Dependence Of Strength Research Articles

Dependence of Bending Strength on Length and Diameter of Sapphire Fibers Grown by the Stepanov Technique

Dependence of Bending Strength on Length and Diameter of Sapphire Fibers Grown by the Stepanov Technique

Radiobiological evaluation of the stepping-source effect in single-fraction monotherapy high-dose-rate prostate brachytherapy

The continued reliance upon the traditional biologically effective dose (BEDT) formalism of BEDT=nd(1+d/(α/β)) may be one possible contributor to the poor clinical outcomes observed with single-fraction 19-20 Gy prescriptions in prostate high-dose-rate (HDR) brachytherapy because BEDT does not consider intrafraction sublethal damage repair (iSLDR). This, along with low α/β and repair half-times comparable to delivery time, could reduce the biological effect predicted using BEDT. BED was recalculated with a model accounting for iSLDR, using time-averaged uniform dose rate (BEDg1) patterns and time-variable dose rate (BEDgss) patterns inherent to stepping-source delivery. An assortment of two-pulse delivery sequences assuming 19 Gy in 972 s was analyzed. Calculations were repeated for 17470 and 61050 U to investigate source strength dependence. BEDg1 and BEDgss was/were lower than BEDT by 16.9% and 11.1%-21.1%, respectively, for 40700 U. For 17470 U, BEDg1 and BEDgss was/were lower than BEDT by 32.5% and 21.5%-37.1%, respectively. For 61050 U, BEDg1 and BEDgss was/were lower than BEDT by 11.9% and 7.8%-15.3%, respectively. BEDgss was most dependent on pulse spacing with milder dependence on pulse onset time. BEDg1 served as a lower bound approximation of BEDgss for fast effective delivery time. Even for points with the same calculated dose, the biological dose was significantly reduced by iSLDR (as much as 37.1%). While BEDgss explicitly addressed the temporally-variable dose rate inherent to a stepping-source delivery, calculations were cumbersome. Under certain conditions, BEDg1 may serve as an approachable method to quickly assess "worst-case scenario" BED.

Parallel multi-slit modulation and decoding technique for high-resolution surface measurement in structured illumination microscopy

Optically-sectioned structured illumination microscopy (OS-SIM) is an important tool for biological imaging and engineering surface measurements. However, in the current OS-SIM systems, the dependence of the sectioning strength on illumination pattern frequency hinders the achievement of consistent high axial resolution for various surface topography measurements. In this paper, we develop a parallel multi-slit modulation and decoding technique for OS-SIM, called PMMD-OS-SIM, to solve the existing dependence problem. Specifically, a set of high-contrast parallel multi-slit illumination patterns are projected onto the sample to modulate the surface height information. And then, a specially-designed decoding algorithm is applied to the modulated patterns for high-quality optical sectioning. By effectively combining the above modulation and decoding techniques, the optical-sectioning strength of PMMD-OS-SIM is decoupled from the illumination pattern frequency, thereby facilitating consistent high-resolution measurements for a wide range of surface topographies. The validity of the proposed method is demonstrated by measurement experiments performed on various test samples.

Water content effects on the strain-rate-dependent dynamic response of fine-grained and coarse-grained sandstones

In deep-mining engineering, water inrush accidents induced by dynamic disturbance were often controlled by the formation of the inrush channel (mainly caused by crack coalescence). It always originated from the microcrack growth and coalescence from the mineral-grain scales and can be influenced by the loading rates. Therefore, this paper selected fine-grained (fine grain) and coarse-grained (coarse grain) sandstones and conducted the dynamic split Hopkinson pressure bar (SHPB) tests with high-speed cameras. Moreover, the microcrack evolution was identified by the optical microscopy that can observe the true microcrack generation and propagation. The results show that water content can weaken the dynamic compressive strength of sandstones and contribute to the rate dependence of strength and energy dissipation, and moreover the coarse grain samples represent a more obvious trend (ε˙ = 40–160s−1). In addition, the box dimension was introduced to calculate the fractal dimension and built the quantitative relationship between mesodamage variable and fractal dimension to identify the microcrack evolution. It can offer a new method to understand the influenced mechanism of water content on the rate dependence of mechanical response from a multi-scale analytical framework.

