Certification of Composite Aircraft Structures Under Impact, Fatigue and Environmental Conditions. Part 3. Environmental Effects on Compressive Strength.

Environmental conditions can have spatially complex effects on the dynamics of marine fish stocks that change across life-history stages. Yet the potential for non-stationary environmental effects across multiple dimensions, e.g. space and ontogeny, are rarely considered. In this study, we examined the evidence for spatial and ontogenetic non-stationary temperature effects on Pacific hake Merluccius productus biomass along the west coast of North America. Specifically, we used Bayesian additive models to estimate the effects of temperature on Pacific hake biomass distribution and whether the effects change across space or life-history stage. We found latitudinal differences in the effects of temperature on mature Pacific hake distribution (i.e. age 3 and older); warmer than average subsurface temperatures were associated with higher biomass north of Vancouver Island, but lower biomass offshore of Washington and southern Vancouver Island. In contrast, immature Pacific hake distribution (i.e. age 2) was better explained by a nonlinear temperature effect; cooler than average temperatures were associated with higher biomass coastwide. Together, our results suggest that Pacific hake distribution is driven by interactions between age composition and environmental conditions and highlight the importance of accounting for varying environmental effects across multiple dimensions.

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Separating damage from environmental effects affecting civil structures for near real-time damage detection

Structural Health Monitoring ◽

10.1177/1475921717722060 ◽

2017 ◽

Vol 17 (4) ◽

pp. 850-868 ◽

Cited By ~ 7

Author(s):

William Soo Lon Wah ◽

Yung-Tsang Chen ◽

Gethin Wyn Roberts ◽

Ahmed Elamin

Keyword(s):

Damage Detection ◽

Real Time ◽

Environmental Effects ◽

Environmental Conditions ◽

Principal Component ◽

Detection Methods ◽

Real Time Monitoring ◽

Civil Structures ◽

Data Set ◽

Wide Range

Analyzing changes in vibration properties (e.g. natural frequencies) of structures as a result of damage has been heavily used by researchers for damage detection of civil structures. These changes, however, are not only caused by damage of the structural components, but they are also affected by the varying environmental conditions the structures are faced with, such as the temperature change, which limits the use of most damage detection methods presented in the literature that did not account for these effects. In this article, a damage detection method capable of distinguishing between the effects of damage and of the changing environmental conditions affecting damage sensitivity features is proposed. This method eliminates the need to form the baseline of the undamaged structure using damage sensitivity features obtained from a wide range of environmental conditions, as conventionally has been done, and utilizes features from two extreme and opposite environmental conditions as baselines. To allow near real-time monitoring, subsequent measurements are added one at a time to the baseline to create new data sets. Principal component analysis is then introduced for processing each data set so that patterns can be extracted and damage can be distinguished from environmental effects. The proposed method is tested using a two-dimensional truss structure and validated using measurements from the Z24 Bridge which was monitored for nearly a year, with damage scenarios applied to it near the end of the monitoring period. The results demonstrate the robustness of the proposed method for damage detection under changing environmental conditions. The method also works despite the nonlinear effects produced by environmental conditions on damage sensitivity features. Moreover, since each measurement is allowed to be analyzed one at a time, near real-time monitoring is possible. Damage progression can also be given from the method which makes it advantageous for damage evolution monitoring.

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Differential strengths of molecular determinants guide environment specific mutational fates

10.1101/134569 ◽

2017 ◽

Cited By ~ 1

Author(s):

Rohan Dandage ◽

Rajesh Pandey ◽

Gopal Jayaraj ◽

Kausik Chakraborty

Keyword(s):

Protein Folding ◽

Molecular Evolution ◽

Protein Stability ◽

Environmental Effects ◽

Environmental Conditions ◽

Fitness Landscape ◽

Dependent Manner ◽

The Common ◽

Physical And Chemical ◽

Substrate Binding Protein

AbstractUnder the influence of selection pressures imposed by natural environments, organisms maintain competitive fitness through underlying molecular evolution of individual genes across the genome. For molecular evolution, how multiple interdependent molecular constraints play a role in determination of fitness under different environmental conditions is largely unknown. Here, using Deep Mutational Scanning (DMS), we quantitated empirical fitness of ∼2000 single site mutants of Gentamicin-resistant gene (GmR). This enabled a systematic investigation of effects of different physical and chemical environments on the fitness landscape of the gene. Molecular constraints of the fitness landscapes seem to bear differential strengths in an environment dependent manner. Among them, conformity of the identified directionalities of the environmental selection pressures with known effects of the environments on protein folding proves that along with substrate binding, protein stability is the common strong constraint of the fitness landscape. Our study thus provides mechanistic insights into the molecular constraints that allow accessibility of mutational fates in environment dependent manner.Author SummaryEnvironmental conditions play a central role in both organismal adaptations and underlying molecular evolution. Understanding of environmental effects on evolution of genotype is still lacking a depth of mechanistic insights needed to assist much needed ability to forecast mutational fates. Here, we address this issue by culminating high throughput mutational scanning using deep sequencing. This approach allowed comprehensive mechanistic investigation of environmental effects on molecular evolution. We monitored effects of various physical and chemical environments onto single site mutants of model antibiotic resistant gene. Alongside, to get mechanistic understanding, we identified multiple molecular constraints which contribute to various degrees in determining the resulting survivabilities of mutants. Across all tested environments, we find that along with substrate binding, protein stability stands out as the common strong constraints. Remarkable direct dependence of the environmental fitness effects on the type of environmental alteration of protein folding further proves that protein stability is the major constraint of the gene. So, our findings reveal that under the influence of environmental conditions, mutational fates are channeled by various degrees of strengths of underlying molecular constraints.

