Influence Function Method Research Articles

Analytic Approaches to Measuring the Black-White Wealth Gap

Does the measurement of the racial wealth gap shift depending on the model, method, and dataset used? We contrast the traditional mean Oaxaca-Blinder decomposition with the distributional Recentered Influence Function (RIF) methods. The untransformed, logarithm-transformed, and inverse hyperbolic sine-transformed versions in both the Survey of Consumer Finances and Panel Study of Income Dynamics datasets exhibit similarities. The Oaxaca-Blinder (mean) decomposition highlights that receiving an inheritance explains a larger portion of the racial wealth gap than educational attainment. Conversely, the RIF method at the median suggests that educational attainment accounts for more of the wealth gap than inheritance receipt.

Calculation and Discussion for Crack Driving Force of Dissimilar Metal Welded Joint of Nuclear Power Equipment Nozzle and Safe End

This study investigates the effects of the material mechanical properties heterogeneity and strength mismatch variation on crack driving forces for cracks in a dissimilar metal welded joint (DMW) of a reactor pressure vessel inlet nozzle to the safe end. Linear elastic and elastic-plastic analyses are carried out to calculate the stress intensity factor (SIF) and J-integral for cracks in the DMW. The effects of crack locations, crack depths, and strength mismatch factors on the SIF and J-integral are studied. The SIF results obtained by finite element analysis are compared with those obtained by the influence function method adopted in the nuclear power code. Results show that the effect of crack location on the SIF can be ignored. The SIFs calculated by the influence function method for cracks in the DMW are basically reasonable, although its conservatism is slightly insufficient. Moreover, with moving the crack location from the nozzle through buttering and weld metal to the safe end, the J-integral increases. The effect of the crack location and strength mismatch factors on the J-integral is essentially caused by variation of the plastic zone and the material properties of the crack front. The crack sizes affect the level of influence of the crack location and the strength mismatch factors on the J-integral. The J-integral increases with decrease of the strength mismatch factor.

The role of institutions on public debt: A quantile regression approach

The unprecedented rise in debt levels across countries has given rise to the role of institutions on public debt. This study examines the impact of institutions on government debt in a sample of 54 EU and non-EU countries, covering the 2010 to 2022 period, employing the Logistic Quantile Regression (LQR) and Recentered Influence Function (RIF) method, Our results indicate that the effect of institutions varies across the distribution of government debt. The results show that government effectiveness, regulatory quality, voice, and accountability have similar effects in the EU and non-EU countries. However, political stability and the control of corruption have a significant and debt reducing effect only in EU countries. Robustness checks confirm our findings.

Tool mark prediction on the surface of large-aperture mirrors via magnetorheological finishing.

The magnetorheological finishing (MRF) of surfaces often results in tool mark errors. A prediction model can effectively guide subsequent processing, necessitating thorough research. To address this issue, this paper introduces an enhanced continuous tool influence function method. This method involves sub dwell time convolution with varying tool influence functions, enabling tool mark prediction. Numerical simulations demonstrate the proposed method's effectiveness, while the data size is estimated to confirm its economic properties. Subsequently, a MRF experiment was conducted, affirming the practicability through power spectral density evaluation. A fast algorithm is given to guide tool mark predictions on large-aperture mirrors fabrication engineering subjected to sub-aperture polishing.

A happy home? Socio-economic inequalities in depressive symptoms and the role of housing quality in nine European countries

BackgroundThis study examines the prevalence of and socio-economic inequalities in depressive symptoms in nine high-income European countries, focusing in particular on the role of housing quality.MethodsUsing the European Social Survey, a concentration index of depressive symptoms in each country is estimated. The role of housing quality is assessed by examining the risk factors associated with the concentration index, using the Recentred Influence Function method. To contextualise the housing quality results, other predictors of inequalities in depressive symptoms inequalities are also quantified and discussed.ResultsOur results indicate that inequalities in depressive symptoms are concentrated among poorer respondents both in each country and in total. Austria and Belgium have the lowest inequalities and France has the highest. No geographic pattern is evident. Housing problems are associated with higher inequalities in six of the nine countries in the sample. While no association is evident for indicators of socio-economic status such as years of education and income, financial strain is significant.ConclusionsThis study is the first to estimate the degree of socio-economic inequality in depressive symptoms across European countries. The association between poor housing and poorer inequalities suggests that housing has a role to play lowering depressive symptoms inequalities.

