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Abstract\nHIGHLIGHTSCFRP laminates are commonly used in aircraft structures due to their high structural efficiency. The phenomenon-based failures of CFRP laminates have poor predictability for the complex failure process with buckling and matrix fractures. This work carried out seven shear tests of CFRP laminates. It also attempts to reveal its failure characteristic points by directly modeling the measured strain data based on the relative deformation distribution catastrophe. The failure characteristic points are revealed by constructing the stressing state modes/parameters and applying the clustering analysis criterion, whose accuracy can be verified by comparing the shear failure characteristic points of nondestructive/impacted CFRP laminates.Conduct 7 nondestructive/impacted CFRP laminates shear tests.Construct the modes and characteristic parameters characterizing the shear-stressing state of CFRP laminates.Applying clustering analysis criterion to reveal the characteristic loads of CFRP laminates.Verify the accuracy and robustness of the characteristic loads. [ABSTRACT FROM AUTHOR]

In the present paper, the problem of finding the location of the so-called "characteristic point" of flexible footings is revisited. As known, the settlement at the characteristic point is equal to the uniform settlement of the respective rigid footing. The cases of infinitely long strips and circular footings are studied fully analytically. For the case of rectangular footings, analytical results for flexible footings are compared against the respective 3D numerical results for rigid footings; 210 different cases were examined. As shown, the location of the characteristic point may greatly deviate from what it has been proposed in the literature in mid '50s, while it strongly depends on footing shape, as well as on the thickness and the Poisson's ratio of the compressible medium. Apart from the elastic settlement, the characteristic point is also useful in problems involving the knowledge of the vertical stress increase in the compressible medium due to footing loading, such as the consolidation settlement. In this respect, stress influence factor curves are given for rectangular and circular footings. Finally, the applicability and limitations of the "characteristic point" concept are also discussed. [ABSTRACT FROM AUTHOR]

Summary: In the field of ear acupoint therapy in traditional Chinese medicine, many diseases can be treated through ear acupoint acupuncture, buried needle, bleeding, ear acupoint compression, massage, electric stimulation, and other programs. To achieve this goal, the positioning of the earhole feature point region is required. Based on the active appearance model, this article proposes an automatic identification feature point scheme through 168 datasets of data (including data collected based on standard equipment and ordinary mobile phones) collected from Hangzhou Normal University, China. The experimental results show that the average distance error of 91 feature points is less than 6 pixels, which can replace the identification work of TCM ear acupoint doctors. [ABSTRACT FROM AUTHOR]

This study proposes essential design strength and unified strength condition for ETFE membrane materials based on the structural state-of-stress theory and formula of strength. Firstly, the tested strain data of the uniaxial rectangle-shaped specimen are modeled to obtain its state-of-stress characteristic parameter. Then, the characteristic points in the evolution curve of the characteristic parameter are detected by the cluster analysis (CA) criterion. The characteristic points are the embodiment of the natural law from quantitative change to qualitative change of a system, which define the essential strength and the essential design strength of ETFE membrane materials. Further, the essential principal stresses are derived at the characteristic points in the evolution curves of the characteristic parameters obtained by the state-of-stress analysis of the strain data from the tests of air bubbling models and cruciform specimens. Both essential principal stresses and essential strength lead to the unified formula of strength for ETFE membrane materials. Additionally, the unified strength condition is derived for the design of ETFE membrane material structures. Finally, the essential strength, essential design strength, and the unified strength conditions are compared with the existing conditions, providing a rationality to update the existing analysis and design methods for determining the strength of ETFE membrane materials. [ABSTRACT FROM AUTHOR]

This article is a continuation of our research on a one-to-one correspondence between n -dimensional spectral resolutions and n -dimensional observables on lexicographic types of quantum structures which started in Dvurečenskij and Lachman (https://doi.org/10.1016/j.fss.2021.05.005). There we presented the main properties of n -dimensional spectral resolutions and observables, and we studied in depth characteristic points which are crucial for our study. Here we present the main body of our research. We investigate a one-to-one correspondence between n -dimensional observables and n -dimensional spectral resolutions with values in a lexicographic form of quantum structures such as perfect MV-algebras or perfect effect algebras. The multidimensional version of this problem is more complicated than a one-dimensional one because if our algebraic structure is k -perfect for k > 1 , then even for the two-dimensional case of spectral resolutions we have more characteristic points. The results obtained are applied to the existence of an n -dimensional meet joint observable of n one-dimensional observables on a perfect MV-algebra and a sum of n -dimensional observables. [ABSTRACT FROM AUTHOR]

