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Al x CoCrCuFeNi high entropy alloys were synthesised through mechanical alloying and spark plasma sintering. Different alloys were produced by varying the aluminium content (x = 0.5, 1.5, 2.5 and 4). The influence of the milling duration on the evolution of microstructure, constituent phases and morphology was studied. Milling time increasing resulted in grain refinement and higher solid solution homogenisation characterised by a high internal strain. As a consequence of aluminium addition, the materials’ microstructure evolved from FCC and BCC phases to FCC, BCC and ordered BCC phases. Both mechanical alloying and SPS conditions as well as aluminium content let to grain refinement and mechanical properties variations. In particular, hardness increased with increasing the aluminium content. The aluminium percentage and the consequent phases evolution is responsible for the microstructural stability at high temperatures.

Hydrodynamics of bubble column in the presence of different collectors was investigated by recurrence quantification analysis (RQA). By measuring the local pressure fluctuations of the gas-liquid bubble column by a piezo-resistive sensor and transforming the data to the state space, the recurrence plots were generated. Then, using the RQA, recurrence rate, determinism, and entropy of the plot were calculated. The RQA allows characterizing the flow regime and investigating the effect of adding various collectors, such as amine and ester, in square bubble columns. The results showed that determinism and entropy are sensitive parameters to detect the hydrodynamic changes in the bubble column. Furthermore, the transition range from homogeneous to heterogeneous regime was detected for tap water–air (4.4–5 cm/s), 50 ppm amine aqueous solution–air (4.4–5 cm/s), and ester aqueous solution–air (2.5–3.5 cm/s) systems. By examining the effect of adding collectors, it was found that entropy performs much better in detecting the changes in the hydrodynamics of the bubble column. For example, by adding 5 ppm ester to water, entropy changed 2.5 times more than determinism. As a result, entropy can be considered as the proper recurrence parameter for investigating the hydrodynamics of bubble columns.

This study investigated the impact of corporate sector variables on energy supply and demand in OECD countries. In the first stage of the investigation, a panel nonlinear model was employed to assess the effects of financial corporation debt to equity (FCDE), non-financial corporation debt to surplus (NFCDS), and banking system leverage on the contribution of renewable energy to primary energy. In the second stage, the influences of these independent variables on geo biomass, hydro, solar, and wind energy consumption were investigated. The findings demonstrate that FCDE and NFCDS are the firm-specific factors that influence renewable energy supply in the long run. The significant relationship between financial firm leverage and renewable energy highlights the fact that leverage is one of the main obstacles to further investment in renewable energy. Moreover, while banking system leverage has no impact on renewable energy’s contribution to primary energy, it has a discernible influence on solar and geo biomass energy consumption. Solar is the only renewable energy variable that is influenced by financial corporations and banking system leverage.

A method for the detection and diagnosis of various faults in chemical processes based on the combination of recurrence quantification analysis and unsupervised learning clustering methods is propo...

In this paper, a staggered, nonlinear finite element procedure is developed to solve the large-strain based coupled system of time dependent Ginzburg-Landau (GL) and thermoelasticity equations for ...

In this work, we present a tunable 24-GHz antenna array based on a CMOS-compatible 110-nm-thick nanocrystalline graphite film grown by plasma enhanced chemical vapor deposition. The film has a nominal bulk conductivity exceeding 16000 S/m (hence, greater than any graphene monolayer or industrially available graphene multilayer) but still able to show an outstanding modulation of its charge carrier density in the upper microwave spectrum. The manufactured layer was used to design, simulate, fabricate, and test a 24-GHz patch antenna array, with each radiating element having overall dimensions of just $\lambda _{0}/8\times \lambda _{0}$ /7. The fabricated array exhibits a measured maximum gain of about 3 dBi around 24 GHz (unbiased state), with a half-power beam width of only 14.5° (suitable in wireless links where a high directivity is envisaged). Spanning the dc bias voltage between -25 V and 25 V at 24 GHz, the gain can be tuned continuously between -1.5 dBi and 4 dBi, whereas the resonance frequency undergoes a maximum shift of 166 MHz. This voltage-dependent tuning of the gain represents a first step in developing carbon-based applications to control amplitude and phase simultaneously and independently. These results (never reported) demonstrate the big potential of nanocrystalline graphite for high-performance microwave components that are CMOS compatible (a highly desirable characteristic for high fabrication yield and large-scale production), with unprecedented tunability for next-generation high-capacity communications.