Numerical analysis of contact pressure between rolls of Sendzimir mill based on double influence function method and conjugate gradient techniques

This paper established a model for calculating the contact pressure between the rolls of the Sendzimir 20-high mill based on the influence function method with considering the dispersion distribution characteristics of backup rolls. Stone's and Hirschcock's formula are used to calculate the rolling force between the work rolls and the rolling stock. The force balance equations and the moment balance equations of the roll system are established to determine the relationship between the contact pressure of rolls and the rolling force. The deformation-compatibility equation is established by combining the flattening deformation, deflection deformation, and rigid displacement of the rolls and roll crown. The influence function method is used to solve the flattening deformation and deflection deformation between the rolls. The conjugate gradient method is used to solve the contact pressure between the rolls by combining the force balance equation group, the moment balance equation group, and the deformation compatibility equation group of the roll system. The contact pressure between rolls obtained by the model established is compared to that by the finite element method. The results show that the calculation accuracy of the model established in this paper is consistent with that of the finite element method. Significantly, the contact pressure between the backup roll and the second intermediate roll can be accurately calculated by considering the dispersion distribution characteristics of the backup roll, and the computation time can be greatly reduced.

Influence coefficient based fracture parameter modification factor in a cracked T-butt welded joint

An influence coefficient based modification factor (μk) method and its regression formulae are proposed. The μk can be used to calculate the stress intensity factor (SIF) in a cracked T-butt welded joint under arbitrary stress distribution. By multiplying μk with the SIFs of a flat plate obtained by numerical influence function method (NIFM), mixed-mode SIFs (MM-SIFs) for a T-butt joint can be readily evaluated. T-butt joints with semi-circular surface cracks are employed in the numerical examples. The MM-SIFs calculated by the μk method were verified against those computed under direct membrane loading, and under welding residual stress conditions. An adequate agreement was achieved between the solutions given by the proposed μk method and the reference numerical analyses. Therefore, the MM-SIFs of surface-cracked T-butt joints under arbitrary stress distributions can be evaluated using the developed μk formulae.

Research on the on-line fracture assessment of cracked primary loop pipes in NPPs

The cracked pipes usually need to be replaced or conservatively evaluated in the Nuclear Power Plants (NPPs). There is still a lack of effective methods for a real-time crack propagation and safety evaluation based on massive monitoring transient data. In order to ensure the safe and economic operation of the NPPs, the authors have developed an on-line fracture assessment technology in this paper. The calculation method of total stress suitable for on-line monitoring data, optimizing the calculation method of transient thermal stress and stress intensity factor (SIF) based on the influence function method are discussed. Then, the on-line software for the primary loop hot-leg pipe which is based on the research results is developed. In this paper, an on-line safety assessment method based on the monitoring data which can meet the requirements of the in-service inspection code (RSE-M Code) is given. The influence function is proposed to be established at a fixed time interval which will make the computational complexity reduced significantly. By the parallel calculation method and the characteristics of the algorithm, the origin algorithm along the time axis is optimized to an algorithm that can be calculated to obtain the target parameters at each time point within the specified attenuation time range of the influence function. Then the calculation efficiency is significantly improved. By compiling the data and calculation methods in the code, the calculation method of SIF suitable for on-line monitoring is obtained, and the reliability is also verified by the analyzed case. Based on the technical results obtained from the research and the requirements in the RSE-M Code, the re-development is carried out in the general commercial software platform. The software is developed, and it is demonstrated that it has sufficient analysis accuracy.

