• Nuclear Engineering and Technology
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• v.49 no.6
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• pp.1318-1325
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• 2017

Direct Numerical Simulation (DNS) serves as an irreplaceable tool to probe the complexities of multiphase flow and identify turbulent mechanisms that elude conventional experimental measurement techniques. The insights unlocked via its careful analysis can be used to guide the formulation and development of turbulence models used in multiphase computational fluid dynamics simulations of nuclear reactor applications. Here, we perform statistical analyses of DNS bubbly flow data generated by Bolotnov ($Re_{\tau}=400$) and LueTryggvason ($Re_{\tau}=150$), examining single-point statistics of mean and turbulent liquid properties, turbulent kinetic energy budgets, and two-point correlations in space and time. Deformability of the bubble interface is shown to have a dramatic impact on the liquid turbulent stresses and energy budgets. A reduction in temporal and spatial correlations for the streamwise turbulent stress (uu) is also observed at wall-normal distances of $y^+=15$, $y/{\delta}=0.5$, and $y/{\delta}=1.0$. These observations motivate the need for adaptation of length and time scales for bubble-induced turbulence models and serve as guidelines for future analyses of DNS bubbly flow data.

• Geomechanics and Engineering
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• v.18 no.6
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• pp.615-626
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• 2019

Lightweight concrete (LWC) provides an attractive alternative to conventional piles by improving the durability of deep foundations. In this paper, the drivability of cylindrical and tapered piles made of lightweight and common concrete (CC) under hammer impacts was investigated by performing field tests and numerical analysis. The different concrete mixtures were considered to compare the mechanical properties of light aggregate which replaced instead of the natural aggregate. Driving tests were also conducted on different piles to determine how the pile material and geometric configurations affect driving performance. The results indicated that the tapering shape has an appropriate effect on the drivability of piles and although lower driving stresses are induced in the LWC tapered pile, their final penetration rate was more than that of CC cylindrical pile under hammer impact. Also by analyzing wave propagation in the different rods, it was concluded that the LWC piles with greater velocity than others had better performance in pile driving phenomena. Furthermore, LWC piles can be driven more easily into the ground than cylindrical concrete piles sometimes up to 50% lower hammer impacts and results in important energy saving.

• Structural Monitoring and Maintenance
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• v.6 no.3
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• pp.255-268
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• 2019

Civil infrastructures, such as bridges and tunnels are most important assets and their failure during service will have significant economic and social impact in any country. Behavior of a bridge can be evaluated only through actual monitoring/measurements of bridge members under the loads of interest. Theoretical analysis alone is not a good predictor of the ability of a bridge. In some cases, theoretical analyses can give less effect than actual since theoretical analyses do not consider the actual condition of the bridge, support conditions, level of corrosion and damage in members and connections etc. Hence actual measurements of bridge response should be considered in making decisions on structural integrity, especially in cases of high value bridges (large spans and major crossings). This paper describes in detail the experimental investigations carried out on an open web type steel railway bridge. Strain gages and displacement transducers were installed at critical locations and responses were measured during passage of locomotives. Stresses were evaluated and extrapolated to maximum design loading. The responses measured from the bridge were within the permissible limits. The methodology adopted shall be used for assessing the structural integrity of the bridge for the design loads.

• Structural Engineering and Mechanics
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• v.70 no.1
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• pp.33-41
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• 2019

The influence of two parameters on fatigue damage predictions of a variably loaded cantilever beam has been examined. The first parameter is the geometry of the cantilever beam and the weld connecting it to a rear panel. Variables of the geometry examined here include the cantilever length, the weld width on the critical cross-section and the angle of the critical cross-section. The second parameter is the safety factor, as set out by the Eurocode 3 standard. An analytical approach has been used to calculate the stresses at the critical cross-section and standard rainflow counting has been used for the extraction of the load cycles from the load history. The results here suggest that a change in the width and angle of the critical cross-section has a non-linear impact on the fatigue damage. The results also show that the angle of the critical cross-section has the biggest influence on the fatigue damage and can cause the weld to withstand fatigue better. The second parameter, the safety factor, is shown to have a significant effect on the fatigue damage calculation, whereby a slight increase in the endurance safety factor can cause the calculated fatigue damage to increase considerably.

• Proceedings of the Korean Society of Crop Science Conference
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• 2018.10a
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• pp.179-179
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• 2018

Potato (Solanum tubersosum L.) is susceptible to various environmental stresses such as salt, high temperature, and drought. Especially, potato tuber growth is greatly affected by drought that causes not only yield reduction but also loss of tuber quality. Since unpredictable global weather changes cause more severe and frequent water limiting conditions, improvement of potato drought tolerance can minimize such adverse effects under drought and can impact on sustainable potato production. Genetic engineering can be utilized to improve potato drought tolerance, but such approaches using endogenous potato genes have rarely been applied. We were obtained AtbZIP28 gene transgenic potato plants. It is identified transcript levels at various stress conditions, polyethylene glycol (PEG), NaCl, (ABA). Also, For identification to regulate ER stress response genes in AtbZIP28 gene transgenic potato plant, we screened seven potato genes from RNA-seq analysis under TM treatment. Five and two genes were up- and down-regulated by TM, respectively. Their expression patterns were re-examined at stress agents known to elicit TM, DTT, DMSO and salt stress.

