An Inverse Method for Measuring Elastoplastic Properties of Metallic Materials Using Bayesian Model and Residual Imprint from Spherical Indentation

In this paper, an inverse method is proposed for measuring the elastoplastic properties of metallic materials using a spherical indentation experiment. In the new method, the elastoplastic parameters are correlated with sub-space coordinates of indentation imprints using proper orthogonal decomposition (POD), and inverse identification of material properties is solved using a statistical Bayesian framework. The advantage of the method is that model parameters in the numerical optimization process are treated as the stochastic variables, and potential uncertainties can be considered. The posterior results obtained from the measuring method can provide valuable probabilistic information of the estimated elastoplastic properties. The proposed method is verified by the application on 2099-T83 Al-Li alloys. Results indicate that posterior distribution of material parameters exhibits more than one peak region when indentation load is not large enough. In addition, using the weighting imprints under different loads can facilitate the uniqueness in identification of elastoplastic parameters. The influence of the weighting coefficient on posterior identification results is analyzed. The elastoplastic properties identified by indentation and tensile experiment show good agreement. Results indicate that the established measuring method is effective and reliable.

Race/ethnicity in relation to incident primary open-angle glaucoma characterized by autonomously determined visual field loss patterns

Purpose: We used an autonomous algorithm to classify incident visual field (VF) loss patterns in primary open-angle glaucoma (POAG). Subsequently, we compared racial differences in the risk of these regional VF loss patterns. Design/Participants: Participants (n=209,036) from the Nurses Health Study (NHS) (follow-up: 1980-2018); NHS2 (1989-2019); and Health Professionals Follow-up Study (HPFS; 1986-2018), aged ≥40 years and free of glaucoma. Methods: Demographics, medical and lifestyle information was assessed on biennial questionnaires. Incident POAG cases (n=1946) with reproducible Humphrey VF loss were confirmed with medical records. The total deviation information of the earliest reliable VF for each eye with POAG (n=2564) was extracted, and a statistical learning method was used to identified optimal solutions for regional vision loss patterns. Each POAG eye was assigned the VF pattern (archetype) based on the highest weighting coefficient. Multivariable-adjusted hazard ratios (HRs) for POAG of various archetypes and 95% confidence intervals (CIs) were estimated using per-eye Cox proportional hazards models. Covariates included cohort, age, glaucoma family history, socioeconomic status, lifestyle parameters, number of eye exams during follow-up, and medical conditions. False discovery rate (FDR) was used for multiple comparisons. Main outcome measures: POAG based on VF patterns. Results: Mean age was 58 years; 1.3% were Black, 1.2% were Asian, 1.1% were Hispanic-White and 96.4% were non-Hispanic White. We identified 14 archetypes: 1 representing no VF loss, 9 of early loss and 4 of advanced loss patterns. Compared to non-Hispanic Whites, Blacks were at significantly higher risk of POAG with early VF loss archetypes collectively (Blacks: HR=1.96, 95% CI=1.46, 2.63) and at even higher risk for POAG with advanced loss archetypes collectively (Blacks: HR=6.07, 95% CI=3.61, 10.21; p=0.0002 for the two estimates being different); no differences were observed for Asians or Hispanic Whites. For individual VF archetypes, Hispanic-Whites had FDR-significant higher risks of POAG of archetypes showing early paracentral defects and advanced superior loss while Blacks had FDR-significant higher risks of all advanced loss archetypes and 3 early loss patterns, including early paracentral defects. Conclusion: Among health professionals, compared to non-Hispanic-Whites, Blacks and Hispanic-Whites had higher risks of incident POAG with central and advanced VF loss.

Resistive maintenance and equipment criticality indexes

Optimum maintenance of hundreds of thousands of equipment used by each company is one of the main challenges of maintenance, operation, and procurement managers. Continuous production and competition in the business environment and resource constraints require that the vital equipment of each company must be controlled, monitored, and considered. To do this, identifying critical and essential equipment is necessary. In this paper, a formula was defined by field surveys and preferences of 75 petrochemical industry experts and managers to determine the equipment sensitivity index. Experts' opinions extracted ten compelling features in determining the sensitivity of the equipment, and the weighting coefficient of each one was obtained by using the group decision-making method, Analytical Hierarchy Process. The introduction of the resistive maintenance index formula represents the capability to use strengths and opportunities and sustainability and resistance against weaknesses and threats. The original formula has five sub-indicators consisting of equipment effectiveness, labor effectiveness, cost efficiency, degree of endogeneity, extraversion and exogeneity, and the rate of health, safety, and environmental events. From the perspective of 64 specialists, the group decision-making method and paired comparison matrix were used to determine their weighting coefficient.

