Search results for: mode II critical stress intensity factor

Authors: Ahlem Bahi, Youcef Necib, Sakina Zerizer, Cherif Abdennour, Mohamed Salah Boulakoud

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Mercury (II) is a highly toxic metal which induces oxidative stress in the body. In this study, we aimed to investigate the possible protective effect of olive oil, an antioxidant agent, against experimental mercury toxicity in rat model. Administration of mercuric chloride induced significant increase in serum: ALT, AST, and LPA activities; interleukine1, interleukine6, tumor necrosis factor α (TNFα), creatinine, urea, and uric acid levels. Mercuric chloride also induced oxidative stress, as indicate by decreased tissue of GSH level, GSH-Px, and GST activities along with increase the level of lipid peroxidation. Furthermore, treatment with mercuric chloride caused a marked elevation of kidney and liver weight and decreased body weight. Virgin olive oil treatment markedly reduced elevated serum: AST, ALT, and LPA activities; interleukine1, interleukine6, tumor necrosis factor α (TNFα), creatinine, urea, and uric acid levels and contracted the deterious effects of mercuric chloride on oxidative stress markers changes caused by HgCl2 in tissue as compared to control group. Our results implicate that mercury induced oxidative damage in liver and kidney tissue protected by virgin olive oil, with its antioxidant effects.

Keywords: mercury, antioxidant enzymes, pro-inflammatory cytokine, virgin olive oil, lipid peroxidation

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Authors: Anurag Niranjan, Michael Fitzpatrick, Yin Jin Janin, Jazeel Chukkan, Niall Smyth

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Fillet welds are used in joining longitudinal stiffeners in ship structures. Welding residual stresses in fillet welds are generally distributed in a non-uniform manner, as shown in previous research the residual stress redistribution occurs under the cyclic loading that is experienced by such joints during service, and the combination of the initial residual stress, local constraints, and loading can alter the stress field in ways that are extremely difficult to predict. As the residual stress influences the crack propagation originating from the toe of the fillet welds, full understanding of the residual stress field and how it evolves is very important for structural integrity calculations. Knowledge of the residual stress redistribution in the presence of a flaw is therefore required for better fatigue life prediction. Moreover, defect assessment procedures such as BS7910 offer very limited guidance for flaw acceptance and the associated residual stress redistribution in the assessment of fillet welds. Therefore the objective of this work is to study a surface-breaking flaw at the weld toe region in a fillet weld under cyclic load, in conjunction with residual stress measurement at pre-defined crack depths. This work will provide details of residual stress redistribution under cyclic load in the presence of a crack. The outcome of this project will inform integrity assessment with respect to the treatment of residual stress in fillet welds. Knowledge of the residual stress evolution for this weld geometry will be greatly beneficial for flaw tolerance assessments (BS 7910, API 591).

Keywords: fillet weld, fatigue, residual stress, structure integrity

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Authors: Terri A. Croteau, Todd G. Morrison

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Despite increased scholarly attention paid to minority stress and sexual satisfaction among sexual minorities, to the authors’ knowledge, no researchers, to date, have attempted to synthesize this literature. To address this omission, the authors conducted a meta-analytic review of the association between sexual minority stress (i.e., sexual identity stigma, internalized sexual identity stigma, and sexual identity concealment) and sexual satisfaction. Twenty-seven articles containing 58 effect sizes were analyzed (N = 183,582). Findings indicated a small, inverse relationship between these constructs, indicating that minority stress may lead to diminished sexual satisfaction among gay/lesbian and bisexual individuals. Further, the overall effect size varied as a function of minority stress type, such that the effect for internalized stigma was significantly larger than the effects for stigma or concealment. Age also moderated the relationship between minority stress and sexual satisfaction; specifically, older age was associated with a smaller effect, suggesting that older adults may be better at coping with minority stress than younger adults. Limitations, implications, and directions for future research are discussed.

Keywords: minority stress, stigma, sexual satisfaction, sexual minorities

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Authors: Martin Alexander Eder, Sergei Semenov

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Many glass-epoxy composite structures, such as large utility wind turbine rotor blades (WTBs), comprise of adhesive joints with typically thick bond lines used to connect the different components during assembly. Performance optimization of rotor blades to increase power output by simultaneously maintaining high stiffness-to-low-mass ratios entails intricate geometries in conjunction with complex anisotropic material behavior. Consequently, adhesive joints in WTBs are subject to multiaxial stress states with significant stress gradients depending on the local joint geometry. Moreover, the dynamic aero-elastic interaction of the WTB with the airflow generates non-proportional, variable amplitude stress histories in the material. Empiricism shows that a prominent failure type in WTBs is high cycle fatigue failure of adhesive bond line interfaces, which in fact over time developed into a design driver as WTB sizes increase rapidly. Structural optimization employed at an early design stage, therefore, sets high demands on computationally efficient interface fatigue models capable of predicting the critical locations prone for interface failure. The numerical stress-based interface fatigue model presented in this work uses the Drucker-Prager criterion to compute three different damage indices corresponding to the two interface shear tractions and the outward normal traction. The two-parameter Drucker-Prager model was chosen because of its ability to consider shear strength enhancement under compression and shear strength reduction under tension. The governing interface damage index is taken as the maximum of the triple. The damage indices are computed through the well-known linear Palmgren-Miner rule after separate rain flow-counting of the equivalent shear stress history and the equivalent pure normal stress history. The equivalent stress signals are obtained by self-similar scaling of the Drucker-Prager surface whose shape is defined by the uniaxial tensile strength and the shear strength such that it intersects with the stress point at every time step. This approach implicitly assumes that the damage caused by the prevailing multiaxial stress state is the same as the damage caused by an amplified equivalent uniaxial stress state in the three interface directions. The model was implemented as Python plug-in for the commercially available finite element code Abaqus for its use with solid elements. The model was used to predict the interface damage of an adhesively bonded, tapered glass-epoxy composite cantilever I-beam tested by LM Wind Power under constant amplitude compression-compression tip load in the high cycle fatigue regime. Results show that the model was able to predict the location of debonding in the adhesive interface between the webfoot and the cap. Moreover, with a set of two different constant life diagrams namely in shear and tension, it was possible to predict both the fatigue lifetime and the failure mode of the sub-component with reasonable accuracy. It can be concluded that the fidelity, robustness and computational efficiency of the proposed model make it especially suitable for rapid fatigue damage screening of large 3D finite element models subject to complex dynamic load histories.

