Rigidity Values Research Articles

The cyclicality of labor force participation flows: The role of labor supply elasticities and wage rigidity

Using a representative-household search and matching model with endogenous labor force participation, we study the cyclicality of labor market transition rates between employment, unemployment, and nonparticipation. When interpreted through the lens of the model, the cyclical behavior of transition rates implies that the participation margin is strongly countercyclical: the household's incentive to send the workers to the labor force falls in expansions. We identify two key channels through which the model delivers this result: (i) procyclical values of non-market activities and (ii) wage rigidity. The smaller the value of the extensive-margin labor supply elasticity is, the stronger the first channel is. Wage rigidity helps because it mitigates increases in the return to market work during expansions. Our estimated model replicates well the behavior of transition rates between the three labor market states and thus the stocks, once both features are in place.

Experimental testing of slender load-bearing masonry walls with realistic support conditions

Slender, load-bearing masonry walls with slenderness ratios (h/t) greater than 30 are required to be designed as pinned-pinned elements according to North American provisions for masonry, CSA S304-14 and TMS 402-16. This provision neglects the contribution of the reactive stiffness of the foundation to the strength of the wall and its effect on the redistribution of bending moments along its height. Eight full-scale masonry walls were built with different degrees of base stiffness and tested under an eccentric axial load. The results of the tests showed an increased load-bearing capacity and decreased deflections with increased rotational base stiffness. Experimental data were used to determine key design parameters, including the effective flexural rigidity and moment distribution along the height of the walls. Comparing the values of effective flexural rigidity determined from experimental results to code provisions, it was found that both codes tend to underestimate the effective flexural rigidity of the walls.

World grid of cosmic ray vertical cut-off rigidity for the last decade

Cosmic ray cut-off rigidity tables and maps over the world concerning the epochs 2010, 2015 and the current one 2020 have been constructed. These maps display the effective cut-off rigidity in every five degrees in latitude and in longitude at the altitude of 20 km above the surface of the international reference ellipsoid. The values of the geomagnetic cut-off rigidity were calculated in every 5° in latitude and in every 15° in longitude applying the well-known method of particle trajectory calculations resulted from the theory of the particle motion in the Earth's magnetic field. The applied software employed the 12th Generation of the International Geomagnetic Reference Field (IGRF 12) and trajectories were calculated at 0.01 GV intervals in order to determine the vertical cut-off rigidity for each location. Beyond the use of the calculated cut-off rigidity values as a basic reference of charged particle access to different geographical locations during quiet and/or more intense geomagnetic periods, these results can be used for a long- term forecasting of the geomagnetic conditions variations.

Vibroacoustic Assessment of an Innovative Composite Material for the Roof of a Coupe Car

The objective of this paper is the vibroacoustic evaluation of an innovative material for a sports car roof, aiming at replacing fiberglass composite materials. Such evaluation was carried out using numerical and experimental analysis techniques, with cross-comparison between the corresponding results. The innovative material under analysis is a composite material, with a thermoplastic polypropylene matrix and reinforcement made of cellulose fibers. In order to validate the virtual dynamic modeling of the new material, the inertance on different points of some sheets made of the material under analysis was evaluated by an in-house made experimental activity, performed in the CRF (Fiat Research Center) test room, and cross-compared with corresponding results from a numerical analysis performed with the MSC Nastran software. Then, a realistic model of the car roof of the Alfa Romeo 4C car, made with the new material, was implemented and analyzed from the vibroacoustic point of view. The mere switch to the new material, with no changes in the geometry/structure of the car roof, did not allow preserving the original values of static rigidity, dynamic rigidity, and configuration of modal shapes. For this reason, a geometric/structural optimization of the component was performed. Once the new geometry/structure was defined, a vibroacoustic analysis was carried out, checking for a possible coupling between the fluid cavity modes and the structure car body modes. Finally, the vibroacoustic transfer functions to the driver’s ear node were assessed, considering two different excitation points on the structure. The excellent damping capacity of the proposed material led to an improvement in the vibroacoustic transfer functions and to a reduction in the weight of the pavilion.