Years of Life Lost Due to Main Causes of Deaths in Yazd Province, Iran

Aim One approach to measure the demographic impacts of death is to examine the number of lost years of life. The present paper aims to estimate the “Years of Lost Life” (YLL) due to the main causes of death in Yazd province of Iran. Method The present study is an epidemiological examination for which the statistical population included all the death incidents in Yazd province (excluding stillbirth cases) over two time periods of 2011 and 2016 with a 5-year distance. The required data were obtained based on the Comprehensive System of Mortality Registration maintained by the Ministry of Health and Medical Education; while the standard life expectancy data were based on the World Health Organization standards using standard life table, level 26 of the West model (Coale and Demeny) for Japanese men and women. The standard YLL was calculated according to the WHO standard using a 0.03 relaxation rate for the future time and weighting coefficient for various ages and life years through the formula using the Microsoft Excel software. Results The findings of the present study suggest that two main causes of YLL in Yazd province during the year of 2011 were cardiovascular difficulties with the rates of 31.6 per 1000 persons for women and 27.1 per 1000 persons for men, and cancers with the rates of 14.9 per 1000 persons for women and 16.2 per 1000 persons for men. While the above numbers in 2016 were, respectively 22.5 per 1000 persons for women and 25.5 per 1000 persons for men due to cardiovascular difficulties; and 18 per 1000 persons for women and 15.5/1000 for men due to various types of cancers. Conclusions Our findings suggest that cardiovascular diseases and cancers are the main factors leading to Years of Lost Lifetime for the residents of Yazd province in Iran.

An Differential Quadrature Finite Element and the Differential Quadrature Hierarchical Finite Element Methods for the Dynamics Analysis of on Board Shaft

In this paper the dynamic analysis of a shaft rotor whose support is mobile is studied. For the calculation of kinetic energy and stiffness energy, the beam theory of Euler Bernoulli was used, and the matrices of elements and systems are developed using two methods derived from the differential quadrature method (DQM). The first method is the Differential Quadrature Finite Element Method (DQFEM) systematically, as a combination of the Differential Quadrature Method (DQM) and the Standard Finite Element Method (FEM), which has a reduced computational cost for problems in dynamics. The second method is the Differential Quadrature Hierarchical Finite Element Method (DQHFEM) which is used by expressing the matrices of the hierarchical finite element method in a similar form to that of the Differential Quadrature Finite Element Method and introducing an interpolation basis on the element boundary of the hierarchical finite element method. The discretization element used for both methods is a three-dimensional beam element. In the differential quadrature finite element method (DQFEM), the mass, gyroscopic and stiffness matrices are simply calculated using the weighting coefficient matrices given by the differential quadrature (DQ) and Gauss-Lobatto quadrature rules. The sampling points are determined by the Gauss-Lobatto node method. In the Differential Quadrature Hierarchical Finite Element Method (DQHFEM) the same approaches were used, and the cubic Hermite shape functions and the special Legendre polynomial Rodrigues shape polynomial were added. The assembly of the matrices for both methods (DQFEM and DQHFEM) is similar to that of the classical finite element method. The results of the calculation are validated with the h- and hp finite element methods and also with the literature.

The Main Patterns of Disorders of the Visual System in Patients with Retinal Detachment in Pediatric and Adult Practice in Terms of the Level of Antioxidant Protection

The study included patients with a verified diagnosis of “Traction retinal detachment” (RD) in pediatric (50 patients, mean age 13.8 ± 1.1 years, age range from 11 to 18 years) and adults (50 patients, mean age 54, 6 ± 2.2 years, age range 19 to 72 years). The control groups included 25 children (mean age 13.1 ± 1.2 years) and 25 adults (mean age 52.8 ± 1.6 years) patients without pathology of the organ of vision. A comprehensive examination of the functional state of the visual analyzer was performed, including the assessment of clinical (maximum corrected distance visual acuity, BCVA), subjective (Quality of Life, QOL), hemodynamic (pulsation index in the central retinal artery, PI), electrophysiological (threshold of electrical sensitivity of the retina (PESR); threshold of electrical lability of the retina; critical frequency of fusion and flashing (presentation of a red object); photostress test) and biochemical (antioxidant activity in the lacrimal fluid, AOA; superoxide dismutase indicator, PS in the lacrimal fluid) indicators of the visual system. The data obtained indicate some differences in the studied parameters in patients with OS in pediatric and adult practice. In particular, a higher level of BCVA in adults was found (by 18.8 %, p < 0.001). Along with this, it was determined that RD in children is accompanied by more pronounced disorders of hemodynamic and antioxidant parameters, which is associated with a more pronounced degree of proliferative vitreoretinopathy and preservation of antioxidant defense mechanisms. The results of stepwise discriminant analysis of the statistical characteristic F, which determines the weighting coefficient of the relationship in the regression equation of the basic AOA parameter with each indicator in the general array, determined the following most informative indicators (F > 3.0) of the visual system of patients with OS associated with antioxidant protection: in an adult practice — BCVA, QOL, PI, PESR, PS; in pediatric practice — BCVA, PI, PESR, PS. The obtained similar results of statistical analysis for children and adults are actualized by research in pediatric practice aimed at increasing the clinical effectiveness of vitrectomy for RD based on antioxidant protection methods tested in adult practice.