Keywords: adhesive, fatigue, interface, multiaxial stress

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Authors: Wieslaw Marszalek, Zdzislaw Trzaska

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Interesting properties of various one-period loops of singularly perturbed memristive circuits with mixed-mode oscillations (MMOs) are analyzed in this paper. The analysis is mixed, both analytical and numerical and focused on the properties of pinched hysteresis of the memristive element and other one-period loops formed by pairs of time-series solutions for various circuits' variables. The memristive element is the only nonlinear element in the two circuits. A theorem on periods of mixed-mode oscillations of the circuits is formulated and proved. Replacements of memristors by parallel G-C or series R-L circuits for a MMO response with equivalent RMS values is also discussed.

Keywords: mixed-mode oscillations, memristive circuits, pinched hysteresis, one-period loops, singularly perturbed circuits

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Authors: M. A. Peribanez, G. Illan, I. De Blas, A. Muniesa, I. Ruiz-Zarzuela

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Intensive aquaculture is commonly associated with increased incidence of parasites. However, in Spain, the recent intensification of cyprinid production has not led to knowledge of the parasites that develop in the aquaculture facilities, the factors that affect their development and spread and the transmission between wild and cultivated fish species. The present study focuses on the knowledge of environmental factors, as well as host dependent factors, and their possible influence as risk factors in the incidence and intensity of parasitic infections. This work was conducted in the Duero River Basin, NW Spain. A total of 114 tenches (Tinca tinca) were caught in a fish farm and 667 specimens belonging to six species of cyprinid, not tench, in five rivers. An exhaustive search and microscopic identification of protozoa on skin and gills were carried out. Physical, chemical, and biological parameters of water samples from the capture points were determined. Only two ectoprotozoa were identified, Ichthyophthirius multifiliis and Tripartiella sp. In I. multifiliis, a high intensity of infection (more than 40 parasites on the body surface and more than 80 on gills) was determined in farmed tench (14%) and in Iberian barbel (Luciobarbus bocagei) (91%) and Duero nase (Pseudochondrostoma duriense) (71%) of middle stretches of rivers. The prevalence was similar between farmed tenches and cyprinids of middle courses. Tripartiella sp. was only found in barbels (prevalence in middle stretches, 0.7%) and in farmed tenches (63%), this species resulting in a high risk factor (odds ratio, OR= 1143) in the presence of the ciliate. There were no differences between the two species relative to the intensity of parasitization. Some of the physical, chemical and microbiological water quality parameters appear to be risk factors in the presence of I. multifiliis, with maximum OR of 8. Nevertheless, in Tripartiella sp., the risk is multiplied by 720 when the pH value exceeds 8.4, if we consider the total of the data, and it is increased more than 500 times if we only consider the values recorded in the fish farm (529 by nitrates > 3 mg/l; 530 by total coliforms > 100 CFU/100 ml). However, the high prevalence and risk of infection by I. multifiliis and Tripartiella sp. in fish farms should be related to environmental factors that dependent upon sampling point rather than in direct influence of the physical-chemical and biological parameters of the water. The high pH value recorded in the fish farm (9.62 ± 0.76) is the only parameter that we consider may have a substantial direct influence. Chronic exposure to alkaline pH levels can be a chronic stress generator, predisposing to parasitization by Tripartiella sp. In conclusion, often minor changes in ecosystem conditions, both natural and man-made, can modify the host-parasite relationship, resulting in an increase in the prevalence and intensity of parasitic infections in populations of cyprinids, sometimes causing disease outbreaks.

Keywords: cyprinids, fish, parasites, protozoa, risk factors

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Authors: Wei Jun, Liao Hualin, Wang Huajian, Chen Jingkai, Liang Hongjun, Liu Chuanfu