Surface Texture after Turning for Various Workpiece Rigidities

In the paper, we present an analysis of the surface texture of turned parts with L/D (length/diameter) ratios of 6 and 12 and various rigidity values. The studies were carried out on samples made of S355JR steel and AISI 304 stainless steel. A detailed analysis of 2D surface profiles was carried out by using a large number of parameters that allowed us to distinguish significant differences in the surface microgeometry, which confirmed that determining surface characteristics from one height parameter (Ra—arithmetical mean height) is far from sufficient. The obtained results indicate significantly better roughness and waviness values of the AISI 304 steel surfaces in terms of its size, periodicity, and regularity. Therefore, the turning process of AISI 304 shafts with low rigidity allows one to be able to achieve better quality texture and have a positive effect on the general properties of a workpiece. In all tested samples, surface irregularities decreased along with the distance from the tailstock. The shafts with an L/D ratio of 12 had worse surfaces in the first two sections due to lower rigidity. The results received close to the three-jaw chuck, regardless of the L/D ratio and material type, demonstrated similar waviness and roughness parameters and profiles.

Improving the thermal stability and luminescent efficiency of (Ba,Sr)3SiO5:Eu2+ phosphors by structure, bandgap engineering and soft chemistry synthesis method

The quantum yield and thermal stability are significant properties for phosphors, determining the luminescence efficiency of the devices for indoor lighting, displays backlight and near-infrared (IR) sensor applications. It is well known that the large bandgap and Debye temperature (Structure rigidity) values are beneficial to high thermal resistance. Here, the crystal structure, luminescence, thermal quenching property, bandgap and structural rigidity of (Ba,Sr)3SiO5:Eu2+ were studied via Rietveld refinement, temperature-dependent photoluminescence spectra and first-principle calculations. The quantum yield and thermal stability of (Ba,Sr)3SiO5:Eu2+ were increased by ~17% and 14%, respectively, via the combination of structure and bandgap engineering. These properties were further optimized by sol-gel synthesis process, achieving 28% increase of emission intensity compared to the same composition synthesized by a solid-state method and only 5% loss of luminescence intensity at 150 °C. By adding the as-synthesized phosphors, the correlated color temperature and color rendering index of the LED device were lower and higher, respectively, indicating the potential value in practice.

A numerical analysis on the effect of pile head connections on piled raft foundation subjected to vertical and static horizontal load

A numerical analysis has been performed on the piled raft subjected to uniform vertical load and static horizontal load on piled raft foundation. The applied horizontal load was about 6%, 8%, 9% and 12% of vertical applied load. A constant spacing and uniform length to diameter ratio of 3x3 pile group of piled raft models have been adopted in the present study. These models were validated first and then analysis of adopted finite element models resting on cohesion less soil has been carried out. The rigid and hinged pile head connectivity with raft has been considered. The effect of raft-soil stiffness has been adopted in the study. Normalized axial forces, normalized bending moment and normalized lateral displacement of piles throughout its length have been studied. In the case of rigidly connected piles of piled raft, the maximum positive moment of the piles was reached near the top and the maximum negative moment was found at the middle one-third section of the pile depth. The bending moment at the top was zero in case of hinged connected piles of piled raft and the highest positive moment was reached at one-third portion of pile depth from the top. Furthermore, at the bottom end of the pile it decreased to about zero. The influence of increment of horizontal load on vertically loaded piled raft has been examined too. With an increase in horizontal load from 6% to 12% of applied vertical load, the piled raft with rigid connected piles displaced 8 percent −20 percent lower than the piled raft with hinged connected piles at a constant value of relative raft rigidity.

Evaluation of the Influence of Different Grades of Reinforcing Steel on the Seismic Performance of Concrete reinforced Frame Structures with Nonlinear Static Analysis

In this investigation, the elasto-plastic behavior and the seismic performance of concrete reinforced frame structures reinforced are evaluated by applying the Pushover method. This evaluation is done on several cases: with high ductility steel (Grade 40), conventional steel (Grade 60) and high strength steel (Grade 75). For the previous, the capacity curve graph obtained from the displacement coefficient method was used to measure the capacity of the structure. In addition, the performance of the structure for different levels of seismic design are evaluated with the resulting values of ductility and rigidity of each case. The results showed that reinforcing a structure with a Grade 40 reinforcing steel increases the energy dissipation capacity, and if reinforced with a Grade 75 reinforcing steel increases the strength capacity in the structure. Finally, the comparative result of the various cases are presented to demonstrate the influence of reinforcing steel on the plastic behavior of concrete reinforced frame structures.