• Geomechanics and Engineering
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• v.24 no.3
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• pp.267-280
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• 2021

The research presented in this paper deals with dynamic stability analysis of the graphene nanoplatelets (GPLs) reinforced composite spinning disk. The presented small-scaled structure is simulated as a disk covered by viscoelastic substrate which is two-parametric. The centrifugal and Coriolis impacts due to the spinning are taken into account. The stresses and strains would be obtained using the first-order-shear-deformable-theory (FSDT). For Poisson ratio, as well as various amounts of mass densities, the mixture rule is employed, while a modified Halpin-Tsai model is inserted for achieving the elasticity module. The structure's boundary conditions (BCs) are obtained employing GPLs reinforced composite (GPLRC) spinning disk's governing equations applying principle of Hamilton which is based on minimum energy and ultimately have been solved employing numerical approach called generalized-differential quadrature-method (GDQM). Spinning disk's dynamic properties with different boundary conditions (BCs) are explained due to the curves drawn by Matlab software. Also, the simply-supported boundary conditions is applied to edges 𝜃=𝜋/2, and 𝜃=3𝜋/2, while, cantilever, respectively, is analyzed in R=R_i, and R₀. The final results reveal that the GPLs' weight fraction, viscoelastic substrate, various GPLs' pattern, and rotational velocity have a dramatic influence on the amplitude, and vibration behavior of a GPLRC rotating cantilevered disk. As an applicable result in related industries, the spinning velocity impact on the frequency is more effective in the higher radius ratio's amounts.

• The Journal of Industrial Distribution & Business
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• v.13 no.7
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• pp.7-16
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• 2022

Purpose: The therapeutic process has various benefits since it relives most of the stresses that people are undergoing in their various working places. Thus this study will determine this process's impact on workers in their different working places. Most of the workers that are being affected by stress and use this technique are the nurses. Research design, data and methodology: The present research conducted the PRISMA process which are important in research as it provides information that individual studies cannot. Guided by a specific research question, systematic reviews collate empirical evidence that fits particular criteria to provide a summary of available evidence. Results: The findings of all fifteen investigations were reviewed, but those with the strongest evidence were given more weight. Observers should be aware that the findings on aromatherapy approaches for nurses and patients are so uniform that advice might apply to both in a high acuity workplace. Conclusions: This research concludes that with the exception of a few rare exceptions, aromatherapy is a very efficient and safe treatment that does not build up in the body, but instead is expelled via the lungs, liver and kidneys. Non-invasive aromatherapy immediately affects the brain, and anyone may give the treatment at any time or place, regardless of the location.

• Structural Engineering and Mechanics
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• v.83 no.2
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• pp.179-193
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• 2022

The shear behaviour of reinforced concrete members has been studied over the past decades by various researchers, and it can be simulated by analysing shear panel elements which has been regarded as a basic element of reinforced concrete members subjected to in-plane biaxial stresses. Despite various experimental studies on shear panel element which have been conducted so far, there are still a lot of uncertainties related to what influencing factors govern the shear behaviour and affect failure mechanism in reinforced concrete members. To identify the uncertainties, a finite element analysis can be used, which enables to investigate the impact of specific variables such as the reinforcement ratio, the shear retention factor, and the material characteristics including aggregate interlock, tension stiffening, compressive softening, and shear behaviour at the crack surface. In this study, a non-linear probabilistic analysis was conducted on reinforced concrete panels using a finite element method optimized for reinforced concrete members and advanced sampling techniques so that probabilistic analysis can be performed effectively. Consequently, this study figures out what analysis methodology and input parameters have the most influence on shear behaviour of reinforced concrete panels.

• Advances in nano research
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• v.12 no.2
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• pp.117-137
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• 2022

Effect of thickness stretching on free vibration, bending and buckling behavior of carbon nanotubes reinforced composite (CNTRC) laminated nanoplates rested on new variable elastic foundation is investigated in this paper using a developed four-unknown quasi-3D higher-order shear deformation theory (HSDT). The key feature of this theoretical formulation is that, in addition to considering the thickness stretching effect, the number of unknowns of the displacement field is reduced to four, and which is more than five in the other models. Two new forms of CNTs reinforcement distribution are proposed and analyzed based on cosine functions. By considering the higher-order nonlocal strain gradient theory, microstructure and length scale influences are included. Variational method is developed to derive the governing equation and Galerkin method is employed to derive an analytical solution of governing equilibrium equations. Two-dimensional variable Winkler elastic foundation is suggested in this study for the first time. A parametric study is executed to determine the impact of the reinforcement patterns, nonlocal parameter, length scale parameter, side-t-thickness ratio and aspect ratio, elastic foundation and various boundary conditions on bending, buckling and free vibration responses of the CNTRC plate.

• Structural Engineering and Mechanics
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• v.84 no.6
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• pp.783-798
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• 2022

This study attempts to investigate the impact of thickness stretching and nonlinear hygro-thermo-mechanical loading on the bending behavior of FG beams. Young's modulus, thermal expansion, and moisture concentration coefficients vary gradually and continuously according to a power-law distribution in terms of the volume fractions of the constituent materials. In addition, the interaction between the thermal, mechanical, and moisture loads is involved in the governing equilibrium equations. Using the present developed analytical model and Navier's solution technique, the numerical results of non-dimensional stresses and displacements are compared with those obtained by other 3D theories. Furthermore, the present analytical model is appropriate for investigating the static bending of FG beams exposed to intense hygro-thermo-mechanical loading used for special technical applications in aerospace, automobile, and civil engineering constructions.