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Kuqa Piedmont is rich in oil and gas resources and has great development potential in Tarim Basin, China. However, there is a huge thick gravel layer developed with high content, wide distribution and variation in size of gravel, leading to the condition of strong heterogeneity. So that, the drill string is in a state of severe vibration and the drill bit is worn seriously while drilling, which greatly reduces the rock-breaking efficiency, and there is a complex load state of impact and three-dimensional in-situ stress acting on the rock in the bottom hole. The dynamic mechanical properties and the influencing factors of conglomerate, the main component of gravel layer, are the basis of engineering design and efficient rock breaking method and theoretical research. Limited by the previously experimental technique, there are few works published yet about conglomerate, especially rare in dynamic load. Based on this, a kind of 3D SHPB system, three-dimensional prestress, can be applied to simulate the in-situ stress characteristics, is adopted for the dynamic test of the conglomerate. The results show that the dynamic strength is higher than its static strength obviously, and while the three-dimensional prestress is 0 and the loading strain rate is 81.25~228.42 s-1, the true triaxial equivalent strength is 167.17~199.87 MPa, and the strong growth factor of dynamic and static is 1.61~1.92. And the higher the impact velocity, the greater the loading strain rate, the higher the dynamic strength and the greater the failure strain, which all increase linearly. There is a critical prestress in the impact direction and its vertical direction. In the impact direction, while the prestress is less than the critical one, the dynamic strength and the loading strain rate increase linearly; otherwise, the strength decreases slightly and the strain rate decreases rapidly. In the vertical direction of impact load, the strength increases and the strain rate decreases linearly before the critical prestress, after that, oppositely. The dynamic strength of the conglomerate can be reduced properly by reducing the amplitude of impact load so that the service life of rock-breaking tools can be prolonged while drilling in the stratum rich in gravel. The research has important reference significance for the speed-increasing technology and theoretical research while drilling in gravel layer.

Keywords: huge thick gravel layer, conglomerate, 3D SHPB, dynamic strength, the deformation characteristics, prestress

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Authors: V. Tabrizi, A. Vali, R. GHasemi, V. Behnamgol

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In this article, a nonlinear model of an under actuated six degrees of freedom (6 DOF) quadrotor UAV is derived on the basis of the Newton-Euler formula. The derivation comprises determining equations of the motion of the quadrotor in three dimensions and approximating the actuation forces through the modeling of aerodynamic coefficients and electric motor dynamics. The robust nonlinear control strategy includes a smooth second order non-singular terminal sliding mode control which is applied to stabilizing this model. The control method is on the basis of super twisting algorithm for removing the chattering and producing smooth control signal. Also, nonsingular terminal sliding mode idea is used for introducing a nonlinear sliding variable that guarantees the finite time convergence in sliding phase. Simulation results show that the proposed algorithm is robust against uncertainty or disturbance and guarantees a fast and precise control signal.

Keywords: quadrotor UAV, nonsingular terminal sliding mode, second order sliding mode t, electronics, control, signal processing

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Authors: Feri̇t Çakici, M. Kemal Leblebi̇ci̇oğlu

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In this study, an unmanned aerial vehicle (UAV) with level flight, vertical take-off and landing (VTOL) and mode-transitioning capability is designed and analyzed. The platform design combines both multirotor and fixed-wing (FW) conventional airplane structures and control surfaces; therefore named as VTOL-FW. The aircraft is modeled using aerodynamical principles and linear models are constructed utilizing small perturbation theory for trim conditions. The proposed method of control includes implementation of multirotor and airplane mode controllers and design of an algorithm to transition between modes in achieving smooth switching maneuvers between VTOL and FW flight. Thus, VTOL-FW UAV’s flight characteristics are expected to be improved by enlarging operational flight envelope through enabling mode-transitioning, agile maneuvers and increasing survivability. Experiments conducted in simulation and real world environments shows that VTOL-FW UAV has both multirotor and airplane characteristics with extra benefits in an enlarged flight envelope.

Keywords: aircraft design, linear analysis, mode transitioning control, UAV

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Authors: Aisha Bano, Rizwan Nazir

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The present study aimed at exploring the impact of meaning in life on psychological well-being and stress among university students. Victor Frankl's paradigm provided the theoretical foundation for this study. A sample of 560 university students was drawn from Quaid-i-Azam University Islamabad. The sample was drawn using stratified random sampling technique. Data were collected using Existence Scale, Warwick-Edinburg Mental Well-Being Scale, and Stress Scale. Results of linear regression analysis reveals that high perception of meaning in life will lead to high psychological well-being and low stress among university students. Non-significant differences are found on meaning in life variable with regard to gender in the sample using t-test. Together these results suggest that meaning in life independent of gender, is a significant predictor of the levels of stress and psychological well-being being directly related to psychological well-being and inversely related to stress levels.

Keywords: existential meaning in life, psychological well-being, stress, students

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Authors: Sanjeet Patra, Soham Roychowdhury

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In recent times, functionally graded dielectric elastomer (FGDE) has gained significant attention within the realm of soft actuation due to its dual capacity to exert highly localized stresses while maintaining its compliant characteristics on application of electro-mechanical loading. Nevertheless, the full potential of dielectric elastomer (DE) has not been fully explored due to their susceptibility to instabilities when subjected to electro-mechanical loads. As a result, study and analysis of such instabilities becomes crucial for the design and realization of dielectric actuators. Prismatic bifurcation is a type of instability that has been recognized in a DE tube. Though several studies have reported on the analysis for prismatic bifurcation in an isotropic DE tube, there is an insufficiency in studies related to prismatic bifurcation of FGDE tubes. Therefore, this paper aims to determine the onset of prismatic bifurcations on an incompressible FGDE tube when subjected to electrical loading across the thickness of the tube and internal pressurization. The analysis has been conducted by imposing two axial boundary conditions on the tube, specifically axially free ends and axially clamped ends. Additionally, the rigidity modulus of the tube has been linearly graded in the direction of thickness where the inner surface of the tube has a lower stiffness than the outer surface. The static equilibrium equations for deformation of the axisymmetric tube are derived and solved using numerical technique. The condition for prismatic bifurcation of the axisymmetric static equilibrium solutions has been obtained by using the linearized incremental constitutive equations. Two modes of bifurcations, corresponding to two different non-circular cross-sectional geometries, have been explored in this study. The outcomes reveal that the FGDE tubes experiences prismatic bifurcation before the Hessian criterion of failure is satisfied. It is observed that the lower mode of bifurcation can be triggered at a lower critical voltage as compared to the higher mode of bifurcation. Furthermore, the tubes with larger stiffness gradient require higher critical voltages for triggering the bifurcation. Moreover, with the increase in stiffness gradient, a linear variation of the critical voltage is observed with the thickness of the tube. It has been found that on applying internal pressure to a tube with low thickness, the tube becomes less susceptible to bifurcations. A thicker tube with axially free end is found to be more stable than the axially clamped end tube at higher mode of bifurcation.

