The load separation and η pl

Load separation is the theoretical basis for the single specimen J form and the incremental calculation of J-R and J _M -R curves. It is based on the assumption that the load can be represented as a multiplication of two separate functions; a crack geometry function and a material deformation function. Until recently, the main experimental basis for such an assumption was the approximate agreement between the experimental results of the single specimen J form and the energy rate interpretation of J in blunt notched bending geometries. The load separation assumption has been also implied in the growing crack records in order to develop the R-curve analysis. Both the crack geometry and material deformation functions were assumed to maintain their forms as the crack grows. Recently, an experimental study investigated the load separation in the test records of stationary crack specimens of different geometry, material, and constraint. The study showed that the load can be represented by a separable form for the entire plastic region except for a limited region at the early region of plastic behavior. Also, it was found that the load separation is not limited to a certain geometry, material, or constraint but it is a dominant property in the ductile fracture behavior of stationary crack specimens. The study also showed that the crack geometry function is a power law function. Hence _pl is a constant equal to the power law exponent of the geometry function.The objective of this study is to investigate the extension of load separation to growing crack records. Sets of test records from three different materials are used in this study. For each material three or four precracked specimen test records and one blunt notched record are analyzed for the compact specimen geometry. The study will discuss the main condition to have a separable behavior in a growing crack test record. It will also construct the geometry and deformation functions for the materials studied, these functions are compared with those obtained from stationary crack records.     

Normalized load‐deflection curves of lateral piles in homogeneous elasto‐plastic soils

Abstract

In this paper, the procedure of normalizing load‐deflection curves of lateral piles in a homogeneous elasto‐plastic soil is presented. An analytical method using subgrade reactions reveals that the normalized relation of load‐deflection exists for force, moment or combined load. The normalized curves for force and moment load fit very well with the predictions using the equations. For the combined load, the normalized curves are distributed between the force and moment load curves, so it is easy to use interpolation from a family of curves. These normalized curves provide a very convenient way for calculating the pile load or deflection in the design stage.     

Fast and robust estimation of the multivariate errors in variables model

In the multivariate errors in variables models, one wishes to retrieve a linear relationship of the form y=β ^t x+α, where both x and y can be multivariate. The variables y and x are not directly measurable, but observed with measurement error. The classical approach to estimate the multivariate errors in variables model is based on an eigenvector analysis of the joint covariance matrix of the observations. In this paper, a projection-pursuit approach is proposed to estimate the unknown parameters. The focus is on projection indices based on half-samples. These lead to robust estimators which can be computed using fast algorithms. Fisher consistency of the procedure is shown, without the need to make distributional assumptions on the x-variables. A simulation study gives insight into the robustness and the efficiency of the procedure.     

Can tissue weighting factors be established for the embryo and fetus?

For the calculation of effective dose (E), tissue weighting factors (wT) are needed to represent the varying radiosensitivity of the tissues in the human body with respect to the induction of stochastic effects. The wT-values have been determined by the International Commission on Radiological Protection according to the stochastic detriment of human populations during their postnatal life. This study discusses whether these wT-values can also be used for the embryo/fetus. For this purpose, the epidemiological data and some results from animal experiments on carcinogenesis after prenatal radiation exposures have been reviewed. Most human data have been obtained from studies of childhood cancers (<19 y of age) after exposures during prenatal development. These tumours differ from those observed later in life after radiation exposures of children and adults. From animal data and more recent results from the atomic bomb survivors, it appears that not only childhood cancers but also cancers occurring during adulthood would have to be considered for the determination of possible wT-values after prenatal irradiation. From the present data it is concluded that sufficient data for defining wT-values following exposure of the embryo/fetus are not available at present.     

Effects of pressure sensitivity on the η factor and the J integral estimation for compact tension specimens

In this paper, the effects of pressure-sensitive yielding on the factor and the J integral estimation for compact tension specimens are investigated. The analytical expressions for and J for pressure-insensitive von Mises materials are generalized to pressure-sensitive Drucker-Prager materials using a lower bound approach. The factor as a function of the pressure sensitivity and the normalized crack depth for compact tension specimens is derived under plane stress and plane strain conditions. The numerical results indicate that the factor decreases as the pressure sensitivity increases. The effects are more pronounced under plane strain conditions than under plane stress conditions. However, the effects of the pressure sensitivity on are found to be mild in general. For rigid perfectly-plastic materials, the J estimation for pressure-sensitive materials is also reduced to a simple expression of the tensile yield stress times the crack tip opening displacement as for the von Mises materials.     