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What contributes to differences in phenotypic variation between generations?

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200030398 ◽

2009 ◽

Vol 2009 ◽

pp. 200-200

Author(s):

A Wolc ◽

I White ◽

M Lisowski ◽

W G Hill

Keyword(s):

Animal Model ◽

Environmental Effects ◽

Environmental Conditions ◽

Phenotypic Variation ◽

Variance Components ◽

Genetic Variance ◽

Phenotypic Variance ◽

Base Population ◽

Substantial Heterogeneity ◽

Over Time

Under the animal model genetic variance is estimated in the base population taking into account inbreeding and is otherwise assumed to remain unchanged over generations. In practice, phenotypic variation differs randomly or systematically over time. Intuitively, such changes would be attributed mostly to environmental effects, and so lower heritability would be expected when variation is inflated. Studies in dairy cattle show contradictory results (e.g. Boldman and Freeman, 1990). Laying hens are kept under environmental conditions intended to be constant, but show substantial heterogeneity in phenotypic variance (VP) over generations. The aim was to investigate how variance components change.

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A Study on Low Velocity Impact of Woven Glass/Phenolic Composite Laminates Considering Environmental Effects

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.1303 ◽

2005 ◽

Vol 297-300 ◽

pp. 1303-1308 ◽

Cited By ~ 2

Author(s):

Jae Hoon Kim ◽

Duck Hoi Kim ◽

Hu Shik Kim ◽

Byoung Jun Park

Keyword(s):

Compressive Strength ◽

Environmental Effects ◽

Impact Loading ◽

Composite Laminates ◽

Impact Damage ◽

Low Velocity Impact ◽

Low Velocity ◽

Internal Damage ◽

The Impact ◽

Phenolic Composite

The objectives of this study are to evaluate the internal damage and compressive residual strength of composite laminate by impact loading. To investigate the environmental effects, as-received and accelerated-aged glass/phenolic laminates are used. UT C-Scan is used to determine the impact damage characteristics and CAI tests are carried out to evaluate quantitatively the reduction of compressive strength by impact loading. The damage modes of the woven glass/phenolic laminates are evaluated. In the case of the accelerated-aged laminates, as aging time increases, initial failure energy and residual compressive strength decrease.

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Environmental effects on fracture resistant and biaxial fatigue design of aircraft structures

Engineering Fracture Mechanics ◽

10.1016/0013-7944(73)90044-1 ◽

1973 ◽

Vol 5 (3) ◽

pp. 627-645 ◽

Cited By ~ 2

Author(s):

U.G. Goransson ◽

D.D. Froerer

Keyword(s):

Environmental Effects ◽

Aircraft Structures ◽

Biaxial Fatigue ◽

Fatigue Design

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Developmental and Environmental Effects on Assimilate Partitioning in Canada Thistle (Cirsium arvense)

Weed Science ◽

10.1017/s004317450005699x ◽

1992 ◽

Vol 40 (1) ◽

pp. 79-85 ◽

Cited By ~ 25

Author(s):

Thomas Tworkoski

Keyword(s):

Environmental Effects ◽

Environmental Conditions ◽

Growth Stage ◽

Early Spring ◽

Field Conditions ◽

Cirsium Arvense ◽

Growth Chamber ◽

Assimilate Partitioning ◽

Canada Thistle ◽

Flower Bud

Under field conditions, more photoassimilate moved to roots of Canada thistle at the bolt than at the bud, flower, or postflower stages. Similarly, greater photoassimilate accumulated in roots of Canada thistle in the greenhouse at the rosette and bolt than at the flower bud stage. Growth chamber experiments indicated that environmental conditions typical of fall, and possibly early spring, favored photoassimilate movement to the root and superseded growth stage control of assimilate partitioning. Allocation of assimilate within the root was strongly influenced by growth stage, with most assimilate being utilized for growth at the rosette stage and for fructan reserves in bolt and flower bud stages.

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