Dependence of corn kernel strength on moisture

BACKGROUND:Moisture has an essential role at threshing of breeding material of corn, as when mois-ture is too low (material is dry) shattering of corn seed takes place while threshing and seed material becomes inapplicable to use, whereas increased moisture leads to underthreshing and microtraumas, invisible to the na-ked eye, that significantly reduces germination of the breeding material.
 AIMS:To define dependence of corn kernel strength on moisture, to carry out an experiment to identify kernel fracture force.
 METHODS:In this study the analysis of scientific researches, made by such scientists as G.K. Takoev, M.G. Golikov and N.S. Buddo who established dependences of corn shattering while corn cob threshing on corn moisture was carried out. The experimental data on study of corn kernel strength with various moisture at threshing by the Rostselmash NOVA 330 and the Claas Mega 370 combine harvesters is presented in the arti-cle and obtained with use of an oscillograph. Corn moisture has a significant impact on cob threshing quality. The scheme of the screw press, used for defining kernel fracture force, is shown in the article.
 RESULTS:It is established that productive capacity of corn threshers reduces with increase of kernel moisture in cobs, leading to complication of threshers design. The experiments revealed that the kernel of the Krasnodarsky 425 MV hybrid corn with the moisture of 18.21% can withstand the average load of 108 N, whereas with the moisture of 29.28% the fracture force reduces to 90-100 N.
 CONCLUSIONS:With the analysis of the obtained experimental data and after plotting corresponding graphs, it is proved that kern strength increases with corn kernel moisture decrease from 30% to 17%.

OPTIMIZING POROUS MATERIALS WITH PREDICTION THERMAL PHYSICAL CHARACTERISTICS

The article presents experimental data, based on which the influence of various factors on the strength and thermophysical characteristics of porous heat-insulating materials was studied.
 Porous bodies in thermal power engineering are used for thermal protection of power plants, various aggregates, in thermal insulation structures of buildings and technological networks. The properties of these materials and the field of use depend on their chemical composition and method of production.
 The task of this research is to obtain a raw material mixture for heat-insulating material of the closed-cell type with increased thermal resistance and porosity by optimizing its qualitative and quantitative composition. The goal is also to improve the method of obtaining porous heat-insulating material by changing the temperature and time regimes in order to improve the physical, mechanical and operational characteristics, which will allow the material to be used in a wider temperature range.
 Based on the dependences of strength and thermophysical properties on the density of the finished material obtained in the work, it was concluded that the best characteristics are the samples of the porous material with the lowest density, which are formed at the maximum humidity of the raw material. Kinetics of drying and heat treatment of the raw material mixture, thermal regimes are the main factors that determine the porosity, strength and thermal conductivity of the finished heat-insulating material.
 Performed laboratory studies of the material proposed in the paper allow choosing the required temperature regimes of heat treatment. Thus, the task of further research is to choose a method of organizing effective heat and mass exchange, modeling these processes, experimental testing of the obtained data, and creating a method for determining the main technological and structural parameters of the method of obtaining a new material.
 The performed experimental studies made it possible to determine the conditions for the implementation of new technologies for the production of porous materials with the possibility of predictive determination of their properties.

Effects of Diffusible Hydrogen on Fatigue Life of Spot Welds in High-tensile-strength Steel Sheets

