scholarly journals THE INFLUENCE OF RATE OF DAMAGE ACCUMULATION IS USED IN THE CALCULATION OF DUCTILITY RESOURCE

2019 ◽  
pp. 5-11
Author(s):  
Iryna Derevenko ◽  
Olena Solona
Keyword(s):  
Stress State ◽  
Metal Forming ◽  
Damage Accumulation ◽  
Accumulation Rate ◽  
Complex Loading ◽  
First Derivative ◽  
Marginal Change ◽  
History Of ◽  
Derivatives Of ◽  
Scalar Integral

In assessing marginal change in the process of metal forming, plasticity is significantly affected by the rate of damage accumulation and their healing as derivatives of the stress state indicators. It is shown that under complex loading conditions, when the damage accumulation rate (the first derivative of the stress state indicators) is more than 5 and the curvature of the material deformation trajectories (the second derivative of the stress state indicators) is greater than 1, the scalar integral criteria give the most reliable results destruction, taking into account the influence of the history of deformation on plasticity.

Hydrological changes in the Rzecin peatland (Puszcza Notecka, Poland) induced by anthropogenic factors: Implications for mire development and carbon sequestration

The Holocene ◽  
2016 ◽  
Vol 27 (5) ◽  
pp. 651-664 ◽  
Author(s):  
Krystyna Milecka ◽  
Grzegorz Kowalewski ◽  
Barbara Fiałkiewicz-Kozieł ◽  
Mariusz Gałka ◽  
Mariusz Lamentowicz ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Plant Communities ◽  
Human Activity ◽  
Accumulation Rate ◽  
Carbon Accumulation ◽  
Anthropogenic Factors ◽  
Poor Fen ◽  
History Of ◽  
Carbon Accumulation Rates

Wetlands are very vulnerable ecosystems and sensitive to changes in the ground water table. For the last few thousand years, hydrological balance has also been influenced by human activity. To improve their cropping features, drainage activity and fertilizing were applied. The drainage process led to an abrupt change of environment, the replacement of plant communities and the entire ecosystem. The problem of carbon sequestration is very important nowadays. A higher accumulation rate is related to higher carbon accumulation, but the intensity of carbon sequestration depends on the type of mire, habitat, and climatic zone. The main aim of this article was an examination of the changes in poor-fen ecosystem during the last 200 years in relation to natural and anthropogenic factors, using paleoecological methods (pollen and macrofossils). The second aim was a detailed investigation of the sedimentary record to aid our understanding of carbon sequestration in the poor fen of temperate zone. This case study shows that fens in temperate zones, in comparison with boreal ones, show higher carbon accumulation rates which have been especially intensive over the last few decades. To reconstruct vegetation changes, detailed palynological and macrofossil analyses were done. A 200-year history of the mire revealed that it was influenced by human activity to much degree. However, despite the nearby settlement and building of the drainage ditch, the precious species and plant communities still occur.

.VII. Contributions towards the history of the colouring matters derived from aniline

1863 ◽  
Vol 12 ◽  
pp. 645-647 ◽  
Keyword(s):  
Royal Society ◽  
Short Paper ◽  
Aromatic Diamines ◽  
History Of ◽  
Derivatives Of ◽  
Careful Comparison ◽  
Phenylene Diamine

In a short paper recently submitted to the Royal Society, I pointed out the existence of two aromatic diamines, both represented by the formula C 6 H 8 N 2 = (C 6 H 4 )'' H 2 H 2 } N 2 , and closely resembling each other, but differing in some of their fundamental characters to such an extent that I did not hesitate to assert their individuality, and to distinguish them as alpha-pheny-lene-diamine and beta-phenylene-diamine. The existence of two closely allied bodies among the diatomic derivatives of the phenyl-series very naturally suggested the idea of searching for two similarly related monatomic bases of the same group, and accordingly I undertook during the last week a careful comparison of specimens of aniline prepared by different piocesses. This com parative study is still incomplete, but I beg leave to record even now an observation which appears to merit the attention of chemists.

scholarly journals SEAMUS (v1.0): a Δ<sup>14</sup>C-enabled, single-specimen sediment accumulation simulator

2019 ◽  
Author(s):  
Bryan C. Lougheed
Keyword(s):  
Sediment Core ◽  
Accumulation Rate ◽  
Sediment Accumulation ◽  
Species Abundance ◽  
Depth Interval ◽  
Single Specimen ◽  
14C Dating ◽  
Deep Sea Sediment ◽  
Wide Range ◽  
History Of

