scholarly journals An algebro-geometric model for the shape of supercoiled DNA

2021 ◽  
pp. 133073
Author(s):  
Shigeki Matsutani ◽  
Emma Previato
2019 ◽  
pp. 40-47
Author(s):  
E. A. Mironchik

The article discusses the method of solving the task 18 on the Unified State Examination in Informatics (Russian EGE). The main idea of the method is to write the conditions of the problem utilizing the language of formal logic, using elementary predicates. According to the laws of logic the resulting complex logical expression would be transformed into an expression, according to which a geometric model is supposed to be constructed which allows to obtain an answer. The described algorithm does allow high complexity problem to be converted into a simple one.


Author(s):  
Т. В. Самодурова ◽  
О. В. Гладышева ◽  
Н. Ю. Алимова ◽  
Е. А. Бончева

Постановка задачи. Рассмотрена задача моделирования отложения снега во время метелей на автомагистралях с барьерными ограждениями в программе FlowVision . Результаты. В качестве опытного участка рассмотрен участок автомагистрали, проходящий в насыпи. Создана геометрическая модель участка автомагистрали. Обоснованы информационные ресурсы для создания гидродинамической модели обтекания насыпи автомагистрали с барьерными ограждениями снеговетровым потоком во время метелей. Проведено моделирование процесса снегонакопления на опытном участке с использованием программного комплекса FlowVision во время метелей с различными параметрами. Выводы. Сделан вывод о возможности применения программного комплекса FlowVision для совершенствования методики назначения снегозащитных устройств и определения параметров снегоочистки при зимнем содержании автомобильных дорог. Statement of the problem. The problems of snow deposit modeling on the highways with crash barriers during blizzards in the FlowVision was discussed. Results. The highway section passing in the embankment as an experimental section has been considered. The geometric model of the highway section was created. The information resources for designing a hydrodynamic model of a snowflow stream of highway embankment with barriers during blizzard were identified. The modeling of the snow deposit process in the experimental section using the FlowVision software during blizzards with different parameters was carried out. Conclusions. It was concluded that it is possible to use the FlowVision software to improve the methodology for snow protection designing and determining snow removal parameters for winter road maintenance.


2019 ◽  
pp. 32-35
Author(s):  
V. V. Artyushenko ◽  
A. V. Nikulin

In this article we consider a problem of reliable modeling of echo signals and angle noise of distributed objects using twodimensional geometric models with random statistically unrelated signals. The conditions that ensure the invariance of distribution parameters of the angle noise generated by an arbitrary N-point configuration of a two-dimensional geometric model are obtained. In the particular case of a model whose emitters are supplied with signals of equal power, the conditions of invariance are reduced to the location of the model points on the plane in the form of a regular polygon. These results can be used to synthesize mathematical models used for simulating reflections from distributed objects and for developing a hardware-software complex for the simulation of electromagnetic fields reflected from the Earth surface, atmospheric inhomogeneities, the sea surface, etc.


2015 ◽  
Vol 12 (19) ◽  
pp. 5871-5883 ◽  
Author(s):  
L. A. Melbourne ◽  
J. Griffin ◽  
D. N. Schmidt ◽  
E. J. Rayfield

Abstract. Coralline algae are important habitat formers found on all rocky shores. While the impact of future ocean acidification on the physiological performance of the species has been well studied, little research has focused on potential changes in structural integrity in response to climate change. A previous study using 2-D Finite Element Analysis (FEA) suggested increased vulnerability to fracture (by wave action or boring) in algae grown under high CO2 conditions. To assess how realistically 2-D simplified models represent structural performance, a series of increasingly biologically accurate 3-D FE models that represent different aspects of coralline algal growth were developed. Simplified geometric 3-D models of the genus Lithothamnion were compared to models created from computed tomography (CT) scan data of the same genus. The biologically accurate model and the simplified geometric model representing individual cells had similar average stresses and stress distributions, emphasising the importance of the cell walls in dissipating the stress throughout the structure. In contrast models without the accurate representation of the cell geometry resulted in larger stress and strain results. Our more complex 3-D model reiterated the potential of climate change to diminish the structural integrity of the organism. This suggests that under future environmental conditions the weakening of the coralline algal skeleton along with increased external pressures (wave and bioerosion) may negatively influence the ability for coralline algae to maintain a habitat able to sustain high levels of biodiversity.


2015 ◽  
Vol 741 ◽  
pp. 133-137
Author(s):  
Xian Zhao Jia ◽  
Yong Fei Wang

To ensure wheel body of the hoisting sheave strength and stability condition. For the purpose of wheel body lightweighting. There are two schemes to reduce body weight.Reduce the spokes at the same time increase the ring stiffened plate, and reduce the spokes at the same time change the spokes width and thickness.The wheel body was established based on Pro/E 3D geometric model. Import the mesh in the Workbench of ANSYS software for finite element model. Statics analysis to select the optimized scheme. Establish a hoisting sheave wheel body under the actual working condition of widening the width - deformation - wheel weight relational table. Analysis to lightweight at the same time ensure that stiffness of wheel,then it can obtaine the optimal result.


Author(s):  
Annika Niemann ◽  
Samuel Voß ◽  
Riikka Tulamo ◽  
Simon Weigand ◽  
Bernhard Preim ◽  
...  

Abstract Purpose For the evaluation and rupture risk assessment of intracranial aneurysms, clinical, morphological and hemodynamic parameters are analyzed. The reliability of intracranial hemodynamic simulations strongly depends on the underlying models. Due to the missing information about the intracranial vessel wall, the patient-specific wall thickness is often neglected as well as the specific physiological and pathological properties of the vessel wall. Methods In this work, we present a model for structural simulations with patient-specific wall thickness including different tissue types based on postmortem histologic image data. Images of histologic 2D slices from intracranial aneurysms were manually segmented in nine tissue classes. After virtual inflation, they were combined into 3D models. This approach yields multiple 3D models of the inner and outer wall and different tissue parts as a prerequisite for subsequent simulations. Result We presented a pipeline to generate 3D models of aneurysms with respect to the different tissue textures occurring in the wall. First experiments show that including the variance of the tissue in the structural simulation affect the simulation result. Especially at the interfaces between neighboring tissue classes, the larger influence of stiffer components on the stability equilibrium became obvious. Conclusion The presented approach enables the creation of a geometric model with differentiated wall tissue. This information can be used for different applications, like hemodynamic simulations, to increase the modeling accuracy.


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