Spot-welded advanced high-strength steel (AHSS) sheets are used to decrease car body weight and enhance crashworthiness simultaneously. Such welds are susceptible to hydrogen embrittlement, but research in this area is limited. We have evaluated the hydrogen embrittlement properties of spot welds fabricated with AHSS sheets and clarified the dependence of diffusible hydrogen content and tensile rate on tensile shear strength. However, the performance of spot welds must be evaluated not only by static testing such as tensile shear tests but also by dynamic fatigue testing. Herein, we investigated the effects of diffusible hydrogen on their fatigue life via tensile–shear fatigue tests under cathodic hydrogen charging. The number of cycles to failure and the endurance limit decreased with diffusible hydrogen content. The number of cycles to failure decreased as the constant amplitude-loading frequency declined. The intergranular cracking is more likely to occurs as the amount of diffusible hydrogen increases and as the frequency decreases. These results are explained by hydrogen accumulation and crack growth behavior caused by mechanism for hydrogen-enhanced local plasticity and hydrogen enhancement of the strain-induced generation of vacancies mechanism. Furthermore, the correlation between static testing and dynamic fatigue testing was investigated, and the relationship between fatigue strength and the amount of diffusible hydrogen was in good agreement with the diffusible hydrogen dependence of tensile shear strength obtained from slow rate tensile shear tests under hydrogen charging.

Construction and technical properties of vermiculite concrete and fibro vermiculite concrete with volcanic pumice under the influence of elevated temperatures

Objective. Development of compositions of vermiculite concrete and fibro vermiculite concrete with volcanic pumice. Investigation of the construction and technical properties of the developed compositions of vermiculite concrete and fibrovermiculite concrete with volcanic pumice under the influence of elevated temperatures.Method. Methods of increasing the fire resistance of reinforced concrete structures are considered. The research is aimed at the development of vermiculite concrete and fibro vermiculite concrete with volcanic pumice for fire protection of building structures and the manufacture of heat-resistant products and structures. To reduce the cost of vermiculite concrete, its partial replacement with volcanic pumice is proposed. For the study of vermiculite concrete with volcanic pumice reinforced with basalt fiber, a rotatable plan of the second order of the regular hexagon type was used.Result. Replacing a part of an expensive aggregate (expanded vermiculite) with pumice leads to a slight increase in the average density of the composite, while the bending and compressive strength increases. In addition, the heat-resistant properties of vermiculite concrete with pumice are increased. This is due to the fact that volcanic pumice, being a hydraulically active additive, is able to react hydration with cement components, eliminating the harmful effect of secondary hydration of free calcium oxide. The influence of the heating temperature on the change in the construction and technical properties of vermiculite concrete and fibrovermiculic concrete, including with the addition of pumice, has been studied. It was found that dispersed reinforcement with basalt fibers reduces shrinkage deformations, when heated to t = 800, the shrinkage decreases from 0.7 to 0.5% compared to the original concrete matrix.Conclusion. The dependence "compressive strength = f (average concrete density)" significantly depends on the presence and ratio of pumice in the composition of vermiculite concrete, while an increase in the holding temperature to 600 oC or 800 oC leads to a decrease in the compressive strength from 15 to 25%, and the main decrease occurs when heated to 600 oC, further the increase in temperature has a negligible effect. The dependence of the bending strength on the compressive strength is generally maintained regardless of the heating temperature, and the heating of concrete does not reduce the relative bending strength, i.e. the ratio of bending strength / compressive strength is not reduced. Dispersed fiber reinforcement increases the relative bending strength by about 70% regardless of the heating temperature.

Identifying the structure patterns to govern the performance of localization in regulating innovation diffusion

The macro social influence is recognized as a non-negligible ingredient in innovation propagation: more adopters in the network lead to a higher adoption tendency for the rest individuals. A recent study to incorporate such a crucial mechanism shows that sufficient intensity of macro-level social influence can cause a change from a continuous to discontinuous transition, further indicating the existence of a tricritical point. Although network localization strength determines the tricritical point, it remains unclear what network quantities govern the performance of localization in regulating innovation diffusion. To address this issue, we herein consider the model incorporating both the micro- and macro-levels social influence. We present a dynamic message-passing method to analytically treat both the outbreak threshold and recovered population, and validate the predictions through agent-based simulations. Extensive analysis on the classical synthetic networks shows that sparsely available connections, and relatively heterogeneous degree distribution, either assortative or extremely disassortative configurations are favorable for continuous transition. In such cases, the employed network can yield a strong localization effect so that the innovation is trapped in the configurations composed of the hubs with high non-backtracking centrality. We further explore the dependence of both tricritical point and localization strength on three structural quantities: network density, heterogeneity, and assortativity, which gives a clear physical picture of the joint effects of the three structure quantities on the localization strength. Finally, we conclude that the core-periphery structure, being sensitive to the change of the three structure quantities, essentially determines localization strength, and further regulates the phase transition.