Keywords: critical voltage, functionally graded dielectric elastomer, linearized incremental approach, modulus of rigidity, prismatic bifurcation

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Authors: Bin Shi, Mouhab Meshreki, Grégoire Bazin, Helmi Attia

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Large monolithic components are widely used in the aerospace industry in order to reduce airplane weight. Milling is an important operation in manufacturing of the monolithic parts. More than 90% of the material could be removed in the milling operation to obtain the final shape. This results in low rigidity and post-machining distortion. The post-machining distortion is the deviation of the final shape from the original design after releasing the clamps. It is a major challenge in machining of the monolithic parts, which costs billions of economic losses every year. Three sources are directly related to the part distortion, including initial residual stresses (RS) generated from previous manufacturing processes, machining-induced RS and thermal load generated during machining. A finite element model was developed to simulate a milling process and predicate the post-machining distortion. In this study, a rolled-aluminum plate AA7175 with a thickness of 60 mm was used for the raw block. The initial residual stress distribution in the block was measured using a layer-removal method. A stress-mapping technique was developed to implement the initial stress distribution into the part. It is demonstrated that this technique significantly accelerates the simulation time. Machining-induced residual stresses on the machined surface were measured using MTS3000 hole-drilling strain-gauge system. The measured RS was applied on the machined surface of a plate to predict the distortion. The predicted distortion was compared with experimental results. It is found that the effect of the machining-induced residual stress on the distortion of a thick plate is very limited. The distortion can be ignored if the wall thickness is larger than a certain value. The RS generated from the thermal load during machining is another important factor causing part distortion. Very limited number of research on this topic was reported in literature. A coupled thermo-mechanical FE model was developed to evaluate the thermal effect on the plastic deformation of a plate. A moving heat source with a feed rate was used to simulate the dynamic cutting heat in a milling process. When the heat source passed the part surface, a small layer was removed to simulate the cutting operation. The results show that for different feed rates and plate thicknesses, the plastic deformation/distortion occurs only if the temperature exceeds a critical level. It was found that the initial residual stress has a major contribution to the part distortion. The machining-induced stress has limited influence on the distortion for thin-wall structure when the wall thickness is larger than a certain value. The thermal load can also generate part distortion when the cutting temperature is above a critical level. The developed numerical model was employed to predict the distortion of a frame part with complex structures. The predictions were compared with the experimental measurements, showing both are in good agreement. Through optimization of the position of the part inside the raw plate using the developed numerical models, the part distortion can be significantly reduced by 50%.

Keywords: modelling, monolithic parts, optimization, post-machining distortion, residual stresses

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Authors: Philip Rose, Markus Linke, David Busquets

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The distinction between interlaminar and intralaminar fracture toughness has already been investigated by several authors. For loading mode I, the double cantilever beam specimens were often used for the interlaminar fracture toughness and the compact tension specimen for the intralaminar fracture toughness. In order to minimize the influence of the different specimen geometries, a method was developed which allows the determination of both the interlaminar and the intralaminar fracture toughness on an almost identical specimen geometry. However, as this method is not applicable to prepreg semi-finished products, a further modification was developed, which is also suitable for prepreg laminates. After the successful application for the investigation of mode I with this method, the application of the method for loading mode II is presented in this paper. In addition to manufacturing differences, due to an additional fiber ply in which the controlled crack growth takes place, the adapted test procedure is also explained. By comparing the test results of standardized end-notched flexure (ENF) specimens with those of the modified ENF specimen, the difference between the interlaminar and intralaminar fracture toughness of the material Hexply 8552/IM7 is shown.

Keywords: ENF, fracture toughness, interlaminar, mode II

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Authors: M. Khazam, M. Altawil, A. Eljabri

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Fluid properties in states near a vapor-liquid critical region are the most difficult to measure and to predict with EoS models. The principal model difficulty is that near-critical property variations do not follow the same mathematics as at conditions far away from the critical region. Libyan NC98 field in Sirte basin is a typical example of near critical fluid characterized by high initial condensate gas ratio (CGR) greater than 160 bbl/MMscf and maximum liquid drop-out of 25%. The objective of this paper is to model NC98 phase behavior with the proper selection of EoS parameters and also to model reservoir depletion versus gas cycling option using measured PVT data and EoS Models. The outcomes of our study revealed that, for accurate gas and condensate recovery forecast during depletion, the most important PVT data to match are the gas phase Z-factor and C7+ fraction as functions of pressure. Reasonable match, within -3% error, was achieved for ultimate condensate recovery at abandonment pressure of 1500 psia. The smooth transition from gas-condensate to volatile oil was fairly simulated by the tuned PR-EoS. The predicted GOC was approximately at 14,380 ftss. The optimum gas cycling scheme, in order to maximize condensate recovery, should not be performed at pressures less than 5700 psia. The contribution of condensate vaporization for such field is marginal, within 8% to 14%, compared to gas-gas miscible displacement. Therefore, it is always recommended, if gas recycle scheme to be considered for this field, to start it at the early stage of field development.