Diffuse approximation for identification of the mechanical properties of microcapsules

A novel data-driven real-time procedure based on diffuse approximation is proposed to characterize the mechanical behavior of liquid-core microcapsules from their deformed shape and identify the mechanical properties of the submicron-thick membrane that protects the inner core through inverse analysis. The method first involves experimentally acquiring the deformed shape that a given microcapsule takes at steady state when it flows through a microfluidic microchannel of comparable cross-sectional size. From the mid-plane capsule profile, we deduce two characteristic geometric quantities that uniquely characterize the shape taken by the microcapsule under external hydrodynamic stresses. To identify the values of the unknown rigidity of the membrane and of the size of the capsule, we compare the geometric quantities with the values predicted numerically using a fluid-structure-interaction model by solving the three-dimensional capsule-flow interactions. The complete numerical data set is obtained off-line by systematically varying the governing parameters of the problem, i.e. the capsule-to-tube confinement ratio, and the capillary number, which is the ratio of the viscous to elastic forces. We show that diffuse approximation efficiently estimates the unknown mechanical resistance of the capsule membrane. We validate the data-driven procedure by applying it to the geometric and mechanical characterization of ovalbumin microcapsules (diameter of the order of a few tens of microns). As soon as the capsule is sufficiently deformed to exhibit a parachute shape at the rear, the capsule size and surface shear modulus are determined with an accuracy of 0.2% and 2.7%, respectively, as compared with 2–3% and 25% without it, in the best cases (Hu et al. Characterizing the membrane properties of capsules flowing in a square-section microfluidic channel: Effects of the membrane constitutive law. Phys Rev E 2013; 87(6): 063008). Diffuse approximation thus allows the capsule size and membrane elastic resistance to be provided quasi-instantly with very high precision. This opens interesting perspectives for industrial applications that require tight control of the capsule mechanical properties in order to secure their behavior when they transport active material.

Experimental investigation on flexural behaviour of composite PVC encased macro-synthetic fibre reinforced concrete walls

Composite PVC encased concrete walls provide substantial advantages in terms of structural strength and durability enhancement, ultraviolet radiation and pest infestation resistance, design flexibility, ease of construction and excellent resistance to impact. In this study, the effects of using macro-synthetic fibre reinforced concrete on flexural behaviour of composite PVC encased walls in comparison with composite PVC encased walls filled with conventional plain concrete and reinforced concrete have been experimentally investigated. Fifteen composite PVC encased concrete wall specimens were cast and tested using three-point bending test. Based on the load-deflection curves resulting from the three-point bending tests, flexural parameters including ultimate loads, ultimate flexural strengths, stiffness and flexural rigidity values for cracked and uncracked conditions were determined for three different cases including i) test specimens filled with plain concrete, ii) test specimens filled with macro-synthetic fibre reinforced concrete, and iii) test specimens filled with reinforced concrete. The determined parameters as well as the measured load-deflection curves for the three cases were compared and the final findings have been discussed. Based on this study, it has become apparent that using BarChip 48 macro-synthetic fibre reinforced concrete in composite PVC encased walls instead of plain concrete can lead to 43.5% flexural strength improvement and 25% stiffness enhancement at the age of 28 days. Based on the experimental measurements and theoretical comparison in this study, it has been concluded that composite PVC encased walls filled with BarChip 48 macro-synthetic fibre reinforced concrete, without steel reinforcement, are deemed suitable for sway-prevented structures such as retaining walls. If using steel reinforcement in composite PVC encased retaining walls is not an option due to high-risk of steel corrosion in harsh environment; it is highly recommended that the retaining walls to be filled with macro-synthetic fibre reinforced concrete instead of plain concrete to ensure the safety and structural integrity of this type of sway-prevented structures.

New possibilities for the synthesis of high-molecular weight poly(2,5(6)-benzimidazole) and studies of its solutions in DMSO-based complex organic solvent

New possibilities for the synthesis of high-molecular weight poly(2,5(6)-benzimidazole) (ABPBI) based on a new monomer, 3,4-diaminobenzoic acid monophosphate, in polyphosphoric acid medium at high monomer concentration under stirring and on a Teflon® surface without stirring are investigated. New complex solvent for ABPBI is found. This solvent is based on dimethyl sulfoxide, methanol, and potassium hydroxide. For the first time, molecular weight values are obtained by dynamic light scattering and viscometry in complex solvent. In addition, Kuhn segment values are estimated. Maximal molecular mass MDη value reaches 94 kDa. The values of macromolecular equilibrium rigidity A are estimated as 4.4–5.7 nm according to translational diffusion coefficient and 3.3 nm according to intrinsic viscosity measurements.