In the paper, we investigate a one-to-one correspondence between n -dimensional observables and n -dimensional spectral resolutions with values in a kind of a lexicographic form of quantum structures like perfect MV-algebras or perfect effect algebras. The multidimensional version of this problem is more complicated than a one-dimensional one because if our algebraic structure is k -perfect for k > 1 , then even for the two-dimensional case we have more characteristic points. The obtained results are also applied to existence of an n -dimensional meet joint observable of n one-dimensional observables on a perfect MV-algebra. The results are divided into two parts. In Part I, we present notions of n -dimensional observables and n -dimensional spectral resolutions with accent on lexicographic type effect algebras and lexicographic MV-algebras. We concentrate on characteristic points of spectral resolutions and the main body is in Part II where one-to-one relations between observables and spectral resolutions are presented. [ABSTRACT FROM AUTHOR]

This study proposes essential design strength and unified strength condition for ETFE membrane materials based on the structural state-of-stress theory and formula of strength. Firstly, the tested strain data of the uniaxial rectangle-shaped specimen are modeled to obtain its state-of-stress characteristic parameter. Then, the characteristic points in the evolution curve of the characteristic parameter are detected by the cluster analysis (CA) criterion. The characteristic points are the embodiment of the natural law from quantitative change to qualitative change of a system, which define the essential strength and the essential design strength of ETFE membrane materials. Further, the essential principal stresses are derived at the characteristic points in the evolution curves of the characteristic parameters obtained by the state-of-stress analysis of the strain data from the tests of air bubbling models and cruciform specimens. Both essential principal stresses and essential strength lead to the unified formula of strength for ETFE membrane materials. Additionally, the unified strength condition is derived for the design of ETFE membrane material structures. Finally, the essential strength, essential design strength, and the unified strength conditions are compared with the existing conditions, providing a rationality to update the existing analysis and design methods for determining the strength of ETFE membrane materials.

The purpose of the article is to reveal the problem (and to determine the possibility of solving the structural choice problem) as one of the areas in modern portfolio theory development. The article also argues that portfolio analysis is a method of structural analysis for various economic units. The research methodology is defined by the portfolio theory, optimization models implemented by the numerical gradient projection method, the empirical static method of analysis and simulation cases when the models are implemented. The research supported by the above- mentioned methodology aimed to reach the goal results in substantiating the structural choice. This choice differs from the classical portfolio choice as it is necessary to find how the investments are allocated for the portfolio units, and the same should be done for the characteristics points, where it is a challenge to apply the efficient set theorem, because different structures for the allocation of the resources, investments give the same or nearly the same combination of the expected return and total portfolio risk. Economic sectors characterized by the profitability and business risk are seen to be the portfolio units in terms of the macroeconomic approach from the portfolio theory developed by Tobin. Total income maximization model and total portfolio risk minimization demonstrate both the structural choice problem, including at the characteristic points, and choice dependence on the expansion of the resource allocated to the portfolio, and on the number of portfolio units. The analysis and model simulations enhance the efficient set theorem with the criteria for structural choice--income and risk correlation on the effective distribution curve, among other factors. A portfolio with two real sectors of the Russian economy illustrates that profitability and risk ratio determines the resource allocation between them under the income maximization model, so one sector grabs a more substantial resource. Thus, being a tool to support the structural choice, portfolio analysis gives structural diagnostics for the resource distribution, investments allocation by portfolio units. [ABSTRACT FROM AUTHOR]

Anthropometric landmarks obtained from three-dimensional (3D) body scans are widely used in medicine, civil engineering, and virtual reality. For all those fields, an acquisition of certain and accurate landmark positions is crucial for obtaining satisfying results. Manual marking is time-consuming and is affected by the subjectivity of the human operator. Therefore, an automatic approach has become increasingly popular. This paper provides a short survey of different attempts for automatic landmark localization, from which one machine learning-based method was further analyzed and extended in the case of input data preparation for a convolutional neural network (CNN). A novel method of data processing is presented which utilize a mid-surface projection followed by further unwrapping. The article emphasizes its significance and the way it affects the outcome of a deep neural network. The workflow and the detailed description of algorithms used are included in this paper. To validate the method, it was compared with the orthogonal projection used for the state-of-the-art approach. Datasets consisting of 200 specimens, acquired using both methods, were used for convolutional neural networks training and 20 for validation. In this paper, we used YOLO v.3 architecture for detection and ResNet-152 for classification. For each approach, localizations of 22 normalized body landmarks for 10 male and 10 female subjects of different ages and various postures were obtained. To compare the accuracy of approaches, errors and their distribution were measured for each characteristic point. Experiments confirmed that the mid-surface projections resulted, on average, in a 14% accuracy improvement and up to 15% enhancement of resistance on errors related to scan imperfections. [ABSTRACT FROM AUTHOR]

In this study, the calculating principle of the meshing limit line of the conical surface enveloping conical worm pair is put forward systematically. The tooth face equations, the meshing function and the meshing limit function of a conical worm pair are all acquired. Investigating the meshing limit line is come down to solving an equivalent unary nonlinear equation, which is determined from its original equations with four variables by means of the elimination technique. Based on this, the meshing limit line characteristics are deeply researched after resolving preceding equation correctly. The numerical results declare that there may be two meshing limit lines on each helicoid of one tooth of an enveloping conical worm although not all of them have physical significance. All the significative meshing limit lines usually do not get into the worm helicoid and have no influence on its normal work. Therefore, the active length of the worm depends on the tooth face boundary of the conical worm wheel theoretically. Besides, when the center distance of the worm pair is less, the transmission ratio is larger and the number of thread of the worm is more, the meshing limit line may be closer to the little end of the conical worm e helicoid. [ABSTRACT FROM AUTHOR]

