perfect models
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Author(s):  
R. Lee Lyman

Despite years of graphing culture change using different types and styles of diagram, there is minimal discussion of graph grammar—how to construct an effective and efficient graph, and how to decipher a graph of change. Part of the difficulty attending graph decipherment resided in (and continues to reside in) unclear distinction of transformational change from variational change. Models reflecting the former tend to be commonsensical and are similar to Petrie’s classic sequence dating graphs. The difficulty of graph decipherment is exacerbated by parsing temporally continuous variation into discontinuous spatio-temporally bounded units known as artifact types, cultures, phases, periods, stages, etc. These units are reified and (implicitly) conceived as real entities to be discovered for want of a well-developed theory of change and an attendant ontology of how continuously variable phenomena should be parsed into types for analysis. Archaeologists did perfect models of diffusion—the movement of culture traits (ideas or norms manifest as artifact types) across space over time—and built models of how it should be reflected in the archaeological record. A majority of introductory archaeology textbooks published since 1965 typically present graphs of culture change in the form of a spindle graph but with minimal discussion of graph grammar. Texts on regional or continental prehistory typically summarize culture change in spatio-temporal rectangle diagrams, which for pedagogical reasons may be reasonable. A few spindle graphs have been published in other disciplines and, like archaeological spindles, display temporally shifting frequencies.


Author(s):  
V. G. Mikhailov

The purpose of the given work is consideration and working off of approaches, techniques, schemes of realisation of modelling of the vehicle on simulators on the basis of a choice of more perfect models of movement, fluctuations, roadability of the vehicle in package Matlab/Simulink for reception and an estimation of parametres of the vehicle, it loading. Features of imitating modelling of the vehicle on a simulator, requirements to it, using methods of such modelling on the basis of computer models, hydropulsators and a moving platform with the monitors/projectors, simulating road conditions where reactions to it of the driver, movements essentially influencing modes and loading the vehicle with the further use of the received data at bench tests are considered are considered. Mathematical models of the tyre, movement, fluctuations, the roadabilities of the vehicle providing more correct modelling in real time are developed.New approaches and technique in realisation of imitating modelling of movement, roadability and loading the vehicle, based on combined use of the powerful computer and minicomputer Raspberry for reading of parametres of controls, steering of visualisation of road conditions, module S-Function Builder created ON on С/C++ both an incorporated file longinal profile and a microprofile of real road, the information interchange organisation through three general files on SD disk Raspberry with certain periodicity (5 Hz) are offered, the block diagramme in Matlab/Simulink and is developed software. By the spent modelling of the vehicle 6х6 with ma = 21200 kg it is established that it has fuel consumption of km of 63,56 l/100, average speed of 66,1 km/h and number of switchings of a check point 7 (at t> 10 c). And basically check point switching occurs on last 3 higher drives.


2018 ◽  
Vol 24 (2) ◽  
pp. 108 ◽  
Author(s):  
Ayse Banu Demir ◽  
Namik Demir

<p>Monozygotic twins share the same genotype since they are derived from the same zygote. However, monozygotic (MZ) twin siblings frequently present many phenotypic differences, such as their susceptibilities to diseases. These isogenic individuals are not entirely identical. They exhibit phenotypic incompatibility for many features, from birth weight to complex diseases. Recently, several studies have been published showing that phenotypic differences, especially in MZ twins, are being induced from prenatal period to life-long epigenetic differences. Epigenetic studies on twins have a great potential to contribute to our understanding of complex diseases, such as cancer, autoimmune disorders, psychiatric disorders and neurological diseases. Since MZ twins are genetic clones (genetically identical), they are considered as perfect models for studying the role of environmental factors as determinants of complex diseases and phenotypes. In this review, a number of intrauterine effects and genetic mechanisms that may affect phenotypic, genotypic, and epigenetic differences between MZ twins were described and effects of epigenetic mechanisms on complex diseases were mentioned. Further work on epigenetic changes in diseases using incompatible MZ twin models, would lead to new developments in medical therapies.</p>