Keywords: EoS models, gas-condensate, gas cycling, near critical fluid

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Authors: H. Gholami, M. Jalali Azizpour

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For materials such as hard coating whose stresses state are difficult to obtain by a widely used method called high-speed hole-drilling method (ASTM Standard E837). It is important to develop a non contact method. This process itself imposes an additional stresses. The through thickness residual stress of st37 steel using elector-discharge was investigated. The strain gage and dynamic strain indicator used in all cases was FRS-2-11 rosette type and TML 221, respectively. The average residual stress in depth of 320 µm was -6.47 MPa.

Keywords: HVOF, residual stress, thermal spray, WC-Co

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Authors: Mike Seal

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This paper explores the traditions of critical and queer pedagogy, its intersections, tensions and paradoxes. Critical pedagogy, with a materialist realist ontology, and queer theory, which is often post-modern, post-structural and anti-essential, may not seem compatible. Similarly, there are tensions between activist orientations, often enacted through essential sexual identities, and a queer approach that questions such identities and subjectivities. It will argue that critical realism gives us a bridge between critical and queer pedagogy in preserving a realist materialist ontology, where economic forces are real, and independent of consciousness and hermeneutic constructions of them. At the same time, it offers an epistemology that does not necessitate a binary view of the roles of the oppressed, liberator, or even oppressor. It accepts that our knowledge is contingent, partial and contestable, but has the potential, and enough validity, to demand action and potentially inform the actions of others.

Keywords: critical pedagogy, queer pedagogy, critical realsim, heteronormativity

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Authors: Kamel Hachour, Lydia Sadeg, Djamel Sersab, Tassadit Bellahcen

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The hydrostatic stress is, for polymers, a significant parameter which affects the yield behavior of these materials. In this work, we investigate the influence of this parameter on yield behavior of the high density polyethylene (hdpe). Some tests on specimens with diverse geometries are described in this paper. Uniaxial tests: tensile on notched round bar specimens with different curvature radii, compression on cylindrical specimens and simple shear on parallelepiped specimens were performed. Biaxial tests with various combinations of tensile/compressive and shear loading on butterfly specimens were also realized in order to determine the hydrostatic stress for different states of solicitation. The experimental results show that the yield stress is very affected by the hydrostatic stress developed in the material during solicitations.

Keywords: biaxial tests, hdpe, Hydrostatic stress, yield behavior

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Authors: Masoud Rafiee

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To study the quality response of forage to chickpea-barley mixed cropping under drought stress and vermicompost consumption, an experiment was carried out under well watered and %70 water requirement (stress condition) in RCBD as split plot with four replications in temperate condition of Khorramabad in 2013. Chickpea-barley mix cropping (%100 chickpea, %75:25 chickpea:barley, %50:50 chickpea:barley, %25:75 chickpea:barley, and %100 barley) was studied. Results showed that wet and dry forage yield were significantly affected by environment and decreased in stress condition. Also, crude protein content decreased from %26.2 in well watered to %17.3 in stress condition.

Keywords: crude protein, wet forage yield, dry forage yield, water stress condition, well watered

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Authors: Hevriani Sevrika Mayuasti

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This research deals in improving college students’ critical thinking at English for Specific Purposes Subject. The strategy that is applied is Bloom’s Critical Thinking Questioning Strategy. The positive side of this strategy is that the given questions are developed based on Bloom’s taxonomy level. It is an action research because the researcher uses own class in doing this research. The processes of this research have been done from April to Mei 2014. There are two cycles and each cycle consists of two meetings. After doing the research, it is gotten that Bloom’s Critical Thinking Questioning Strategy improves college students’ critical thinking. It helps the students to build and elaborate their ideas. Hence, it increases students’ reading comprehension.

Keywords: critical thinking, blooms’ critical thinking, questioning, strategy

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Authors: Melissa Dorsey

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Moral distress and compassion fatigue plague nurses in the Cardiothoracic Intensive Care Unit (CTICU) and cause an unnecessary level of turnover. Dueling Burnout describes an initiative that was implemented in the CTICU to reduce the level of burnout the nurses endure by encouraging dual roles with collaborating departments. Purpose: Critical care nurses are plagued by burnout, moral distress, and compassion fatigue due to the intensity of care provided. The purpose of the dual role program was to decrease these issues by providing relief from the intensity of the critical care environment while maintaining full-time employment. Relevance/Significance: Burnout, moral distress, and compassion fatigue are leading causes of Cardiothoracic Critical Care (CTCU) turnover. A contributing factor to burnout is the workload related to serving as a preceptor for a constant influx of new nurses (RN). As a result of these factors, the CTICU averages 17% nursing turnover/year. The cost, unit disruption, and, most importantly, distress of the clinical nurses required an innovative approach to create an improved work environment and experience. Strategies/Implementation/Methods: In May 2018, a dual role pilot was initiated for nurses. The dual role constitutes .6 full-time equivalent hours (FTE) worked in CTICU in combination with .3 FTE worked in the Emergency Department (ED). ED nurses who expressed an interest in cross-training to CTICU were also offered the dual role opportunity. The initial hypothesis was that full-time employees would benefit from a change in clinical setting leading to increased engagement and job satisfaction. The dual role also presents an opportunity for professional development through the expansion of clinical skills in another specialty. Success of the pilot led to extending the dual role to areas beyond the ED. Evaluation/Outcomes/Results: The number of dual role clinical nurses has grown to 22. From the dual role cohort, only one has transferred out of CTICU. This is a 5% turnover rate for this group of nurses as compared to the average turnover rate of 17%. A role satisfaction survey conducted with the dual role cohort found that because of working in a dual role, 76.5% decreased their intent to leave, 100% decreased their level of burnout, and 100% reported an increase in overall job satisfaction. Nurses reported the ability to develop skills that are transferable between departments. Respondents emphasized the appreciation gained from working in multiple environments; the dual role served to transform their care. Conclusions/Implications: Dual role is an effective strategy to retain experienced nurses, decrease burnout and turnover, improve collaboration, and provide flexibility to meet staffing needs. The dual role offers RNs an expansion of skills, relief from high acuity and orientee demands, while improving job satisfaction.