Towards a computational engineering tool for structural sensitivity analysis based on the method of influence functions

This contribution presents a computational engineering tool for the purposeful and systematic investigation how sensitive responses of a structural analysis model react due to variations of model parameters. The methodical basis of the approach is the relationship between adjoint sensitivity analysis and the classical and well-known technique of influence functions. The strong connection between the two approaches allows the extension of the traditional method of influence functions as a tool for the evaluation of sensitivities for general responses, parameters and structures. The paper provides a detailed discussion of that methodical relationship and shows how the influence function of important responses in structural engineering can be identified in the adjoint sensitivity equation. Following the ability of the traditional method of influence functions to provide structural comprehension as visual means, also the results of sensitivity analysis are graphically processed as maps. Finally, the application of the presented method and the sensitivity maps is demonstrated by means of expressive engineering structures. The examples provide insights how sensitivity analysis can support the structural design process by fast and purposeful identification and further assessment of the importance of model parameters.

Advanced non-dimensional dynamic influence function method considering the singularity of the system matrix for accurate eigenvalue analysis of membranes

An advanced non-dimensional dynamic influence function method (NDIF method) for highly accurate free vibration analysis of membranes with arbitrary shapes is proposed in this paper. The existing NDIF method has the weakness of not offering eigenvalues and eigenmodes in the low frequency range when the number of boundary nodes of an analyzed membrane is increased to obtain more accurate result. This paper reveals that the system matrix of the membrane becomes singular in the lower frequency range when the number of the nodes increases excessively. Based on this fact, it provides an efficient way to successfully overcome the weaknesses of the existing NDIF method and still maintain its accuracy. Finally, verification examples show the validity and accuracy of the advanced NDIF method proposed.

Influence function methods to assess the effectiveness of influenza vaccine with survey data.

To examine a robust relative risk (RR) estimation for survey data analysis with ideal inferential properties under various model assumptions. We employed secondary data from the Household Component of the 2000-2016 US Medical Expenditure Panel Survey (MEPS). We investigate a broad range of data-balancing techniques by implementing influence function (IF) methods, which allows us to easily estimate the variability for the RR estimates in the complex survey setting. We conduct a simulation study of seasonal influenza vaccine effectiveness to evaluate these approaches and discuss techniques that show robust inferential performance across model assumptions. Demographic information, vaccine status, and self-administered questionnaire surveys were obtained from the longitudinal data files. We linked this information with medical condition files and medical event to extract the disease type and associated expenditures for each medical visit. We excluded individuals who were 18 years or younger at the beginning of each panel. Under various model assumptions, the IF methods show robust inferential performance when the data-balancing procedures are incorporated. Once IF methods and data-balancing techniques are implemented, contingency table-based RR estimation yields a comparable result to the generalized linear model approach. We demonstrate the applicability of the proposed methods for complex survey data using 2000-2016 MEPS data. When employing these methods, we find a significant, negative association between vaccine effectiveness (VE) estimates and influenza-incurred expenditures. We describe and demonstrate a robust method for RR estimation and relevant inferences for influenza vaccine effectiveness using MEPS data. The proposed method is flexible and can be extended to weighted data for survey data analysis. Hence, these methods have great potential for health services research, especially when data are nonexperimental and imbalanced.

Numerical study on the effect of residual stresses on stress intensity factor and fatigue life for a surface-cracked T-butt welded joint using numerical influence function method

Numerical study on the effect of residual stresses on stress intensity factor and fatigue life for a surface-cracked T-butt welded joint using numerical influence function method

Influence Function and Bootstrap Methods of Estimating the Standard Errors of the Estimators of Mixture Exponential Distribution Parameter