2014 ◽  
Vol 29 ◽  
pp. 93-104 ◽  
Author(s):  
Sadegh Imani Yengejeh ◽  
Seyedeh Alieh Kazemi ◽  
Andreas Öchsner

This study deals with the investigation of the tensile and shear behavior of connected carbon nanotubes (CNTs) with parallel longitudinal axes by performing several computational tests. In particular, the effect of imperfections on the mechanical properties, i.e. Young’s modulus and shear modulus, of these nanoconfigurations was analyzed. For this purpose, straight hetero-junctions were simulated in their perfect form and different boundary conditions were considered. In the second phase the three most likely atomic defects, i.e. impurities (doping with Si atoms), vacant sites (carbon vacancy) and introduced perturbations of the ideal geometry in different amounts to the perfect models, were simulated. Finally, the mechanical properties of imperfect hetero-junctions were numerically evaluated and compared with the behavior of perfect ones. It was concluded that the existence of any type of imperfections in the structure of connected CNTs leads to a reduction in the Young’s modulus as well as the shear modulus, and as a result, lower stiffness of these straight nanostructures.


2014 ◽  
Vol 06 (06) ◽  
pp. 1450077 ◽  
Author(s):  
SADEGH IMANI YENGEJEH ◽  
SEYEDEH ALIEH KAZEMI ◽  
ANDREAS ÖCHSNER

Connected carbon nanotubes (CNTs) with parallel longitudinal axes and with bending angles were simulated by a commercial finite element package and their buckling behavior was investigated by performing several computational examinations. In addition, the effect of defects on the structural stability of these heterojunctions was analyzed. For this purpose, two different nanotube hybrids (straight and kink heterojunction) were constructed in their perfect forms. In the second phase, three most likely atomic defects, i.e., impurities (doping with Si atoms), vacant sites (carbon vacancy) and introduced perturbations of the ideal geometry in different amounts to the perfect models, were simulated. To conclude our study, the buckling behavior of imperfect heterojunctions was numerically evaluated and compared with the behavior of the perfect ones. It was concluded that the existence of any type of defects in the configuration of nanotube hybrids leads to a lower critical load and as a result, lower buckling properties. This study provides a better insight into the prediction of straight and kink heterojunction CNTs behavior.


2014 ◽  
Vol 794-796 ◽  
pp. 63-67 ◽  
Author(s):  
Sigurd Wenner ◽  
Calin Daniel Marioara ◽  
Williams Lefebvre ◽  
Quentin M. Ramasse ◽  
Despoina Maria Kepaptsoglou ◽  
...  

The high-strength weldable 7xxxseries of aluminium alloys are of great importance to the aeronautics industry. Only recently, the complex structures of the AlZnMg hardening precipitates have been solved by HAADFSTEM imaging and first-principles calculations. However, perfect models of precipitate structures are often insufficient as several elements may be mixed into precipitate compositions. We have investigated this effect by STEMEELS spectrum imaging with an aberration-corrected microscope. In a 7449 alloy, Cu and Al were found to replace atoms at certain sites in both metastable and equilibrium ZnMg precipitates.


2013 ◽  
Vol 141 (6) ◽  
pp. 1786-1803 ◽  
Author(s):  
Ethan Atkins ◽  
Matthias Morzfeld ◽  
Alexandre J. Chorin

Abstract The implicit particle filter is a sequential Monte Carlo method for data assimilation that guides the particles to the high-probability regions via a sequence of steps that includes minimizations. A new and more general derivation of this approach is presented and the method is extended to particle smoothing as well as to data assimilation for perfect models. Minimizations required by implicit particle methods are shown to be similar to those that one encounters in variational data assimilation, and the connection of implicit particle methods with variational data assimilation is explored. In particular, it is argued that existing variational codes can be converted into implicit particle methods at a low additional cost, often yielding better estimates that are also equipped with quantitative measures of the uncertainty. A detailed example is presented.


1999 ◽  
Vol 31 (1) ◽  
pp. 25-65 ◽  
Author(s):  
C.A. Johnson
Keyword(s):  

1999 ◽  
Vol 39 (3) ◽  
pp. 249-258
Author(s):  
Sergey M. Dudakov

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