Keywords: nursing retention, burnout, pandemic, strategic staffing, leadership

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Authors: Solomon Huluka, Akrum Abdul-Latif, Rachid Baleh

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Metal foams have been developed intensively as a new class of materials for the last two decades due to their unique structural and multifunctional properties. The aim of this experimental work was to characterize the effect of biaxial loading complexity (combined compression-torsion) on the plastic response of highly uniform architecture open-cell aluminum foams of spherical porous with a density of 80%. For foam manufacturing, the Kelvin cells model was used to generate the generally spherical shape with a cell diameter of 11 mm. A patented rig called ACTP (Absorption par Compression-Torsion Plastique), was used to investigate the foam response under quasi-static complex loading paths having different torsional components (i.e. 0°, 45° and 60°). The key mechanical responses to be examined are yield stress, stress plateau, and energy absorption capacity. The collapse mode was also investigated. It was concluded that the higher the loading complexity, the greater the yield strength and the greater energy absorption capacity of the foam. Experimentally, it was also noticed that there were large softening effects that occurred after the first pick stress for both biaxial-45° and biaxial-60° loading.

Keywords: aluminum foam, loading complexity, characterization, biaxial loading

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Authors: Saeed Rauf

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Purpose: Drought stress is a major production constraint in sunflowers and causes yield losses under tropical and subtropical environments having high evapo-tranpirational losses. Given the consequences, three trials were designed to evaluate drought-resistant sunflower hybrids. Research Methods: Field trials were conducted under a split-plot arrangement with 17 hybrids and two contrasting regimes at Sargodha, Pakistan and 7 hybrids at Karj, Iran. Water stress condition was simulated by holding water in a stress regime. Hybrids were also screened against five levels of osmotic-ally induced stress, i.e. 0-15%, under a completely randomized design with 3 replications. Findings: Hybrids H1 (C.112.× RH.344) and H3 (C.112.× RSIN.82) showed the highest seed yield ha-1 and early flowering at Karj Iran. Commercial hybrid had the highest CTD (18.2°C) followed by C112 × RH.344 (17.29 °C). Hybrid C.250 × R.SIN.82 had the highest seed yield (m-2), followed by C.112 × RH.365 and C.124 × RSIN.82 under both stress and non-stress regimes at Sargodha, Pakistan. Seedling trial results showed that 6 hybrids only germinated in 5 and 7.5% PEG-induced osmotic stress, respectively. H1 (C.112 × RH.344) and H2 (C.112 × RH.347) had the highest germination% at 5% and 7.5% osmotic stress (OS). Seedling vigor index (SVI) was the highest in H1 (C.112 × RH.344) hybrids at 5% OS, H2 had the highest SVI under 7.5% OS, followed by H3 (C112 × RH344) and H4 (C116 × RH344). Originality/Value: In view of above results, it was concluded that hybrid combination H1 had the highest seed yield under stress conditions in both environments. High seed yield may be due to its better germination and vigor index under stress conditions.

Keywords: climate change, CTD, genetic variability, osmotic stress

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Authors: Zulfajri Basri Hasanuddin

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There is an increasing demand for broadband services in Indonesia. Therefore, the answer is the use of Ka-Band which has some advantages such as wider bandwidth, the higher transmission speeds, and smaller size of antenna in the ground. However, rain attenuation is the primary factor in the degradation of signal at the Kaband. In this paper, the author will determine whether the Ka-band frequency can be implemented in Indonesia which has high intensity of rainfall.

Keywords: Ka-band, link budget, link availability, BER, Eb/No, C/N

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Authors: Neha Bharti, Martin Sénéchal, Danielle R. Bouchard

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Mostly attributed to lack of time, only 15% of adults currently reach the International Physical Activity Guidelines, which state that every adult should achieve minimum of 150 minutes of aerobic exercise per week at moderate to vigorous intensity in minimum bouts of 10 minutes each, in addition to two days of resistance training. Recent studies have suggested that any bout of aerobic exercise reaching moderate intensity has potential to improve health. If one could reach moderate intensity while doing resistance training, this could reduce the total weekly time involvement to reach the International Physical Activity Guidelines. Objectives: 1) To determine whether overweight and older adults can reach a minimum of moderate intensity while doing resistance training compared with young non-overweight adults, 2) To identify if the proportion of time spent at moderate to vigorous intensity is different in overweight adults and older adults when compared with young non-overweight adults when lifting 70% or 80% of maximal load, 3) To determine variables associated with proportion of time spent at moderate to vigorous intensity while doing resistance training. Methods: Sixty participants already doing resistance training were recruited (20 young non-overweight adults, 20 overweight adults, and 20 older adults). Participants visited fitness facility three times, separated by at least 48 hours, and performed eight resistance exercises each time. First visit was to collect baseline measurements and to measure maximal load for each of the eight exercises. Second and third visits were performed wearing a heart rate monitor to record heart rate and to measure exercise intensity. The two exercise sessions were performed at 70% and 80% of maximal capacity. Moderate intensity was defined as 40% of heart rate reserve. Results: The proportion of time spent at moderate to vigorous intensity ranged from 51% to 93% among the three groups. No difference was observed between the young group and the overweight adults group in the proportion of time spent at moderate to vigorous intensity, 82.6% (69.2-94.6) vs 92.5% (73.3-99.1). However, older adults spent lower proportion of time at moderate to vigorous intensity for both sessions 51.5% (22.0-86.6); P < .01. When doing resistance training at 70% and 80% of maximal capacity, the proportion of time spent at moderate to vigorous intensity was 82.3% (56.1-94.7) and 82.0% (59.2-98.0) with no significant difference (P=.83). Conclusion: This study suggests that overweight adults and older adults can reach moderate intensity for at least 51% of the time spent doing resistance training. However, time spent at moderate to vigorous intensity was lower for older adults compared to young non-overweight adults. For adults aged 60 or less, three resistance training sessions of 60 minutes weekly could be enough to reach both aerobic and resistance training components of the International Physical Activity Guidelines. Further research is needed to test if resistance training at moderate to vigorous intensity can have the same health benefits compared with adults completing the International Physical Activity Guidelines as currently suggested.

