Experimentally Derived Nearest-Neighbor Parameters for the Stability of RNA Three- and Four-Way Multibranch Loops†

Biochemistry ◽  
2002 ◽  
Vol 41 (3) ◽  
pp. 869-880 ◽  
Author(s):  
David H. Mathews ◽  
Douglas H. Turner
Keyword(s):  
Nearest Neighbor ◽  
The Stability ◽  
Multibranch Loops

Stability and Hopf Bifurcation of Nearest-Neighbor Coupled Neural Networks With Delays

2020 ◽  
Vol 15 (11) ◽  
Author(s):  
Lu Wang ◽  
Min Xiao ◽  
Shuai Zhou ◽  
Yurong Song ◽  
Jinde Cao
Keyword(s):  
Neural Networks ◽  
Hopf Bifurcation ◽  
Nearest Neighbor ◽  
Multiple Delays ◽  
Dimensional System ◽  
Practical Applications ◽  
Coupled Neural Networks ◽  
The Stability ◽  
Related Characteristic ◽  
Theoretical Analyses

Abstract In this paper, a high-dimensional system of nearest-neighbor coupled neural networks with multiple delays is proposed. Nowadays, most present researches about neural networks have studied the connection between adjacent nodes. However, in practical applications, neural networks are extremely complicated. This paper further considers that there are still connection relationships between nonadjacent nodes, which reflect the intrinsic characteristics of neural networks more accurately because of the complexity of its topology. The influences of multiple delays on the local stability and Hopf bifurcation of the system are explored by selecting the sum of delays as bifurcation parameter and discussing the related characteristic equations. It is found that the dynamic behaviors of the system depend on the critical value of bifurcation. In addition, the conditions that ensure the stability of the system and the criteria of Hopf bifurcation are given. Finally, the correctness of the theoretical analyses is verified by numerical simulation.

scholarly journals Laws and Trends of the Evolution of Traditional Villages in Plane Pattern

2020 ◽  
Vol 12 (7) ◽  
pp. 3005
Author(s):  
Xi Yang ◽  
Ke Song ◽  
Fuan Pu
Keyword(s):  
Spatial Data ◽  
Nearest Neighbor ◽  
Morphological Evolution ◽  
Temporal Analysis ◽  
Mean Value ◽  
Significant Shift ◽  
Spatial Processes ◽  
Common Mean ◽  
Multi Temporal ◽  
The Stability

This study collected and analyzed dynamic spatial data of eight traditional villages scattered in different regions of China. A multi-temporal analysis of morphological metrics of spatial patterns and a regression analysis of the morphological evolution were used to analyze and contrast the historical spatial processes of different villages. These were then compared using patch texture and rural macro-morphology perspectives. This led to an assessment of the general laws and trends associated with rural spatial processes. (1) There has been a significant shift in the stability of rural spatial development since the founding of the People’s Republic of China (PRC). (2) Most small and medium-sized villages have maintained a relatively stable spatial texture, while large villages have changed significantly. (3) The mean and variance of the patch area, and the Euclidean nearest-neighbor distance, are correlated in some cases. (4) The mode of rural expansion may be relevant to limitations in the total area of growth. (5) The fractal dimension of the rural macro-morphology may follow a morphological order of oscillation around the equilibrium level. (6) The common mean value of the projected area of rural building patches is expected to be 100 m2.

scholarly journals Evaluating the Stability of Embedding-based Word Similarities

2018 ◽  
Vol 6 ◽  
pp. 107-119 ◽  
Author(s):  
Maria Antoniak ◽  
David Mimno
Keyword(s):  
Nearest Neighbor ◽  
Word Embeddings ◽  
Training Set ◽  
Word Associations ◽  
Training Corpus ◽  
Study Word ◽  
Highly Sensitive ◽  
The Stability ◽  
Nearest Neighbor Distances

Word embeddings are increasingly being used as a tool to study word associations in specific corpora. However, it is unclear whether such embeddings reflect enduring properties of language or if they are sensitive to inconsequential variations in the source documents. We find that nearest-neighbor distances are highly sensitive to small changes in the training corpus for a variety of algorithms. For all methods, including specific documents in the training set can result in substantial variations. We show that these effects are more prominent for smaller training corpora. We recommend that users never rely on single embedding models for distance calculations, but rather average over multiple bootstrap samples, especially for small corpora.

scholarly journals Fault Diagnosis Method for Rolling Bearings Based on Composite Multiscale Fluctuation Dispersion Entropy

