fractal characteristics
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2022 ◽  
pp. 1-46
Author(s):  
Peng Li ◽  
Zhongbao Liu ◽  
He Bi ◽  
Jun Liu ◽  
Min Zheng ◽  
...  

With the development of the global shale oil and gas revolution, shale oil became an important replacement field to increase oil and gas reserves and production. The Chang 7 Member of the Yanchang Formation in the Ordos Basin was an important shale oil exploration series in China. To study the micropore-throat structure characteristics of the Chang 7 Member, we launched nuclear magnetic resonance (NMR) and high-pressure mercury injection (HPMI) experiments to analyze the pore-throat structure features of the Chang 7 reservoir, and we considered fractal theory to study the fractal characteristics. The NMR results indicated that the T2 spectral morphology of the Chang 7 reservoir could be characterized by three main patterns encompassing early and late peaks with different amplitudes: the type 1 reservoir contained mostly small pores and few large pores, and the porosities of the small and large pores range from 4.16% to 9.04% and 0.70% to 2.40%, respectively. The type 2 reservoir contained similar amounts of small and large pores, and the type 3 reservoir contained few small pores and mostly large pores, while the porosities of the small and large pores range from 1.81% to 2.74% and 3.32% to 5.64%, respectively. The pore-throat structure parameters were obviously affected by the pore size distribution, which in turn influenced the reservoir seepage characteristics of the reservoir. The micropore-throat structure of the reservoir exhibited obvious piecewise fractal characteristics and mainly included dichotomous and trilateral fractals. The type 1 reservoirs were dominated by dichotomous fractals, and these two fractal types were equally distributed in the type 2 and 3 reservoirs. The fractal dimension of the pore throats of different scales exhibited a negative correlation with the corresponding porosity, but no correlation was observed with the permeability, indicating that the size of the reservoir determined by pore throats imposed a strong controlling effect on their fractal characteristics.


2022 ◽  
Vol 12 ◽  
Author(s):  
Xufen Xie ◽  
Chuanchuan Zhu ◽  
Di Wu ◽  
Ming Du

Naturally derived bioactive peptides with antihypertensive activities serve as promising alternatives to pharmaceutical drugs. There are few relevant reports on the mapping relationship between the EC50 value of antihypertensive peptide activity (AHTPA-EC50) and its corresponding amino acid sequence (AAS) at present. In this paper, we have constructed two group series based on sorting natural logarithm of AHTPA-EC50 or sorting its corresponding AAS encoding number. One group possesses two series, and we find that there must be a random number series in any group series. The random number series manifests fractal characteristics, and the constructed series of sorting natural logarithm of AHTPA-EC50 shows good autocorrelation characteristics. Therefore, two non-linear autoregressive models with exogenous input (NARXs) were established to describe the two series. A prediction method is further designed for AHTPA-EC50 prediction based on the proposed model. Two dynamic neural networks for NARXs (NARXNNs) are designed to verify the two series characteristics. Dipeptides and tripeptides are used to verify the proposed prediction method. The results show that the mean square error (MSE) of prediction is about 0.5589 for AHTPA-EC50 prediction when the classification of AAS is correct. The proposed method provides a solution for AHTPA-EC50 prediction.


2022 ◽  
pp. 104532
Author(s):  
Biao Kong ◽  
Zedong Zhuang ◽  
Xiaoying Zhang ◽  
Shun Jia ◽  
Wei Lu ◽  
...  

2021 ◽  
Vol 12 (1) ◽  
pp. 289
Author(s):  
Hongxing Han ◽  
Yun Ma ◽  
Wei He ◽  
Weifang Yang ◽  
Xudong Fu

With the use of the particle flow code in two dimensions, a fractal model is established with the number of particles of different particle fractions used as the statistics to study the fractal characteristics of particle size distribution. Numerically simulated specimens obtained by four scale methods are subjected to the relative density test and the biaxial compression test to explore the influences of fractal dimension D on the macroscopic and mesomechanical properties of specimens, as well as to study the relationship between fractal dimension D and different mechanical performance indexes. Results show that the particle size distribution of each of the four groups after scale exhibits fractal characteristics, with the fractal dimension D ranging from 1.27 to 2.03. The number of fine particles in the specimen increases with the fractal dimension D, the particle aggregates become more compact, the macroscopic mechanical properties of the specimens are improved, and a linear relationship exists between the fractal dimension D and different mechanical performance indexes. A large fractal dimension D corresponds to a great mesoparticle coordination number.