We construct a finite-time blow-up solution for a class of strongly perturbed semilinear wave equation with an isolated characteristic point in one space dimension. Given any integer k ≥ 2 and ζ 0 ∈ R , we construct a blow-up solution with a characteristic point a , such that the asymptotic behavior of the solution near (a , T (a)) shows a decoupled sum of k solitons with alternate signs, whose centers (in the hyperbolic geometry) have ζ 0 as a center of mass, for all times. Although the result is similar to the unperturbed case in its statement, our method is new. Indeed, our perturbed equation is not invariant under the Lorentz transform, and this requires new ideas. In fact, the main difficulty in this paper is to prescribe the center of mass ζ 0 ∈ R. We would like to mention that our method is valid also in the unperturbed case, and simplifies the original proof by Côte and Zaag [9] , as far as the center of mass prescription is concerned. [ABSTRACT FROM AUTHOR]

The determination of characteristic points of bioimpedance curves is crucial to the analysis of bioimpedance signals. Traditional methods need to calculate the derivative of the bioimpedance curve and rely on the help of other simultaneously recorded signals. However, these methods are sensitive to noise while some auxiliary signal may be unrecorded. A novel approach is proposed in this study to automatically determine the positions of characteristic points. The overall development process is realized as a two-phase construct. The first stage of the process involves a fitting of the impedance change curves using nonlinear regression models. Then, a prediction model is trained to predict the positions of characteristic points through a linear combination of the parameters of the nonlinear regression model. Experimental studies constructed on a collection of real-world bioimpedance signals help quantify the performance of the algorithm and gain a deep insight into the superiority of the proposed methodology. It is shown that the proposed method offers a substantial improvement in the prediction accuracy in comparison with the baseline method. Moreover, the proposed characteristic point determination method is robust to noise since its performance is not affected in the presence of noise. • The aim is to automatically determine the positions of characteristic points of bioimpedance signals. • Nonlinear regression models are used to capture the nonlinear and non-stationary characteristics of bioimpedance signals. • The proposed method works well when bioimpedance signals are usually corrupted by noises. • Traditional existing methods are sensitive to noise and rely on other auxiliary signals to work. [ABSTRACT FROM AUTHOR]

Anthropometric landmarks obtained from three-dimensional (3D) body scans are widely used in medicine, civil engineering, and virtual reality. For all those fields, an acquisition of certain and accurate landmark positions is crucial for obtaining satisfying results. Manual marking is time-consuming and is affected by the subjectivity of the human operator. Therefore, an automatic approach has become increasingly popular. This paper provides a short survey of different attempts for automatic landmark localization, from which one machine learning-based method was further analyzed and extended in the case of input data preparation for a convolutional neural network (CNN). A novel method of data processing is presented which utilize a mid-surface projection followed by further unwrapping. The article emphasizes its significance and the way it affects the outcome of a deep neural network. The workflow and the detailed description of algorithms used are included in this paper. To validate the method, it was compared with the orthogonal projection used for the state-of-the-art approach. Datasets consisting of 200 specimens, acquired using both methods, were used for convolutional neural networks training and 20 for validation. In this paper, we used YOLO v.3 architecture for detection and ResNet-152 for classification. For each approach, localizations of 22 normalized body landmarks for 10 male and 10 female subjects of different ages and various postures were obtained. To compare the accuracy of approaches, errors and their distribution were measured for each characteristic point. Experiments confirmed that the mid-surface projections resulted, on average, in a 14% accuracy improvement and up to 15% enhancement of resistance on errors related to scan imperfections.

In this paper the strain energy density (SED) model is used to analyze the seismic behavior of suspen-domes and a new criterion is established for judging the seismic failure based on a characteristic point in the SED model. Firstly, a nonlinear time-history response analysis was carried out using the finite-element package ANSYS for typical suspen-domes subjected to different ground motions. The seismic responses including nodal displacements, ratios of yielding members, strain energy density and structural maximum deformation energy were extracted corresponding to the increasing peak ground acceleration (A). Secondly, the SED sum (Id) was calculated which revealed that the Id-A curve exhibited a relatively large change (called a characteristic point) at a certain value of A with a very small load increment after the structures entered the elastic-plastic state. Thirdly, a SED criterion is proposed to judge the seismic failure load based on the characteristic point. Subsequently, the case study verifies the characteristic point and the proposed SED criterion. Finally, this paper describes the unity and application of the SED criterion. The SED method may open a new way for structural appraisal and the SED criterion might give a unified criterion for predicting the failure loads of various structures subjected to dynamic loads. [ABSTRACT FROM AUTHOR]