Entropy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 290 ◽  
Author(s):  
Xiong Gan ◽  
Hong Lu ◽  
Guangyou Yang
Keyword(s):  
Fault Diagnosis ◽  
Nearest Neighbor ◽  
Coarse Grained ◽  
K Nearest Neighbor ◽  
Rolling Bearings ◽  
Entropy Estimation ◽  
Fault Recognition ◽  
Knn Classifier ◽  
Diagnosis Method ◽  
The Stability

This paper proposes a new method named composite multiscale fluctuation dispersion entropy (CMFDE), which measures the complexity of time series under different scale factors and synthesizes the information of multiple coarse-grained sequences. A simulation validates that CMFDE could improve the stability of entropy estimation. Meanwhile, a fault recognition method for rolling bearings based on CMFDE, the minimum redundancy maximum relevancy (mRMR) method, and the k nearest neighbor (kNN) classifier (CMFDE-mRMR-kNN) is developed. For the CMFDE-mRMR-kNN method, the CMFDE method is introduced to extract the fault characteristics of the rolling bearings. Then, the sensitive features are obtained by utilizing the mRMR method. Finally, the kNN classifier is used to recognize the different conditions of the rolling bearings. The effectiveness of the proposed CMFDE-mRMR-kNN method is verified by analyzing the standard experimental dataset. The experimental results show that the proposed fault diagnosis method can effectively classify the conditions of rolling bearings.

scholarly journals Settling the matter of the role of vibrations in the stability of high-entropy carbides

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marco Esters ◽  
Corey Oses ◽  
David Hicks ◽  
Michael J. Mehl ◽  
Michal Jahnátek ◽  
...  
Keyword(s):  
Chemical Stability ◽  
Nearest Neighbor ◽  
Configurational Entropy ◽  
New Materials ◽  
Decomposition Products ◽  
Thermodynamic Characterization ◽  
High Entropy ◽  
Significant Interest ◽  
The Stability

AbstractHigh-entropy ceramics are attracting significant interest due to their exceptional chemical stability and physical properties. While configurational entropy descriptors have been successfully implemented to predict their formation and even to discover new materials, the contribution of vibrations to their stability has been contentious. This work unravels the issue by computationally integrating disorder parameterization, phonon modeling, and thermodynamic characterization. Three recently synthesized carbides are used as a testbed: (HfNbTaTiV)C, (HfNbTaTiW)C, and (HfNbTaTiZr)C. It is found that vibrational contributions should not be neglected when precursors or decomposition products have different nearest-neighbor environments from the high-entropy carbide.

scholarly journals Machine-Learning-Based Classification Approaches toward Recognizing Slope Stability Failure

2019 ◽  
Vol 9 (21) ◽  
pp. 4638 ◽  
Author(s):  
Moayedi ◽  
Bui ◽  
Kalantar ◽  
Foong
Keyword(s):  
Machine Learning ◽  
Slope Stability ◽  
Nearest Neighbor ◽  
Support Vector ◽  
Sequential Minimal Optimization ◽  
Stability Assessment ◽  
K Nearest Neighbor ◽  
The Stability ◽  
Intelligent Models ◽  
Improved Support Vector Machine

In this paper, the authors investigated the applicability of combining machine-learning-based models toward slope stability assessment. To do this, several well-known machine-learning-based methods, namely multiple linear regression (MLR), multi-layer perceptron (MLP), radial basis function regression (RBFR), improved support vector machine using sequential minimal optimization algorithm (SMO-SVM), lazy k-nearest neighbor (IBK), random forest (RF), and random tree (RT), were selected to evaluate the stability of a slope through estimating the factor of safety (FOS). In the following, a comparative classification was carried out based on the five stability categories. Based on the respective values of total scores (the summation of scores obtained for the training and testing stages) of 15, 35, 48, 15, 50, 60, and 57, acquired for MLR, MLP, RBFR, SMO-SVM, IBK, RF, and RT, respectively, it was concluded that RF outperformed other intelligent models. The results of statistical indexes also prove the excellent prediction from the optimized structure of the ANN and RF techniques.

Atomic Interactions and the Stability of Surface Clusters

1998 ◽  
Vol 528 ◽  
Author(s):  
Seong Jin Koh ◽  
Gert Ehrlich
Keyword(s):  
Simple Model ◽  
Nearest Neighbor ◽  
Equilibrium Shape ◽  
Model System ◽  
Palladium Clusters ◽  
Atomic Interactions ◽  
Surface Yield ◽  
Simple Model System ◽  
The Stability ◽  
Field Ion Microscope