Keywords: aerobic exercise, international physical activity guidelines, moderate to vigorous intensity, resistance training

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Authors: Archana Soni, Arvind Mittal, Manmohan Kapshe

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Energy has been recognized as one of the key inputs for the economic growth and social development of a country. High economic growth naturally means a high level of energy consumption. However, in the present energy scenario where there is a wide gap between the energy generation and energy consumption, it is extremely difficult to match the demand with the supply. India being one of the largest and rapidly growing developing countries, there is an impending energy crisis which requires immediate measures to be adopted. In this situation, the concept of Energy Intensity comes under special focus to ensure energy security in an environmentally sustainable way. Energy Intensity is defined as the energy consumed per unit output in the context of industrial energy practices. It is a key determinant of the projections of future energy demands which assists in policy making. Energy Intensity is inversely related to energy efficiency; lesser the energy required to produce a unit of output or service, the greater is the energy efficiency. Energy Intensity of Indian manufacturing industries is among the highest in the world and stands for enormous energy consumption. Hence, reducing the Energy Intensity of Indian manufacturing industries is one of the best strategies to achieve a low level of energy consumption and conserve energy. This study attempts to analyse the factors which influence the Energy Intensity of Indian manufacturing firms and how they can be used to reduce the Energy Intensity. The paper considers six of the largest energy consuming manufacturing industries in India viz. Aluminium, Cement, Iron & Steel Industries, Textile Industries, Fertilizer and Paper industries and conducts a detailed Energy Intensity analysis using the data from PROWESS database of the Centre for Monitoring Indian Economy (CMIE). A total of twelve independent explanatory variables based on various factors such as raw material, labour, machinery, repair and maintenance, production technology, outsourcing, research and development, number of employees, wages paid, profit margin and capital invested have been taken into consideration for the analysis.

Keywords: energy intensity, explanatory variables, manufacturing industries, PROWESS database

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Authors: Hosein Falahaty, Hitoshi Gotoh, Abbas Khayyer

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Performance of a Hamiltonian based particle method in simulation of nonlinear structural dynamics is subjected to investigation in terms of stability and accuracy. The governing equation of motion is derived based on Hamilton's principle of least action, while the deformation gradient is obtained according to Weighted Least Square method. The hyper-elasticity models of Saint Venant-Kirchhoff and a compressible version similar to Mooney- Rivlin are engaged for the calculation of second Piola-Kirchhoff stress tensor, respectively. Stability along with accuracy of numerical model is verified by reproducing critical stress fields in static and dynamic responses. As the results, although performance of Hamiltonian based model is evaluated as being acceptable in dealing with intense extensional stress fields, however kinds of instabilities reveal in the case of violent collision which can be most likely attributed to zero energy singular modes.

Keywords: Hamilton's principle of least action, particle-based method, hyper-elasticity, analysis of stability

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Authors: Mojtaba Esmaeilzad Limoudehi, Ebrahim Amiri

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Water scarcity is now one of the leading challenges for human societies. In this regard, recognizing the relationship between soil, water, plant growth, and plant response to stress is very significant. In this paper, considering the importance of drought stress and the role of choosing suitable cultivars in resistance against drought, a split-plot experiment using early, intermediate, and late-maturing cultivars was carried out in Katul filed, Golestan province during two cultivation years of 2015 and 2016. The main factor was irrigation intervals at four levels, including 7 days, 14 days, 21 days, and 28 days. The subfactor was the subplot of six maize cultivars (two early maturing cultivars, two medium maturing cultivars, and two late-maturing cultivars). The results of variance analysis have revealed that irrigation interval and cultivars treatment have significant effects on the number of grain in each corn, number of rows in each corn, number of grain per row, the weight of 1000 grains, grain yield, and biomass yield. Although, the interaction of these two factors on the mentioned attributes was meaningful. The best grain yield was achieved at 7 days irrigation interval and late maturing maize cultivars treatment, which was equal to 12301 kg/ha.