Abstract. The systematic bioturbation of single particles (such as foraminifera) within deep-sea sediment archives leads to the apparent smoothing of any temporal signal as record by the downcore, discrete-depth mean signal. This smoothing is the result of the systematic mixing of particles from a wide range of depositional ages into the same discrete depth interval. Previous sediment models that simulate bioturbation have specifically produced an output in the form of a downcore, discrete-depth mean signal. Palaeoceanographers analysing the distribution of single foraminifera specimens from sediment core intervals would be assisted by a model that specifically evaluates the effect of bioturbation upon single specimen populations. Taking advantage of recent increases in computer memory, the single-specimen SEdiment AccuMUlation Simulator (SEAMUS) was created in Matlab, whereby large arrays of single specimens are simulated. This simulation allows researchers to analyse the post-bioturbation age heterogeneity of single specimens contained within discrete-depth sediment core intervals, and how this heterogeneity is influenced by changes in sediment accumulation rate (SAR), bioturbation depth (BD) and species abundance. The simulation also assigns a realistic 14C activity to each specimen, by considering the dynamic Δ14C history of the Earth and temporal changes in reservoir age. This approach allows for the quantification of possible significant artefacts arising when 14C dating multi-specimen samples with heterogeneous 14C activity. Users may also assign additional desired carrier signals to specimens (e.g., stable isotopes, trace elements, temperature, etc.) and consider a second species with an independent abundance. Finally, the model can simulate a virtual palaeoceanographer by randomly picking whole specimens (whereby the user can set the percentage of older, broken specimens) of a prescribed sample size from discrete depths, after which virtual laboratory 14C dating and 14C calibration is carried out within the model.

Fatigue Damage Accumulation under the Complex Varying Loading

2014 ◽  
Vol 617 ◽  
pp. 187-192 ◽  
Author(s):  
Boris Melnikov ◽  
Artem Semenov
Keyword(s):  
Damage Accumulation ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Hysteresis Loops ◽  
Fatigue Analysis ◽  
Wave Loads ◽  
Fatigue Damage Accumulation ◽  
History Of ◽  
Strain Stress ◽  
Irregular Loading

Fatigue analysis of steel parts of structures, which are subjected to complex irregular loading programs caused by wind, thermal, wave loads, earthquakes and combined imposed actions, requires in some cases using special methods of stress-strain evaluation. The model of the low cycle fatigue nonlinear damage accumulation is developed with taking into account the history of the deformation process. The damage is defined on the base of considering the quasi-static accumulation of maximal strain (stress) and hysteresis loops. The identification of material constants of the model is discussed. Application of the damage model for fatigue analysis of the antennas, pipelines, basements and fasteners units is considered and a comparison with experiments is given.

Analytical expressions for gravity anomalies due to homogeneous polyhedral bodies and translations into magnetic anomalies

Geophysics ◽  
1979 ◽  
Vol 44 (4) ◽  
pp. 730-741 ◽  
Author(s):  
M. Okabe
Keyword(s):  
Gravitational Potential ◽  
Computing Time ◽  
Gravity Anomalies ◽  
Magnetic Anomalies ◽  
Two Dimensions ◽  
First Derivative ◽  
Second Derivatives ◽  
Analytical Expressions ◽  
Derivatives Of ◽  
The Magnetic Field

Complete analytical expressions for the first and second derivatives of the gravitational potential in arbitrary directions due to a homogeneous polyhedral body composed of polygonal facets are developed, by applying the divergence theorem definitively. Not only finite but also infinite rectangular prisms then are treated. The gravity anomalies due to a uniform polygon are similarly described in two dimensions. The magnetic potential due to a uniformly magnetized body is directly derived from the first derivative of the gravitational potential in a given direction. The rule for translating the second derivative of the gravitational potential into the magnetic field component is also described. The necessary procedures for practical computer programming are discussed in detail, in order to avoid singularities and to save computing time.

scholarly journals Response times of ice-sheet surface heights to changes in the rate of Antarctic firn compaction caused by accumulation and temperature variations

2015 ◽  
Vol 61 (230) ◽  
pp. 1037-1047 ◽  
Author(s):  
Jun Li ◽  
H. Jay Zwally
Keyword(s):  
Response Times ◽  
Accumulation Rate ◽  
Meteorological Data ◽  
Climate Data ◽  
West Antarctica ◽  
Temperature Variations ◽  
Depth Profiles ◽  
Rates Of Change ◽  
Surface Weather ◽  
History Of