Dynamics and buckling loads for a vibrating damped Euler\u2013Bernoulli beam connected to an inhomogeneous foundation

In this paper, the dynamics and the buckling loads for an Euler–Bernoulli beam resting on an inhomogeneous elastic, Winkler foundation are studied. An analytical, asymptotic method is proposed to determine the stability of the Euler–Bernoulli beam for various types of inhomogeneities in the elastic foundation taking into account different types of damping models. Based on the Rayleigh variation principle, beam buckling loads are computed for cases of harmonically perturbed types of inhomogeneities in the elastic foundation, for cases of point inhomogeneities in the form of concentrated springs in the elastic foundation, and for cases with rectangular inclusions in the elastic foundation. The investigation of the beam dynamics shows the possibility of internal resonances for particular values of the beam rigidity and longitudinal force. Such types of resonances, which are usually typical for nonlinear systems, are only possible for the beam due to its inhomogeneous foundation. The occurrence of so-called added mass effects near buckling instabilities under the influence of damping have been found. The analytical expressions for this “added mass” effect have been obtained for different damping models including space hysteresis types. This effect arises as a result of an interaction between the main mode, which is close to instability, and all the other stable modes of vibration.

Surface active monomers: from micellar solution properties to molecular characteristics

Hydrodynamic methods and light scattering were used in the studies of solutions of a surface active monomer 11-acryloyloxyundecyltrimethylammonium bromide (AUTA-Br) and its polymers in 0.05 M NaCl. Aqueous solutions of AUTA-Br monomer in the concentration range of 4 to 16 CMC contain individual molecules and near-spherical AUTA-Br aggregates. The pAUTA-Br polymers possess rather high equilibrium rigidity (11.8 nm). This high value of equilibrium rigidity found for pAUTA-Br macromolecules is apparently caused by two factors: the presence of a bulky side substituent in each AUTA-Br monomer unit and incomplete suppression of electrostatic interactions between neighboring monomer units in the backbone.

Development and characterisation of cytocompatible polyester substrates with tunable mechanical properties and degradation rate

Although it has been repeatedly indicated the importance to develop implantable devices and cell culture substrates with tissue-specific rigidity, current commercially available products, in particular cell culture substrates, have rigidity values well above most tissues in the body. Herein, six resorbable polyester films were fabricated using compression moulding with a thermal presser into films with tailored stiffness by appropriately selecting the ratio of their building up monomers (e.g. lactide, glycolide, trimethylene carbonate, dioxanone, ε-caprolactone). Typical NMR and FTIR spectra were obtained, suggesting that the fabrication process did not have a negative effect on the conformation of the polymers. Surface roughness analysis revealed no apparent differences between the films as a function of polymer composition. Subject to polymer composition, polymeric films were obtained with glass transition temperatures from -52 °C to 61 °C; contact angles in water from 81 ° to 94 °; storage modulus from 108 MPa to 2,756 MPa and loss modulus from 8 MPa to 507 MPa (both in wet state, at 1 Hz frequency and at 37 °C); ultimate tensile strength from 8 MPa to 62 MPa, toughness from 23 MJ/m3 to 287 MJ/m3, strain at break from 3 % to 278 %, macro-scale Young's modulus from 110 MPa to 2,184 MPa (all in wet state); and nano-scale Young's modulus from 6 kPa to 15,019 kPa (in wet state). With respect to in vitro degradation in phosphate buffered saline at 37 °C, some polymeric films [e.g. poly(glycolide-lactide) 30 / 70] started degrading from day 7 (shortest timepoint assessed), whilst others [e.g. poly(glycolide-co-ε-caprolactone) 10 / 90] were more resilient to degradation up to day 21 (longest timepoint assessed). In vitro biological analysis using human dermal fibroblasts and a human monocyte cell line (THP-1) showed the potential of the polymeric films to support cell growth and controlled immune response. Evidently, the selected polymers exhibited properties suitable for a range of clinical indications.

Measuring Gaussian Rigidity Using Curved Substrates.

The Gaussian (saddle splay) rigidity of fluid membranes controls their equilibrium topology but is notoriously difficult to measure. In lipid mixtures, typical of living cells, linear interfaces separate liquid ordered (LO) from liquid disordered (LD) bilayer phases at subcritical temperatures. Here, we consider such membranes supported by curved substrates that thereby control the membrane curvatures. We show how spectral analysis of the fluctuations of the LO-LD interface provides a novel way of measuring the difference in Gaussian rigidity between the two phases. We provide a number of conditions for such interface fluctuations to be both experimentally measurable and sufficiently sensitive to the value of the Gaussian rigidity, while remaining in the perturbative regime of our analysis.