Optimization of inductive fast-curing of epoxy adhesive by model-based kinetics

Adhesively bonded joints must be fixed until a necessary degree of cure is reached. This is done by hybrid joining processes or fixing methods that hold the bonded parts in position. Inductive fast-curing can enable time-efficient processes without additional joining methods, but the complexity of the process and the variety of influencing factors make it challenging to develop. In this work, a new approach to the design of fast-curing processes is pursued, which, in addition to classical temperature measurements, relies on real-time simulation of the curing degree, providing direct feedback on the quality of the induction parameters set. DSC measurements were performed on a single-component epoxy adhesive, which were used to develop kinetics models according to model-free and model-based methods. Fast curing tests show the dependence of initial strength on temperature and degree of conversion, with a comparison of experimentally and numerically determined degrees of conversion revealing high agreement. The demonstrated suitability of the kinetics model allowed fast-curing processes to be optimized using a developed tool for real-time conversion degree determination, such that a high initial strength was achieved even with different joining part materials. FEM simulations also reveal the effect of temperature gradients due to uneven heating, which leads to conversion gradients in the adhesive layer that must be avoided.

Stress-Dependent Shear Strength of Resedimented Nile Silty Clay

The variation of clay undrained shear strength with consolidation stresses is of paramount importance to geotechnical engineers. For several decades, the normalized shear strength of clays has been the cornerstone of geotechnical design in many applications, such as staged construction of embankments. Recently, different trends of shear strength dependency on consolidation stresses have emerged indicating nonlinear variation. Resedimentation has been a useful and reliable method to investigate stress dependency by generating lab test specimens of fine-grained soils with a minimum sample to sample variation for benchmark studies. Previous work on resedimented Nile silty clay (RNSC) has shown unique features, such as high sand fraction and contradicting index properties used for soil classification. The shear strength of Nile silty clay (NSC) and the effects of the consolidation stresses are explored through a laboratory program on resedimented samples from material excavated within the Nile River flood plains. A portion of the material was processed using mechanical energy, which exhibited a significant increase in the liquid limit and a larger clay-sized fraction of particles from grain-size distribution tests. The measured engineering parameters are compared with comparable studied soils and established empirical correlations to provide insights on mechanical behaviors of the NSC. NSC is found to have a rapid decrease in the undrained shear strength ratio and a rapid increase in the lateral stress ratio with increasing consolidation stress.

АЛГОРИТМ ВИБОРУ БІТУМУ ПІД ЧАС ПРОЄКТУВАННЯ КОНСТРУКЦІЇ ДОРОЖНЬОГО ОДЯГУ

Introduction. Asphalt concrete is the most common material for arranging road pavement layers. The significant advantages of asphalt concrete include high performance characteristics, relatively high technical indicators, suitability for regeneration, etc. At the same time, asphalt concrete also has disadvantages, one of which is the significant dependence of strength and deformation characteristics on ambient temperature. Problem statement. Currently, there are no clear criteria for the selection of bitumen in Ukraine that would take into account the conditions of asphalt concrete in the design of pavement structure, but the first steps are already being taken in this direction. The purpose of this work was to practically determine the required properties of bitumen in accordance with the previously proposed algorithms. Objective. Practical determination of the required properties of bitumen in accordance with the previously proposed algorithms. Materials and methods. Analysis of the algorithm for determining the required properties of bitumen, climatic conditions of asphalt concrete and calculation of the required bitumen grade when designing a pavement structure. Results. Suggestions for improving the algorithm for selecting bitumen when designing a pavement structure are provided. An analysis of the climatic conditions of asphalt concrete operation and the calculation of the required bitumen grade according to performance indicators when designing a pavement structure for a conditional road section were performed. A system for selecting bitumen by penetration classification based on established performance indicators is proposed. Conclusions. The proposed algorithm for determining the required bitumen grade when designing a pavement structure can be used to determine the bitumen grade both by performance and penetration classification.