AbstractVariations in accumulation rate As(t) and temperature Ts(t) at the surface of firn cause changes in the rate of firn compaction (FC) and surface height H(t) that do not involve changes in mass, and therefore need to be accounted for in deriving mass changes from measured H(t). As the effects of changes in As(t) and Ts(t) propagate into the firn, the FC rate is affected with a highly variable and complex response time. The H(t) during measurement periods depend on the history of As(t) and Ts(t) prior to the measurements. Consequently, knowledge of firn response times to climate perturbations is important to estimate the required length of the time series of As(t) and Ts(t) used in FC models. We use our numerical FC model, which is time-dependent on both temperature and accumulation rate, to examine the response times of both H(t) and the rates of change dH(t)/dt to variations in As(t) and Ts(t) using sample perturbations and climate data for selected sites in Antarctica. Our results show that the response times for dH(t)/dt, which are of particular interest, are much shorter than the responses of H(t). Typical response times of dH(t)/dt are from several years to <20 years. The response times are faster in warmer and higher-accumulation areas such as Byrd Station, West Antarctica (4 years), and slower in colder and lower-accumulation areas such as Vostok, East Antarctica (18 years). The response times to temperature are much faster (0.9 year at Byrd and 2.2 years at Vostok), but the corresponding height changes persist much longer. The associated variations in firn density are significantly preserved in the density–depth profiles. For typical fluctuations of surface weather, the Ts(t) from satellite observations since 1982 and As(t) from meteorological data since 1979 are essentially of sufficient length to correct for FC height changes for measurements beginning in 1992.

Methods For Restoring and Describing Ancient Clinoform Surfaces

2018 ◽  
Vol 88 (2) ◽  
pp. 241-259 ◽  
Author(s):  
Tore Grane Klausen ◽  
William Helland-Hansen
Keyword(s):  
Depositional Environment ◽  
Sediment Load ◽  
Isostatic Compensation ◽  
Common Reference ◽  
Shelf Slope ◽  
History Of ◽  
Slope Sediment ◽  
Relative Change ◽  
Derivatives Of ◽  
3D Surfaces

Abstract Clinoform geometries demarcate a relative change from shallow to deeper waters and are therefore routinely used as paleogeography and paleobathymetry indicators. Distinct segments of the clinoform surface are defined based on their discrete breaks in slope, and these points define parameters which are used to describe and compare clinoform geometries from different basins and ages. In most cases, the breaks in slope are readily interpreted, but placement of the various breaks in slope remains mostly subjective and not strictly uniform. For clinoform geometries with gentle transitions and less accentuated breaks in slope, e.g., mud-prone systems, distinct breaks in slope can vary over many kilometers depending on selection criteria and detection method. The older and more complex history of the investigated strata, the harder it becomes to correctly place the different breaks in slope. This study proposes a common reference frame using an upper regional datum, in which the geometries of ancient clinoform surfaces can be restored. Restoration is performed with standard decompaction techniques, but we compare isostatic compensation using Airy isostasy with different scenarios of flexural support for the sediment load. Regression is used to fit a surface function to georeferenced points along the restored clinoform surface, and derivatives of this surface function are used to objectively and accurately describe and measure parameters such as relief, length, and gradient, in addition to numerically defining the bottomset, foreset, and topset segments of the clinoform surface. This enables comparison with modern counterparts unaltered by postdepositional subsidence and compaction, and the proposed procedure can be applied to 2D profiles from seismic, outcrop, or closely spaced well logs. It can also help in the analyses of 3D surfaces and the trajectory of discrete breaks in slope on successive clinoform surfaces. Accurate reconstructions and objective parameterization directly affect interpretation of shelf–slope sediment partitioning and depositional environment.

scholarly journals Ball Convergence of an Efficient Eighth Order Iterative Method Under Weak Conditions

Mathematics ◽  
2018 ◽  
Vol 6 (11) ◽  
pp. 260 ◽  
Author(s):  
Janak Sharma ◽  
Ioannis Argyros ◽  
Sunil Kumar
Keyword(s):  
Iterative Method ◽  
Iterative Methods ◽  
Higher Order ◽  
High Order ◽  
Convergence Order ◽  
Eighth Order ◽  
First Derivative ◽  
Ball Convergence ◽  
Derivatives Of

The convergence order of numerous iterative methods is obtained using derivatives of a higher order, although these derivatives are not involved in the methods. Therefore, these methods cannot be used to solve equations with functions that do not have such high-order derivatives, since their convergence is not guaranteed. The convergence in this paper is shown, relying only on the first derivative. That is how we expand the applicability of some popular methods.

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