy is widely used for cylinder heads and pistons of automobile engines. Repeated cycling between driving and resting, or low-power and high-power driving cause thermal cycling in the engine materials. The thermo-mechanical fatigue property is therefore very important to develop high-performance engines. This study aims to characterize the cyclic stress-strain behavior of this alloy and to clarify the factors dominating the fracture life. Results obtained are : (1) The stress-strain behavior changes remarkably during thermal cycling. Cyclic hardening and cycling softening occur in the higher and lower strain ranges, respectively. (2) A thermo-mechanical fatigue fracture limit diagram is obtained by connecting fracture points on the inelastic strain range - number of cycles relationship. (3) Consequently, in 10 3 - 10 4 cycles, it is considered that poor ductility and inelastic strain increase due to overaging dominate the thermo-mechanical fatigue life of the alloy.","PeriodicalId":8583,"journal":{"name":"ASTM special technical publications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89234680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. M. Agrawal, J. S. McKinney, Dingyi Huang, K. Athanasiou
{"title":"The use of the vibrating particle technique to fabricate highly porous and permeable biodegradable scaffolds","authors":"C. M. Agrawal, J. S. McKinney, Dingyi Huang, K. Athanasiou","doi":"10.1520/STP15303S","DOIUrl":"https://doi.org/10.1520/STP15303S","url":null,"abstract":"","PeriodicalId":8583,"journal":{"name":"ASTM special technical publications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86647566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many components are exposed to high thermal and mechanical loadings. For example, the blades of gas turbines are subjected to thermally and mechanically induced strains and stresses at varying temperatures. The former arise from inhomogeneous temperature fields, which are due to start-stop cycles, resulting in thermal fatigue. The latter arise from centrifugal forces, which arise from the rotation of the turbine, resulting in mechanical low cycle fatigue and creep during service. The combination of thermally induced loading and mechanically induced loading can neither be investigated in a conventional (strain controlled) thermal-mechanical fatigue (TMF) test nor in a conventional (stress controlled) creep test. Also the interaction between different volume elements within a component can not be investigated in a single specimen experiment. To simulate such "complex" thermal-mechanical fatigue loading, a two-specimen testing system was build up. At this testing system the thermal-mechanical loading of the specimens, each of them representing a distinct volume element of a component, is generated just by varying the temperature-time history of the two specimens and the coupling conditions between them. Furthermore, it is possible to superimpose an external force, e.g. representing the centrifugal force. The distribution of this force on the two specimens and the resulting deformation behaviour are the result of the interaction of the two specimens. The testing and interpretation methods as well as the results of first experiments with a 12% chromium steel and a 316 type stainless steel are presented.
{"title":"Realization of complex thermal-mechanical fatigue by a two-specimen testing system","authors":"L. Angarita, G. Pitz, K. Lang, D. Löhe","doi":"10.1520/STP15268S","DOIUrl":"https://doi.org/10.1520/STP15268S","url":null,"abstract":"Many components are exposed to high thermal and mechanical loadings. For example, the blades of gas turbines are subjected to thermally and mechanically induced strains and stresses at varying temperatures. The former arise from inhomogeneous temperature fields, which are due to start-stop cycles, resulting in thermal fatigue. The latter arise from centrifugal forces, which arise from the rotation of the turbine, resulting in mechanical low cycle fatigue and creep during service. The combination of thermally induced loading and mechanically induced loading can neither be investigated in a conventional (strain controlled) thermal-mechanical fatigue (TMF) test nor in a conventional (stress controlled) creep test. Also the interaction between different volume elements within a component can not be investigated in a single specimen experiment. To simulate such \"complex\" thermal-mechanical fatigue loading, a two-specimen testing system was build up. At this testing system the thermal-mechanical loading of the specimens, each of them representing a distinct volume element of a component, is generated just by varying the temperature-time history of the two specimens and the coupling conditions between them. Furthermore, it is possible to superimpose an external force, e.g. representing the centrifugal force. The distribution of this force on the two specimens and the resulting deformation behaviour are the result of the interaction of the two specimens. The testing and interpretation methods as well as the results of first experiments with a 12% chromium steel and a 316 type stainless steel are presented.","PeriodicalId":8583,"journal":{"name":"ASTM special technical publications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77801117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Total Strain Version of the method of Strainrange Partitioning was used as the basis for modeling the thermomechanical fatigue resistance of the matrix material of the metal matrix composite, SCS-6/Ti-15-3. As prescribed by the model, the resistance was assessed through the use of bithermal creep-fatigue experiments. Bithermal temperatures of 205 and 427°C were imposed. A minimal number of strain limit-controlled, in-phase PP (pure fatigue, no creep) and CP (tensile creep) as well as out-of-phase PP (pure fatigue, no creep) and PC (compressive creep) experiments were conducted on conventional, axially-loaded, cylindrical-bar specimens. Inelastic strain range versus cyclic life curves for each of the Strainrange Partitioning bithermal cycles were evaluated and found to be nominally coincident. Cyclic elastic strain range versus inelastic strain range curves as well as elastic strain range versus life curves were documented for pure-fatigue and creep-fatigue conditions. The time-dependencies of these relationships were calibrated with the available data. These results enable the construction of total strain range versus fatigue life curves for thermomechanical fatigue for in- and out-of-phasing and for any arbitrary creep-time per cycle. Results are applicable to the cyclic life prediction of metal matrix composites using the Ti-15-3 matrix material.
{"title":"Thermal Strain Fatigue Modeling of a Matrix Alloy for a Metal Matrix Composite","authors":"G. Halford, B. Lerch, V. K. Arya","doi":"10.1520/STP15261S","DOIUrl":"https://doi.org/10.1520/STP15261S","url":null,"abstract":"The Total Strain Version of the method of Strainrange Partitioning was used as the basis for modeling the thermomechanical fatigue resistance of the matrix material of the metal matrix composite, SCS-6/Ti-15-3. As prescribed by the model, the resistance was assessed through the use of bithermal creep-fatigue experiments. Bithermal temperatures of 205 and 427°C were imposed. A minimal number of strain limit-controlled, in-phase PP (pure fatigue, no creep) and CP (tensile creep) as well as out-of-phase PP (pure fatigue, no creep) and PC (compressive creep) experiments were conducted on conventional, axially-loaded, cylindrical-bar specimens. Inelastic strain range versus cyclic life curves for each of the Strainrange Partitioning bithermal cycles were evaluated and found to be nominally coincident. Cyclic elastic strain range versus inelastic strain range curves as well as elastic strain range versus life curves were documented for pure-fatigue and creep-fatigue conditions. The time-dependencies of these relationships were calibrated with the available data. These results enable the construction of total strain range versus fatigue life curves for thermomechanical fatigue for in- and out-of-phasing and for any arbitrary creep-time per cycle. Results are applicable to the cyclic life prediction of metal matrix composites using the Ti-15-3 matrix material.","PeriodicalId":8583,"journal":{"name":"ASTM special technical publications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89462859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Geotechnics of High Water Content Materials","authors":"R. Krizek","doi":"10.1520/STP14356S","DOIUrl":"https://doi.org/10.1520/STP14356S","url":null,"abstract":"","PeriodicalId":8583,"journal":{"name":"ASTM special technical publications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89486317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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