Electromagnetic response of cuprate superconductors with coexisting electronic nematicity

ABSTRACT The electronically nematic order has emerged as a key feature of cuprate superconductors, however, its correlation with the fundamental properties such as the electromagnetic response remains unclear. Here the nematic-order state strength dependence of the electromagnetic response in cuprate superconductors is investigated within the framework of the kinetic-energy-driven superconductivity. It is shown that a significant anisotropy of the electromagnetic response is caused by the electronic nematicity. In particular, in addition to the pure d-wave component of the superconducting gap, the pure s-wave component of the superconducting gap is generated by the electronic nematicity, therefore there is a coexistence and competition of the d-wave component and the s-wave component. This coexistence and competition leads to that the maximal condensation energy appears at around the optimal strength of the electronic nematicity, and then decreases in both the weak and strong strength regions, which in turn induces the enhancement of superconductivity, and gives rise to the dome-like shape of the nematic-order state strength dependence of the superfluid density.

Circuit quantum electrodynamics with a quadruple quantum dot

In this theoretical work, we describe a mechanism for the coupling between a plane structure consisting of four quantum dots and a resonator. We systematically study the dependence of the quadruple coupling strength and the qubit decoherence rate and point out the optimized operating position of the hybrid system. According to the transmission given by the input–output theory, the signatures in the resonator spectrum are predicted. Furthermore, based on the parameters already achieved in previous works, we prove that the device described in this paper can achieve the strong coupling limit, i.e., this approach can be used for system extension under the existing technical conditions. Our results show an effective and promotable approach to couple quantum dot structures in plane with the resonator and propose a meaningful extension method.

Effect of Homogenization Treatment of Raw Milk on the Rheological Properties of Gouda Type Cheese during the Ripening Period

The effects of homogenization treatment of raw milk on the physical properties of the produced Gouda-type cheeses were determined using rheological techniques. In this study, cheese samples were produced using well-controlled raw milk and production methods with and without the homogenization of raw milk. The fracture strength and frequency dependence of the dynamic modulus of the cheese samples were measured immediately after production until eight weeks of ripening. Both the fracture strength and modulus were lower immediately after production in samples homogenized than in samples with no homogenization. The rheological properties of the cheese samples varied throughout the ripening period, but especially around the 10th day of ripening, they showed irregular changes, suggesting that some changes occurred in the microstructure of the cheese during this period. These results suggests that the homogenization treatment of raw milk caused some changes in the structure of casein micelles and their network structures.

THE FORMATION FEATURES OF PIPES STRENGTH CHARACTERISTICS MADE OF MASS GRADES OF AUSTENITIC STAINLESS STEELS AT ROOM AND ELEVATED TEMPERATURES

As part of the research on the development of a new standard for welded and seamless stainless steel pipes, the microstructure, phase composition and mechanical properties in the temperature range of 20-650 °C of pipe samples from austenitic chromium-nickel steels of the Fe-18Cr-10Ni family were evaluated. Significant spread of mechanical characteristics is shown, a quantitative assessment of the contribution of various hardening factors is carried out. It is noted that grain size and solid-solution hardening with carbon, nitrogen or titanium have the most significant effect on mechanical properties, providing up to 45% of the yield strength of steel. It is established that the temperature dependence of the tensile strength is determined by the resistance to the formation of deformation martensite and the intensity of the action of dynamic deformation aging.

Ion Conduction Mechanisms in Potassium Channels Revealed by Permeation Cycles.