We propose a Generative Adversarial Network (GAN) optimized for noise reduction in CT-scans. The objective of CT scan denoising is to obtain higher quality imagery using a lower radiation exposure to the patient. Recent work in computer vision has shown that the use of Charbonnier distance as a term in the perceptual loss of a GAN can improve the performance of image reconstruction and video super-resolution. However, the use of a Charbonnier structural loss term has not yet been applied or evaluated for the purpose of CT scan denoising. Our proposed GAN makes use of a Wasserstein adversarial loss, a pretrained VGG19 perceptual loss, as well as a Charbonnier distance structural loss. We evaluate our approach using both applied Poisson noise distribution in order to simulate low-dose CT imagery, as well as using an anthropomorphic thoracic phantom at different exposure levels. Our evaluation criteria are Peek Signal to Noise (PSNR) as well as Structured Similarity (SSIM) of the denoised images, and we compare the results of our method versus recent state of the art deep denoising GANs. In addition, we report global noise through uniform soft tissue mediums. Our findings show that the incorporation of the Charbonnier Loss with the VGG-19 network improves the performance of the denoising as measured with the PSNR and SSIM, and that the method greatly reduces soft tissue noise to levels comparable to the NDCT scan.

In this article, bistable laminates are statically and dynamically studied under the existence of nonlinear magnetic force. The bistable laminates with magnetic forces are considered as a nonlinear system for vibration energy harvesting. First, a semi-analytical model was established based on the energy approach for the bistable plate together with magnets. The magnetic force versus distance was measured, and then, an equation was fitted to the experimental data. The damping of the whole system was determined experimentally, and Rayleigh damping coefficients were extracted and used in all models. Next, a finite element model of the whole system was developed to compute the dynamic response of the system under different base excitations. Finally, a test rig was constructed, and the system responses were measured under various base excitations. The dynamic snap-through of the bistable laminate under magnetic forces was also measured and compared with the results obtained from the semi-analytical and finite element model. The analysis shows that adding a magnetic force will reduce the amplitude of base excitation that is needed for dynamic snap-through for %28.6. The analysis shows that the bistable plate with a magnetic force can be a good candidate for energy harvesting because the nonlinear magnetic forces under certain conditions reduce the snap-through force and consequently increase the harvested energy. This is because of the fact that the presence of the magnetic forces allows the system to vibrate between its two stable configurations under lower base excitation amplitudes.

The growing diversity in demand and the shorter life cycle of products necessitate integrating policies of design, production, and marketing to decide on which products, with which attributes shoul...

AlCrFeCoC high entropy alloy was synthesised through mechanical alloying and spark plasma sintering. The milling time had a strong influence on the particles shape and structure and consequently on...

This study concerns the effect of bicrystal spatial orientation on the iron Σ5 boundary under nanoindentation tests. The orientation of the bicrystal is changed relative to the indenter by the para...

In the current study, selenium particles were loaded into poly(e-caprolactone)/gelatin nanofibrous matrices in order to fabricate a potential wound dressing. The mats were produced by electrospinning of poly(e-caprolactone)/Gelatin (1:1 (w/w)) solution supplemented with 1 and 10 % (w/v) of selenium particles. Prepared wound dressings were investigated regarding their morphology, mechanical properties, surface wettability, water-uptake capacity, water vapor permeability, porosity, blood compatibility, microbial penetration test and cellular response. Dressings containing 1 % and 10 % selenium and selenium free mats were chosen to treat the full-thickness excisional wounds in Wistar rats. The study revealed that after 14 days, the wound closure of the mat containing 1 % selenium was about 95.5±6.38 % while wound closure of the negative control group was about 48.83±4.03 %. Our results showed the capability of nanofibrous containing selenium for successful wound treatment.