This work estimated the standard error of the maximum likelihood estimator (MLE) and the robust estimators of the exponential mixture parameter (θ) using the influence function and the bootstrap approaches. Mixture exponential random samples of sizes 10, 15, 20, 25, 50, and 100 were generated using 3 mixture exponential models at 2%, 5% and 10% contamination levels. The selected estimators namely: mean, median, alpha-trimmed mean, Huber M-estimate and their standard errors (Tn ) were estimated using the two approaches at the indicated sample sizes and contamination levels. The results were compared using the coefficient of variation, confidence interval and the asymptotic relative efficiency of Tn in order to find out which approach yields the more reliable, precise and efficient estimate of Tn. The results of the analysis show that the two approaches do not equally perform at all conditions. From the results, the bootstrap method was found to be more reliable and efficient method of estimating the standard error of the arithmetic mean at all sample sizes and contamination levels. In estimating the standard error of the median, the influence function method was found to be more effective especially when the sample size is small and yet contamination is high. The influence function based approach yielded more reliable, precise and efficient estimates of the standard errors of the alpha-trimmed mean and the Huber M-estimate for all sample sizes and levels of contamination although the reliability of the bootstrap method improved better as sample size increased to 50 and above. All simulations and analysis were carried out in R programming language.

Enhanced Subsurface Subsidence Prediction Model Incorporating Key Strata Theory

Subsurface strata movements and deformations associated with longwall mining operations in underground coal mines could cause various disturbances to subsurface mine structures, ground water bodies, and coalbed methane reservoirs. In order to assess those disturbances correctly and to design effective and efficient mitigation measures, it is necessary to develop an accurate prediction model for subsurface strata movements and deformations. Decades of research have demonstrated that variations of stratification and lithology in the overburden have significant influence on the subsurface strata movements and deformations during ground subsidence process. The key strata theory states that the thick and hard key strata serve as the backbone of the overburden and control the movements of the thin and soft weak strata located above them. From an engineering standpoint, the overburden strata are subdivided into several individual groups by the key strata with each group consisting of a key layer at the bottom and weak layers overlying it. A new subsurface subsidence prediction model considering the key strata effects on subsurface strata movements and deformations has been proposed. In this method, elastic modulus, specific weight, tensile strength, and uniaxial compressive strength (UCS) of each layer are used to identify the key layers and to determine the needed subsurface subsidence parameters. The influence function method, proven to be accurate and versatile for surface subsidence prediction, was employed to predict the subsidence on each of the overburden layers from mining horizon progressively upward to ground surface with the assumption that the predicted subsidence on a given layer serves as the subsidence source for the layer immediately above. The enhanced subsurface subsidence prediction model has been demonstrated with an actual case to show its applicability and improvement.

An improved methodology for applying the influence function for subsidence hazard prediction

ABSTRACT The extraction of ore and minerals by underground mining often presents important risk for surface infrastructures. Several methods that have been developed to predict ground subsidence, and the influence function method (IFM) is one of the most efficient for predicting this phenomenon in the context of mining engineering. However, applying this method to a specific mining site requires adjustments that are difficult to achieve. In this paper, a methodology is proposed for adjusting the IFMs to each mining site. It is shown that the maximum subsidence depends on both the Width(W)/Height(H) and Length(L)/W ratios of mine panel. Moreover, the effect of the length variation becomes negligible for L/W ratio values greater than 4, but it is significant for values around 1. The influence angle of each mine panel has a significant effect on the subsidence, and a variation of 5° may lead to significant variations in the prediction. A coefficient of dimensions reduction (CDR) used for adjusting the IFM results in each mine panels is used to adjust the value of subsidence above the border of the mine panels. The appropriate influence angle and CDR parameters should be calculated for each mining region.