Human factors and ergonomics in manufacturing in the industry 4.0 context – A scoping review

Industry 4.0 revolution has brought rapid technological growth and development in manufacturing industries. Technological development enables efficient manufacturing processes and brings changes in human work, which may cause new threats to employee well-being and challenge their existing skills and knowledge. Human factors and ergonomics (HF/E) is a scientific discipline to optimize simultaneously overall system performance and human well-being in different work contexts. The aim of this scoping review is to describe the state-of-the-art of the HF/E research related to the industry 4.0 context in manufacturing. A systematic search found 336 research articles, of which 37 were analysed utilizing a human-centric work system framework presented in the HF/E literature. Challenges related to technological development were analysed in micro- and macroergonomics work system frameworks. Based on the review we frame characteristics of an organisation level maturity model to optimize overall sociotechnical work system performance in the context of rapid technological development in manufacturing industries.     

A new method for measuring the shape and size of the plastic zones around slit ends — the direct showing method

The direct showing method is a new method for measuring the plastic zones by using photoelastic coating technique. An experimental study for the plastic zones of four kinds of metal thin plate tensile specimens containing slits has been made by the method. Some typical experimental results and primary knowledge have been given in this paper. Non-symmetrical isochromatic fringe patterns and plastic zones were observed in annealed B3 thin steel plate specimens. This non-symmetrical phenomenon is well worth further research.     

Validation of an EcosimPro® model for the assessment of two heat load smoothing strategies in the HELIOS experiment

HELIOS experiment, installed at CEA Grenoble, is a scaled down helium loop for investigating high pulsed loads on superconducting magnet cooling circuits of Tokamak. Heat loads have to be smoothed down in order to ensure refrigerator stability. A real time simulation is of interest for reproducing the thermohydraulic phenomenon observed experimentally. The modelling work has been carried out with EcosimPro simulation software combined with a specific cryogenic library. Existing components were modified with additional features, particularly for taking into account 1D fluid transport. The model comprises a closed loop with forced flow supercritical helium at 4.4 K and 5 bar connected through heat exchangers to a saturated helium bath at 1.1 bar. The new heat load mitigation strategies presented in this paper are based on two kinds of regulations in order to smooth the helium mass flow retuning to the refrigerator. First strategy uses the bath as a thermal buffer by acting on bath outlet control valve. Second one uses the variation of the circulator speed to induce a delay in the arrival of the heat loads into the helium bath. The model with the two controls is validated against comparisons with experimental data.     

Study of the load-separation principle and a procedure to estimate ηp-factor for structures with different geometries

The theoretical background of load separation principle has been reviewed. Based on dimensional analysis, experimental results and finite element analysis the conditions for the validity of this principle have been studied and a method has been suggested to estimate the load separation function, and hence to estimate the _p-factor and to determine the J-R resistance curve easily from records of a single specimen or structure.     

Study of the monopolar RWG and monopolar n×RWG basis functions for electromagnetic scattering analysis

In this paper, we study the accuracy and the efficiency of the monopolar divergence-conforming Rao–Wilton–Glisson (RWG) and the monopolar curl-conforming n×RWG basis functions for the magnetic field integral equation (MFIE). Similar to cases using RWG and n×RWG basis functions for the MFIE, there are two impedance matrix elements calculation schemes if the monopolar RWG and monopolar n×RWG basis functions are used to the MFIE, respectively. The monopolar basis functions and the implementation schemes used for the MFIE are discussed. The scattering cross section data as well as the CPU time needed to fill the corresponding impedance matrix obtained from numerical solutions of these implementation schemes using monopolar basis functions are investigated. For the monopolar basis functions and the implementation schemes considered, the first scheme of the MFIE using the monopolar curl-conforming n×RWG basis functions gives most accurate results and it is the best choice for the use of the monopolar basis functions to the MFIE.     

Quality is in the eye of the beholder? An evaluation of impact factors and perception of journal prestige in the UK

A number of proxy measures have been used as indicators of journal quality. The most recent and commonly employed are journal impact factors. These measures are somewhat controversial, although they are frequently referred to in establishing the impact of published journal articles. Within psychology, little is known about the relationship between the ‘objective’ impact factors of journals and the ‘subjective’ ratings of prestige and perceived publishing difficulty amongst academics. In order to address this, a cross-sectional web-based survey was conducted in the UK to investigate research activity and academics’ views of journals within three fields of psychology; cognitive, health and social. Impact factors for each journal were correlated with individual academic’s perceptions of prestige and publishing difficulty for each journal. A number of variables pertaining to the individual academic and their place of work were assessed as predictors of these correlation values, including age, gender, institution type, and a measure of departmental research activity. The implications of these findings are discussed in relation to perceptions of journal prestige and publishing difficulty, higher education in general and the assessment of research activity within academic institutions.     