The interaction between the crack and the grain boundary has been investigated by molecular dynamics simulation. The focus of this research is to study fracture resistance of grain boundary in a th...

The isolation valves are crucial components of water distribution systems (WDS) that are used to shut down a segment of the network to repair or replace failed pipes. In this paper, an algorithm to...

The main goal of this study is to present a model to investigate the effect of nano-particles’ weight fraction on the friction coefficient of rough contact in the mixed-lubrication regime. Experimental testing involves pin-on-disk measurements of the friction coefficient with CuO nano-particles added to engine oil. Theoretical analyses involve developing a method for treating an EHL line contact with provision for surface roughness that takes into account the load-carrying capacity of surface asperities, lubricant, and nano-particles. Results show that theoretical and experimental results for friction coefficients are in good agreement. A parametric study is conducted to investigate effect of load, the geometry of the nano-particles, and their mechanical properties as well as their weight fraction on the friction coefficient.

Numerical methods have been proved to be useful tools for understanding different phenomena. In this paper, triggered furrow irrigation has been analyzed by means of numerical modeling. To this end, a special code is developed for simulation of triggered furrow irrigation system by coupling three-dimensional Richards’ equation and one-dimensional fully hydrodynamic form of Saint-Venant equations. The coordinate transformation technique was used for solving Richards’ equation that improves flexibility of model for simulation of water flow in irregularly shaped furrows. Furthermore, overland flow module benefits from high-resolution total variation diminishing scheme that avoids artificial oscillations commonly occurring on the advance water front. The code was validated against different analytical, numerical and experimental benchmarks. In all cases, the accuracy of model was acceptable. The code was subsequently employed to simulate all phases of triggered furrow irrigation system (including advance and redistribution phases) on a field cultivated with wheat. Finally, Taguchi technique was employed to deduct proposals to optimize performance of triggered furrow irrigation system in terms of sensor position, triggering and cutoff thresholds and inflow rate. It was concluded that optimal performance of triggered irrigation system was obtained when the water content sensor was installed close to the furrow, providing that triggering and cutoff thresholds were set as − 15 and − 3 m (close to field capacity) and inflow rate was 1 L s−1.

The aim of this paper was to evaluate the surface temperature distribution in several single and double jersey weft-knitted fabrics. Plain knitted fabrics as well as those with, double cross-tuck, cross-tuck, double cross-miss, and cross-miss pattern together with plain rib and interlock structures were under consideration in term of their structural differences. In order to investigate the temperature distribution in produced samples, all the fabrics were placed on a 35?C adjusted hot plate instrument and thermal images were captured by an infrared thermal camera. The results revealed that the presence of tuck stitches in single jersey weft-knitted fabrics increase the air permeability due to the increasing the fabrics? porosity, which in turn leads to decrease their thermal resistance as compared with plain knitted structure. On the other hand, addition of miss stitches in single jersey knitted structures would decrease the thickness of fabrics and improves their heat transfer ability. The obtained results, from rib and interlock knitted structures, suggested their lower heat conductivity in comparison to the single jersey knitted samples.

© 2019 Elsevier Ltd. The integration of a natural gas to liquids (GTL) process with ammonia and urea synthesis units was conducted to utilize the emitted CO2 of the GTL process for the urea synthesis. The feedstocks of the ammonia synthesis unit including hydrogen and nitrogen were provided by a polymer electrolyte membrane (PEM) electrolyzer and air separation unit (ASU) of the GTL process, respectively. The required power for the PEM modules was assumed to be supplied by the surplus generated power of the GTL process. To enhance the overall carbon efficiency and profitability of the three processes, the emitted CO2 from the GTL process was utilized in the urea synthesis unit. Multi-objective optimization approach was conducted to determine the optimal values of carbon efficiency and wax production rate of the GTL process. Objective functions were calculated by response surface methodology with second-order polynomial regression. The degrees of freedom were defined as follows: Unpurged ratio of recycled tail gas from Fischer-Tropsch (FT) reactor, recycle ratio of the GTL tail gas to the FT reactor, CO2 removal percentage from the GTL process synthesis gas (syngas) section, steam to carbon ratio to pre-reformer, molar flow of feed to the ammonia synthesis unit, and CO2 intake to the urea unit. The presented integration results in the production of about 434,000»tonnes/year urea in addition to the FT-derived products. 13.71% (37»tonnes/h) of the produced CO2 in the GTL process is utilized in the urea production unit and the profitability of the integrated process is enhanced by 8%.