The Role of the Shell Structure in the Formation of Surface Tension in Atomic Nuclei

The surface tension coefficients $$\sigma$$ of even–even nuclei with $$10<A<212$$ were estimated by using their dependence on the nuclear rigidity. The values of the nuclear rigidity were calculated based on the data on the mean squared deformation of nuclei. The correlation of the values of $$\sigma$$ with the structure of the neutron and proton subshells was investigated. The connection of the surface tension with the nuclear deformation was revealed.

Hydrodynamic Forces on a Submerged Horizontal Circular Cylinder in Uniform Finite Depth Ice Covered Water

Hydrodynamic forces on a submerged cylinder in uniform finite depth ice-covered water is formulated by using the method of multipoles, the ice-cover being modelled as an elastic plate of very small thickness. The forces (vertical and horizontal) are obtained analytically as well as numerically and depicted graphically for various values of flexural rigidity of the ice-cover to show the effect of its presence. When the flexural rigidity and surface density of the ice-cover are taken to be zero, then the curves for the forces almost coincide with the curves for the case of uniform finite depth water with free surface.

The effects of sol–gel coatings doped with zinc salts and zinc oxide nanopowders on multifunctional performance of linen fabric

In this study, it was aimed to provide multifunctional performance characteristics like ultraviolet protection, antibacterial activity and antiwrinkle effect on linen fabrics in one process by sol–gel coatings doped with different zinc chemicals. In addition, the effects of nano-sized zinc oxide nanopowders and micro-sized zinc salts were also discussed and compared. As control samples, both unfinished and pure silica coated (undoped) linen samples were used and as sol–gel coatings, ten sol–gel coatings were prepared with zinc salts (zinc acetate, zinc nitrate and zinc sulphate) and zinc oxide nanopowders. The coatings were applied to linen fabrics by pad-dry-cure method. Then, add on % values, ultraviolet protection factors, antibacterial properties, wrinkle recovery angles, tensile strength and elongation at break values, bending length and bending rigidity values and whiteness–yellowness values were determined according to the standard test methods. The coating film layer on the fiber surfaces and elemental content of the coatings were evaluated by scanning electron microscopy and energy dispersive X-ray analysis respectively. Fourier transform infrared (FTIR-ATR) analysis was used to determine the changes in chemical structures of the linen fabric samples after finishing processes and X-ray diffraction analysis was performed to characterize the zinc oxide nanopowders. As a result of the study, antiwrinkle effect, antibacterial activity and ultraviolet protection effect could be improved in one process and in terms of physical properties no considerable changes were observed. From the point of functional efficiency, nano-sized zinc oxide nanopowders were more favorable than micro-sized zinc salts.

Selecting Appropriate Longitudinal Rigidity of Knitted Fabric in Compression Products of Standardised Size

Based on the models developed, the changes in unit pressure exerted by ready-made compression products were evaluated in dependence on the longitudinal rigidity, compression class, dimensional tolerance and product size. Tests made it possible to determine the maximum permissible values of longitudinal rigidity for individual compression classes and product sizes, which, if not exceeded, ensure that the pressure exerted falls within the given compression class. Experimental verification carried out on an example of a commercial compression product from the first and second compression classes showed that the main reason for the differences between the declared and experimentally determined values of unit pressure was the overestimated longitudinal rigidity of the knitted fabric and dimensional tolerance of the size ranges and errors in the design procedure, resulting from not sticking to the principle of designing the product for the middle circumference value and the middle pressure from the compression class.

Utilization of hall current and ions slip effects for the dynamic simulation of peristalsis in a compliant channel

The recent hypothetical analysis is to explore the effect of hall current and ion's slip for a peristaltic mechanism of non-Newtonian Rabinowitsch fluid model (lubricant blended with the viscosity index reformer) with the dynamic damping and stiffness features. The mathematical model is examined by considering the assumptions of low Reynold's number and long wavelength, the governing system of non-linear differential equations are solved with the help of the perturbation technique. The impact of numerous parameters associated with a fluid flow such as viscous damping, stiffness, rigidity, Hall parameter and Brickman number are intrigued for velocity profile, temperature distribution, and concentration profile. Results are strategized and deliberated for shear thickening, shear-thinning, and a viscous fluid model. It is observed that the momentum distribution is enhanced for larger values of stiffness, rigidity and viscous damping force parameters, but quite reverse nature is depicted for thermal distribution. The variations of streamline are presented graphically for the Hartman number and elastic parameters. Brinkman number is related to the viscous dissipation effects, so it contributes to enhancing the thermal distribution of fluid for all cases.