Heat capacity and thermodynamic functions of zinc metaarsenate in the range 298.15–673 K

The isobaric heat capacity of Zn(AsO₃)₂ is measured by a calorimetric method in the range 298.15–673 K. From the data obtained the temperature dependences of the functions C_kp/0(T), S⁰(T), H⁰(T)–H⁰(298.15), and ^** are calculated.Chemical Metallurgy Institute, Academy of Sciences of Kazakhstan, Karaganda. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 4, pp. 647–650, July–August, 1995.     

Low-loss gears precision planetary gearboxes: reduction of the load dependent power losses and efficiency estimation through a hybrid analytical-numerical optimization tool

In the field of robotics, extremely accurate gearboxes are mandatory in order to ensure the adequate precision required by the automatic processes. For these applications, planetary gearboxes represent one of the most attractive solutions because they ensure high reduction ratios in a compact solution.However, their compactness and high power density, imply some thermal limitations.In order to overcome this problem, new gear designs have been studied by a hybrid analytical-numerical approach in order to reduce the power dissipation and, consequently, the operating temperatures.The efficiency increase is obtained mainly by a reduction of the module of the gears. This, together with other modifications of the tooth form (pressure angle, profile shift, etc.), allows to reduce the relative sliding between the tooth flanks that causes the power loss maintaining at the same time an adequate load carrying capacity.Low-loss gears have already been studied by other authors on bigger gears. Furthermore, by means of dedicated CFD simulations performed with an especially developed tool based on the open-source code OpenFOAM®, it has been shown that the sliding optimized design has a positive impact also on the churning power losses. The global winning in terms of reduction of the gear meshing power losses can be assessed in about 50%, depending on the reduction ratio.The new design has been validated by means of experimental tests performed in the internal laboratory of the company. The results have fully validated both the numerical approach and the new design.     

Cardiovascular and cancer risk factors analysis for 2001–2020 from the global research output and European newspapers

Scientometrics - Cancer and cardiovascular disease (CVD) are now two of the leading components of the global burden of disease, especially in high- and upper-middle-income countries. Causes of the...     

On δ-record observations: asymptotic rates for the counting process and elements of maximum likelihood estimation

Given a sequence of random variables {X _n ,n≥1} and δ∈ℝ, an observation X _n is a δ-record if X _n >max {X ₁,…,X _n−1}+δ. We obtain, for δ≤0, weak and strong laws of large numbers for the counting process of δ-records among the first n observations from a sequence of independent identically distributed random variables, with common distribution F, possibly discontinuous. We provide examples of our results in the context of common probability distributions. Finally, we show how δ-records can be used for maximum likelihood estimation.     

A new etching technique for revealing the plastic deformation zone in an Al–Cu–Mg alloy

A new etching technique for revealing the plastic deformation zone in an Al–Cu–Mg alloy has been developed. The etching with the proposed etching agent was conducted on the deformed sample after being heated to 673 K for 3 h. With this etching technique, the plastic deformation zone was clearly observed even under low magnification. This was due to the change of microstructural characteristics in the plastic deformation zone after the heating process, in which there is significant precipitation of Al₂Cu and Mg₂Si, caused by the high energy arising from the severe deformation.     

Surface plastic deformation distribution and microstructural evolution in the compound rolling of Ti–50Al billet

Compound rolling, which uses two different roller profiles to create plastic strain variation in the surface of a material, is described in this study. Based on the local load theory, equipment for the plastic deformation on the surface of the rectangular billet has been produced. The compound rolling behavior of Ti–50Al billet has been studied using this equipment. In order to study the deformation distribution of compound rolling, the flow net method for strain measurement has been employed. The deformation differences between compound rolling and flat rolling have been investigated with the commercial finite element method (FEM) code DEFORM-3D. The microstructure and the hardness from the surface to the center of the Ti–50Al billet developed through compound rolling has been characterized. These results indicate that the compound rolling technique results in severe plastic deformation near the surface with limited strain towards the center of the billet. This can result in compound microstructures, with fine recrystallized grains in the near surface region and the original directionally solidified microstructures in the center, and improve the hardness on the surface of the billet significantly.