Computationally Efficient Approximations Using Adaptive Weighting Coefficients for Solving Structural Optimization Problems

With rapid development of advanced manufacturing technologies and high demands for innovative lightweight constructions to mitigate the environmental and economic impacts, design optimization has attracted increasing attention in many engineering subjects, such as civil, structural, aerospace, automotive, and energy engineering. For nonconvex nonlinear constrained optimization problems with continuous variables, evaluations of the fitness and constraint functions by means of finite element simulations can be extremely expensive. To address this problem by algorithms with sufficient accuracy as well as less computational cost, an extended multipoint approximation method (EMAM) and an adaptive weighting-coefficient strategy are proposed to efficiently seek the optimum by the integration of metamodels with sequential quadratic programming (SQP). The developed EMAM stems from the principle of the polynomial approximation and assimilates the advantages of Taylor’s expansion for improving the suboptimal continuous solution. Results demonstrate the superiority of the proposed EMAM over other evolutionary algorithms (e.g., particle swarm optimization technique, firefly algorithm, genetic algorithm, metaheuristic methods, and other metamodeling techniques) in terms of the computational efficiency and accuracy by four well-established engineering problems. The developed EMAM reduces the number of simulations during the design phase and provides wealth of information for designers to effectively tailor the parameters for optimal solutions with computational efficiency in the simulation-based engineering optimization problems.

Approaches to Research Methodology of Ethnic Stereotypes (with the Example of the Image of the Estonian in the View of Russian-speaking Students of Estonia)

Ethno-cultural stereotypes are the result of comparing one´s own culture, customs, traditions with that of strangers, identifying and fixing differences between the cultures of ethnic groups. Stereotypical images of different peoples exist even in the minds of those people who had no experience in communication with representatives of these ethnic groups. However, the results of the study of ethnic stereotypes of people who are in direct contact with this ethnic group and see it up close in comparison to people who evaluate it from a distance, often raises more questions than gives clear answers. The solution of these questions raises before the researcher a whole complex of methodological problems. The article will introduce a new methodological approach to reveal ethno-cultural stereotypes in the text culture and in our contemporaries’ common sense perception. To distinguish between people’s individual perception of a particular ethnos and collective stereotypes, the following qualitative and quantitative criteria are suggested: 1) bipolar orthonormal core axes of parameter distribution; 2) the significance of the axis; 3) the degree of consistency of parameters distributed on the axis; 4) the weighting coefficient of testee’s reaction.

Derivation of instantaneous unit hydrographs using linear reservoir models

In this research, a new conceptual model for producing instantaneous unit hydrographs (IUHs) is introduced by a linear combination of the Nash model, which assumes that the discharge from a reservoir is a linear function of its storage, and a model called inter-connected linear reservoir model (ICLRM), which assumes that the discharge from a reservoir is a linear function of the difference of its storage and its adjacent downstream reservoir. By employing these assumptions, a system of first-order linear differential equations with three degrees of freedom (storage coefficient, number of reservoirs, and weighting coefficient) is obtained as the governing equation for the proposed model. This model may be considered as the general form of the two models and is therefore capable of simulating IUHs laying between these two models. To show the capabilities of the model, linear and curvilinear soil conservation service (SCS) hydrographs are simulated using dimensionless hydrographs obtained by this model. Moreover, several real hydrographs were simulated by the proposed model and compared with hydrographs obtained by Nash, ICLRM, and SCS models. The results show that the model yields more accurate results compared to other studied models and may be considered as a new model for simulating IUHs.

Vibration control of improved LQG for wheel drive electric vehicle based on uncertain parameters

To improve the ride comfort of wheel drive electric vehicle, a quarter dynamic model is established for vehicle active and passive suspension. Based on the response root mean square (RMS), the evaluation index of vehicle ride comfort is derived. According to the influence of uncertain parameters on system minimum RMS, the optimal vehicle parameters are determined. To avoid experience value of uncertain weight coefficient affecting the LQG control, analytic hierarchy process (AHP) is adopted to determine the weighting coefficient of vehicle performance evaluation index. And the LQG controller of vehicle active suspension is designed based on optimal control theory. Compared with the analysis results of passive suspension, the effectiveness of active control scheme is verified.