Author(s):  
Wangjian Cheng ◽  
Kun Li ◽  
Lilong Gao ◽  
Chenhe Feng ◽  
Chongwei An ◽  
...  

Author(s):  
Елена Михайловна Семенова ◽  
Марина Борисовна Ляхова ◽  
Дмитрий Викторович Иванов ◽  
Артем Игоревич Синкевич ◽  
Александр Сергеевич Антонов ◽  
...  

Методом атомно-силовой микроскопии получены изображения наноструктры составляющих гетерогенного интерметаллида SmCoCuFeZr в высококоэрцитивном состоянии. На микроуровне в сплавах выделили два типа областей (фазовых составляющих) отличающихся по интегральному элементному составу и интервалам коэрцитивности. На основе данных атомно-силового микроскопа проводится анализ фрактальных характеристик поверхности этих областей. Показано, что фрактальная размерность наноструктуры коррелирует с локальной коэрцитивностью фазовых составляющих. Фазовая составляющая с относительно низкой коэрцитивностью демонстрирует возможность существования структур с фрактальной размерностью в диапазоне 2,396 - 2,475, что соответствует умеренно развитому фрактальному рельефу. При этом высококоэрцитивная составляющая с регулярной наноструктурой характеризуется более высокой фрактальной размерностью 2,452 - 2,508, а на отдельных участках образца встречались области с фрактальной размерностью до 2,577 . The atomic force microscopy was used to obtain images of the nanostructure of components of a heterogeneous intermetallic SmCoCuFeZr compound in a highly coercive state. At the microlevel, two types of regions were distinguished in the alloys, differing in integral elemental composition and coercivity intervals. Based on the atomic force microscopy data, an analysis of the fractal characteristics of the surface is carried out on both of the above types of areas. It is shown that the fractal dimension of the nanostructure correlates with the local coercivity of the phase components. The phase component with a relatively low coercivity demonstrates the possibility of the existence of structures with fractal dimensions in the 2,396 - 2,475 range corresponding to a moderately developed fractal relief. In this case, the high-coercive component with a regular nanostructure is characterized by a higher fractal dimension of 2,452 - 2,508, and in some areas of the sample there were regions with a fractal dimension up to the value of 2,577.


Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Dayu Long ◽  
Changhong Li ◽  
Yu Wang ◽  
Yueqi Shi

This work is aimed at revealing the mesophysical process and mechanical behaviors of fine-grained tailing sand during seepage failure. The macroscopic seepage tests combined with posttest X-ray computed tomography (CT) were employed to study the fractal characteristics of mesostructure. Results show that before and after the seepage failure of fine-grained tailing sand, fractal of pore distribution ( D pd ) and fractal dimension of pore size ( D ps ) show a relatively obvious positive correlation with porosity. Tailing particles migrate along the seepage direction during the seepage process, resulting in the gradual decrease of D pd and pore distribution area. The D ps reflects the variation characteristics of pore number distribution with different pore sizes. The increase in D ps leads to a decrease in the uniformity of pore size and an increase in the size difference between pores. The mass fractal dimension ( D m ) of fine-grained tailing sand samples ranges from 1.6472 to 1.8256. With the increase of D m , the coefficient of uniformity ( C u ) of tailing sand tends to increase. The D m method can discern the seepage failure type of fine-grained tailing sand, and it is more accurate than the traditional method. This study provides a reference for the prevention and control of the seepage failure of tailing dam.


2021 ◽  
Vol 31 (16) ◽  
Author(s):  
Zhongyuan Zhao ◽  
Yongping Zhang

It is of great significance to study the three-dimensional financial system model based on the discrete fractional-order theory. In this paper, the Julia set of the three-dimensional discrete fractional-order financial model is identified to show its fractal characteristics. The sizes of the Julia sets need to be changed in some situations, so it is necessary to achieve control of the Julia sets. In combination with the characteristics of the model, two different controllers based on the fixed point are designed, and the control of the three-dimensional Julia sets is realized by adding the controllers into the model in different ways. Finally, the simulation graphs show that the controllers can effectively control the fractal behaviors.


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