“Future Earth”: Nigmatulin Hypothesis and Dynamic Model of Radiation Field of Ocean-Atmosphere System

The United Nations has proclaimed a Decade of Ocean Science for Sustainable Development (2021-2030) to support efforts to reverse the cycle of decline in ocean health and gather ocean stakeholders worldwide behind a common framework that will ensure ocean science can fully support countries in creating improved conditions for sustainable development of the Ocean. The marine realm is the largest component of the Earth’s system that stabilizes climate and support life on Earth and human well-being. Scientific understanding of the ocean’s responses to pressures and management action is fundamental for sustainable development. Planet Earth is a natural example of a dynamic system with nonlinear processes that is in continuous change. The Earth’s radiation field is a single physical field (electromagnetic radiation) and the unifying factor of the Earth dynamical system. The Earth’s climate system is a natural environment that includes the atmosphere, the hydrosphere (oceans, seas, lakes, rivers), the cryosphere (land surface, snow, sea and mountain ice, etc.), and the biosphere that unites all living things. According to the hypothesis of R.I. Nigmatulin “Ocean is a dictator of climate”. H2O and CO2 are competing climate influences. In this article, we propose original author’s mathematical models for radiation blocks with hyperspectral data on absorption by atmospheric components. The new models are based on the development of the theory of the optical transfer operator and the method of influence functions in the theory of radiation transfer and Boltzmann equations, as well as the iterative method of characteristics with iteration convergence accelerations.

Advanced NDIF Method for Eigenvalue Analysis of Arbitrarily Shaped Acoustic Cavities With the Partially Pressure-Release Boundary

Abstract In this paper, an advanced non-dimensional dynamic influence function method (NDIF method) for eigenvalue analysis of arbitrarily shaped two-dimensional acoustic cavities with the mixed boundary consisting of the pressure-release and rigid-wall boundaries is proposed. The existing NDIF method has the weakness of having to calculate the singularity of the final system matrix of an analyzed acoustic cavity in the frequency band of interest to obtain the eigenvalues of the cavity because the final system matrix is dependent on the frequency. The newly proposed NDIF method in this paper provides an efficient way to extract accurate eigenvalues and eigenmodes by successfully overcoming the above weaknesses. Finally, the validity and accuracy of the proposed method are shown through verification examples.

Dynamic Permeability Change Model of Strata over Mining Coal Seam

In an underground mining operation, the overlying strata moves, deforms and even cracks as the working face advances due to strata breakage and failure, forming a “vertical-three-zone”. The permeability of strata under mining changes differently. Models for calculating the strata subsidence for such zones and analyzing strata collapsing development for the caving zone are proposed based on the influence function method and mechanical analyses. In addition, on the basis of such models, a new comprehensive model to describe the permeability change of strata is developed.

Social well-being inequality in Africa

ABSTRACT In this paper, we construct a composite social well-being index to investigate disparities between 30 African countries. We do this because previous inequality studies relied on income measures; however, when it comes to Africa, specifically, income is not an adequate measure to capture well-being. Furthermore, we apply the recentered influence function (RIF) method to regress the variance of social well-being on likely influencing factors. Lastly, we use the Blinder–Oaxaca decomposition technique to investigate the gap between countries with higher, and those with lower levels of social well-being. The results indicate that there are high levels of inequality; however, the inequality in social well-being is less stark than in income. Factors that are significantly related to inequality are employment, gender equality, exports, CO2 emissions, population density, public protests, capital investment, and internet access. The gap that exists between higher and lower social well-being countries is mainly due to the endowment effect.

An innovative strata movement model for predicting overlying strata deformations

The overlying strata in mining could move, deform and break with the advancement of the underground mining operations and form the “three-vertical-zones” over the mined-out areas. In this paper, the influence function method based to predict the surface subsidence is innovatively introduced to establish the movement model of subsurface strata over underground mine gob. In order to validate the developed model’s reliability, the model is applied in a Chinese underground mine to calculate the subsurface strata movements. Then a physical simulation modelling is also conducted to study the behavior of rock strata affected by mining. By using cross-validation, the theoretical results are compared with the physical simulations, which indicates that those two results are highly agreed with each other. The reliability of developed model can be a good tool to study the progress of subsurface stratum bedding and caving in a coal mine.