Keywords: corn, growth period, optimization, stress

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Authors: Charlotte K. Lee, Henrique R. N. Aguiar, Ralph Smith, James Baldock, Sam Botchey

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Background: Femoral neck stress fractures (FNSF) are uncommon, making up 1 to 7.2% of stress fractures in healthy subjects. FNSFs are prevalent in young women, military recruits, endurance athletes, and individuals with energy deficiency syndrome or female athlete triad. Presentation is often non-specific and is often misdiagnosed following the initial examination. There is limited research addressing the return–to–activity time after FNSF. Previous studies have demonstrated prognostic time predictions based on various imaging techniques. Here, (1) OxSport clinic FNSF practice standards are retrospectively reviewed, (2) FNSF cohort demographics are examined, (3) Regression models were used to predict return–to–activity prognosis and consequently determine bone stress risk factors. Methods: Patients with a diagnosis of FNSF attending Oxsport clinic between 01/06/2020 and 01/01/2020 were selected from the Rheumatology Assessment Database Innovation in Oxford (RhADiOn) and OxSport Stress Fracture Database (n = 14). (1) Clinical practice was audited against five criteria based on local and National Institute for Health Care Excellence guidance, with a 100% standard. (2) Demographics of the FNSF cohort were examined with Student’s T-Test. (3) Lastly, linear regression and Random Forest regression models were used on this patient cohort to predict return–to–activity time. Consequently, an analysis of feature importance was conducted after fitting each model. Results: OxSport clinical practice met standard (100%) in 3/5 criteria. The criteria not met were patient waiting times and documentation of all bone stress risk factors. Importantly, analysis of patient demographics showed that of the population with complete bone stress risk factor assessments, 53% were positive for modifiable bone stress risk factors. Lastly, linear regression analysis was utilized to identify demographic factors that predicted return–to–activity time [R2 = 79.172%; average error 0.226]. This analysis identified four key variables that predicted return-to-activity time: vitamin D level, total hip DEXA T value, femoral neck DEXA T value, and history of an eating disorder/disordered eating. Furthermore, random forest regression models were employed for this task [R2 = 97.805%; average error 0.024]. Analysis of the importance of each feature again identified a set of 4 variables, 3 of which matched with the linear regression analysis (vitamin D level, total hip DEXA T value, and femoral neck DEXA T value) and the fourth: age. Conclusion: OxSport clinical practice could be improved by more comprehensively evaluating bone stress risk factors. The importance of this evaluation is demonstrated by the population found positive for these risk factors. Using this cohort, potential bone stress risk factors that significantly impacted return-to-activity prognosis were predicted using regression models.

Keywords: eating disorder, bone stress risk factor, femoral neck stress fracture, vitamin D

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Authors: A. Bardey, P. James

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With the rise of fast-fashion, over consumerism and overproduction, the fashion industry is believed to be one of the most polluting industry. It is a matter of importance today to further understand the factors involved in green consumerism to enhance sustainable fashion. One of the critical issues in also evaluating green consumerism, particularly in fashion, is the attitude-behaviour gap. Indeed, many consumers report a positive attitude towards sustainable fashion consumerism, but this attitude is not always actioned into behaviour. This study aims to further investigate the attitude-behaviour gap in sustainable fashion consumerism. S triangulation of qualitative and quantitative methods was used. Focus groups were used to gain opinions and understanding of the barriers to sustainable fashion consumption. A quantitative online questionnaire was then used to quantify the barriers identified in Study 1 and measure their influence on the attitude-behaviour gap. The results suggest that knowledge about sustainable fashion is the key factor in the attitude-behaviour gap in sustainable fashion consumerism. Accessibility was also identified as a factor, but this relationship is more complex. It is suggested that knowledge is the main factor in the attitude-behaviour gap and that once knowledge is controlled for, accessibility will become a main factor. The present study is the first one to identify the factors involved in sustainable fashion consumerism.

Keywords: fashion, consumer behaviour, sustainable consumerism, attitude-behavioural gap

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Authors: Elchin Hajiyev, Afet Memmedova Dadash, Sabina Hajiyeva, Aynur Karimova, Ramiz Aliyev

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Although potatoes have a wide distribution range, the yield potential of varieties varies greatly depending on the region. Our country is made up of agricultural regions with very different environmental characteristics.In this case, we cannot expect the introduced varieties to show the same adaptation to the different conditions of our country. For this reason, in our country, varieties with high general adaptability should be used, rather than varieties with special adaptability in certain areas. Soil salinization has become a global problem.Increased salinity has a serious impact on food security by reducing plant productivity. Plants have protective mechanisms of adaptation to salt stress, such as the synthesis of physiologically active substances, resistance to antioxidant stress and oxidation of membrane lipids. One of these substances is free proline. Our study revealed genetic variation in proline accumulation among samples exposed to stress factors.Changes in proline content under stress conditions were studied in 50 samples. There was wide variation across all treatments.The amount of proline varied between 7.2–37.7 μM/g under salinity conditions.The lowest rate was in the SF33 genotype (1.5 times more than the control (2.5 μM/g)).The highest level of proline under the influence of salt stress was in the SF45 genotype (7.25 times higher than the control (32.5 μM/g)). Our studies have found that the protective system reacts differently to the influence of stress factors. According to the results obtained on the amount of proline, adaptation mechanisms must be more actively activated to maintain metabolism and ensure viability in sensitive forms under the influence of stress factors. At high doses of the salt stressor, a tenfold increase in proline compared to the control indicates significant damage to the plant organism as a result of stress.To prevent damage to the body, the antioxidant system needs to quickly mobilize and work at full capacity in adverse conditions. An increase in the dose of the stress factor salt in our study caused a greater increase in the amount of free proline in plant tissues. Considering the functions of proline as an osmoprotector and antioxidant, it was found that increasing its amount is aimed at protecting the plant from the acute effects of stressors.

Keywords: genetic variability, potato, genotypes, proline, stress

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