Potassium channels are responsible for the selective yet efficient permeation of potassium ions across cell membranes. Despite many available high-resolution structures of potassium channels, those conformations inform only on static information on the ion permeation processes. Here, we use molecular dynamics simulations and Markov state models to obtain dynamical details of ion permeation. The permeation cycles, expressed in terms of selectivity filter occupancy and representing ion permeation events, are illustrated. We show that the direct knock-on permeation represents the dominant permeation mechanism over a wide range of potassium concentrations, temperatures, and membrane voltages for the pore of MthK. Direct knock-on is also observed in other potassium channels with a highly conserved selectivity filter, demonstrating the robustness of the permeation mechanism. Lastly, we investigate the charge strength dependence of permeation cycles. Our results shed light on the underlying permeation details, which are valuable in studying conduction mechanisms in potassium channels.

Parametric amplification in coupled nonlinear waveguides: The role of coupling dispersion

We present the theory of parametric amplification in coupled nonlinear waveguides considering the frequency dependency of the coupling strength. We show that coupling dispersion can indeed compensate for the uncoupled individual waveguides dispersion enabling a substantial tailoring of the gain spectrum. Our theory describes both phase-sensitive and phase-insensitive operational modes, it can be straightforwardly generalized to include arbitrary higher-order waveguide and coupling dispersion and its predictions agree very well with numerical simulations both in the presence and in the absence of waveguide losses. It provides a tool for the design of novel versatile parametric amplifiers based both on coupled integrated waveguides and dual-core fibers too.

Enhanced and reduced solute transport and flow strength in salt finger convection in porous media

We report a pore-scale numerical study of salt finger convection in porous media, with a focus on the influence of the porosity in the non-Darcy regime, which has received little attention in previous research. The numerical model is based on the lattice Boltzmann method with a multiple-relaxation-time scheme and employs an immersed boundary method to describe the fluid–solid interaction. The simulations are conducted in a two-dimensional, horizontally periodic domain with an aspect ratio of 4, and the porosity ϕ is varied from 0.7 to 1, while the solute Rayleigh number R a S ranges from 4 × 10 6 to 4 × 10 9. Our results show that, for all explored R a S, solute transport first enhances unexpectedly with decreasing ϕ and then decreases when ϕ is smaller than a R a S-dependent value. On the other hand, while the flow strength decreases significantly as ϕ decreases at low R a S, it varies weakly with decreasing ϕ at high R a S and even increases counterintuitively for some porosities at moderate R a S. Detailed analysis of the salinity and velocity fields reveals that the fingered structures are blocked by the porous structure and can even be destroyed when their widths are larger than the pore scale, but become more ordered and coherent with the presence of porous media. This combination of opposing effects explains the complex porosity dependencies of solute transport and flow strength. The influence of porous structure arrangement is also examined, with stronger effects observed for smaller ϕ and higher R a S. These findings have important implications for passive control of mass/solute transport in engineering applications.

Thermal Effects on Shear Characteristics of Unbound Granular Materials under Drained Conditions

In this study, the thermally induced changes in the shear characteristics of unbound granular materials (UGMs) were investigated. A series of drained shear tests were conducted using a large-scale triaxial apparatus under controlled temperatures. The thermal dependence of the peak strength, critical strength, internal friction angle, and dilatancy of UGMs were investigated under different temperatures, initial mean effective stresses, and relative compaction. Dense UGMs tended to expand during heating and slightly contract during cooling. In the heating and cooling process, a nonlinear relationship was observed between thermal deformation and temperature. Thermal deformation was attributed to the deformation, movement, and rotation of soil particles and closely related to the initial mean effective stress and relative compaction. A thermal softening effect was observed during the shear test, and the peak strength decreased with increasing temperature. However, negligible thermal effects were observed relative to residual strength. The effect of temperature on the shear characteristics of UGMs was primarily related to the thermal expansion of pores in the soil skeleton. The relationship between peak strength and initial thermal volumetric strain was found to be exponential. Considering the thermal effect, a normalized semi-empirical model of the parabolic Hvorslev envelope for dense UGMs was proposed to supply guidelines for road base design.