AbstractInteractions dictating the shape and stability of surface islands have been examined for a simple model system, palladium clusters on the W(110) plane. Observations in a field ion microscope of the distribution of two Pd adatoms over the surface yield quantitative values for pair interactions. These are found to be complex, extending over distances longer than 10 A and to vary strongly with the orientation of the pair axis on the (110) surface. Using the measured pair energies it has been possible to infer the magnitude of many-atom effects necessary to account for the equilibrium shape of the clusters. Many-atom interactions turn out to make by far the largest contribution to cluster cohesion; modeling of growth phenomena in terms of nearest-neighbor bonds only is clearly problematic.

scholarly journals Computational Modeling Predicts the Stability of Both Pd+ and Pd2+ Ion-Exchanged into H-CHA

2020 ◽  
Author(s):  
Jeroen Van der Mynsbrugge ◽  
Martin Head-Gordon ◽  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Nearest Neighbor ◽  
Operating Conditions ◽  
Oxidation States ◽  
Vehicle Exhaust ◽  
Reducing Conditions ◽  
Wide Range ◽  
Promising Solution ◽  
The Stability ◽  
Spectroscopy Studies

<p>Passive NO<sub>x</sub> adsorbers (PNA) using Pd/zeolites have emerged as a promising solution for the reduction of cold-start emissions from vehicle exhaust. However, the nature of the active sites and the mechanisms underlying NO<sub>x</sub> adsorption in Pd/zeolites remain a subject of ongoing investigation. In this study, we employ quantum chemical simulations to investigate the structure of Pd species in cation-exchange sites at isolated Al and Al pairs in the 6-ring and 8-ring of the CHA framework, before the introduction of NO<sub>x</sub>. Our calculations show that the speciation of Pd in these exchange sites strongly depends on the precise Al arrangement within the framework, as well as the operating conditions. Ionically dispersed Pd is found to be the most favorable species over a wide range of oxidizing and reducing conditions. Small oligomers of PdO and metallic Pd do not appear to be competitive at either isolated Al or Al pairs. Notably, our calculations show that ion exchange sites other than next-next-nearest neighbor Al pairs in the 6-ring will be preferentially occupied by Pd<sup>+</sup> instead of Pd<sup>2+</sup>. The stability of Pd<sup>+</sup> in the zeolite environment is an interesting contrast with its rareness in molecular Pd compounds. Nonetheless, a detailed analysis of the electronic structure shows that predicted Pd oxidation states are consistent with chemical intuition for all complexes investigated in this study. We also discuss the potential ambiguity in Pd characterization provided by typical experimental techniques such as XANES, EXAFS and UV-VIS, and highlight the need for additional EPR spectroscopy studies to further elucidate the initial Pd speciation in zeolites for PNA applications. </p>

scholarly journals Computational Modeling Predicts the Stability of Both Pd+ and Pd2+ Ion-Exchanged into H-CHA

2020 ◽  
Author(s):  
Jeroen Van der Mynsbrugge ◽  
Martin Head-Gordon ◽  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Nearest Neighbor ◽  
Operating Conditions ◽  
Oxidation States ◽  
Vehicle Exhaust ◽  
Reducing Conditions ◽  
Wide Range ◽  
Promising Solution ◽  
The Stability ◽  
Spectroscopy Studies

<p>Passive NO<sub>x</sub> adsorbers (PNA) using Pd/zeolites have emerged as a promising solution for the reduction of cold-start emissions from vehicle exhaust. However, the nature of the active sites and the mechanisms underlying NO<sub>x</sub> adsorption in Pd/zeolites remain a subject of ongoing investigation. In this study, we employ quantum chemical simulations to investigate the structure of Pd species in cation-exchange sites at isolated Al and Al pairs in the 6-ring and 8-ring of the CHA framework, before the introduction of NO<sub>x</sub>. Our calculations show that the speciation of Pd in these exchange sites strongly depends on the precise Al arrangement within the framework, as well as the operating conditions. Ionically dispersed Pd is found to be the most favorable species over a wide range of oxidizing and reducing conditions. Small oligomers of PdO and metallic Pd do not appear to be competitive at either isolated Al or Al pairs. Notably, our calculations show that ion exchange sites other than next-next-nearest neighbor Al pairs in the 6-ring will be preferentially occupied by Pd<sup>+</sup> instead of Pd<sup>2+</sup>. The stability of Pd<sup>+</sup> in the zeolite environment is an interesting contrast with its rareness in molecular Pd compounds. Nonetheless, a detailed analysis of the electronic structure shows that predicted Pd oxidation states are consistent with chemical intuition for all complexes investigated in this study. We also discuss the potential ambiguity in Pd characterization provided by typical experimental techniques such as XANES, EXAFS and UV-VIS, and highlight the need for additional EPR spectroscopy studies to further elucidate the initial Pd speciation in zeolites for PNA applications. </p>

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