AlxCoCrCuFeNi high-entropy alloys were synthesised through mechanical alloying and spark plasma sintering. Different alloys were produced by varying the aluminium content (x = 0.5, 1.5, 2.5 and 4). The influences of the milling duration on the evolution of microstructure, constituent phases and morphology were studied. Increasing milling time resulted in grain refinement and higher solid solution homogenisation characterised by a high internal strain. As a consequence of aluminium addition, the microstructure of materials evolved from face centered cubic (FCC) and body centered cubic (BCC) phases to FCC, BCC and ordered BCC phases. Both mechanical alloying and SPS conditions as well as aluminium content led to grain refinement and variations of mechanical properties. In particular, hardness increased with increasing aluminium content. The aluminium percentage and the evolution of consequent phases are responsible for the microstructural stability at high temperatures. In addition, with Al content increase, the further synergy of strength and ductility along with a more pronounced strain hardening was obtained.

A coupled crystal plasticity and phase field modeling framework is employed to simulate polycrystalline grain growth via static strain induced grain boundary migration. Specifically, the effect of the average grain size as a microstructural length scale on the development of microstructure and texture in columnar–grained aluminum polycrystal is examined. During annealing, subsequent to plastic tensile straining, a nearly normal grain growth regime is observed for comparatively small microstructural length scales. However, for comparatively large microstructural length scales, abnormal grain growth and development of a specific texture emerge. Hence, grain growth is found to transition from normal to abnormal by enlarging the microstructural length scale. These observations are attributed to the fact that the competing driving forces for grain boundary migration scale differently with the microstructural length scale. In addition, for the case of large microstructural length scale, a transition from abnormal to normal grain growth at later annealing times is observed. This observation is attributed to the weakening of the strain induced boundary migration effects due to the initial rapid reduction of dislocation content.

Purpose This study aims to design a proper supply chain network for the vaccine industry in Iran, which considers several features such as uncertainties in demands and cost, perishability of vaccines, wastages in storage, limited capacity and different priorities for demands. Design/methodology/approach This study presents a mixed-integer linear programming (MILP) model and using a robust counterpart approach for coping with uncertainties of model. Findings The presented robust model in comparison with the deterministic model has a better performance and is more reliable for network design of vaccine supply chain. Originality/value This study considers uncertainty in the network design of vaccine supply chain for the first time in the vaccine context It presents an MILP model where strategic decisions for each echelon and tactical decisions among different echelons of supply chain are determined. Further, it models the difference between high- and low-priority demands for vaccine.

Introduction Halitosis as a common dental problem results in psychological social problems and relates to many factors. The aim of this study was to evaluate the prevalence of halitosis and its associated factors among students aged from 14 to 18 years in Kermanshah in 2015. Materials and methods The study was conducted in high school students of Kermanshah city in 2015. The questionnaire including questions about bad breath and other associated factors (demographic information, background diseases, oral and dental problems, decay-missing-filled (DMF) index, etc.) was completed by students or determined by the examiner. Organoleptic evaluation was conducted. Prevalence of organoleptic and self-reported halitosis and related factors was reported. The relationship between malodor and variables was evaluated and the most important factor was determined by multiple logistic regression analysis. The diagnostic agreement between self-perception and organoleptic halitosis was assessed using Kappa coefficient as well. Results The prevalence of halitosis in the organoleptic evaluation was 29.75% and higher in boys (32.6% male vs. 25.2% female) and 27.47% in self-perception (32.9% male vs. 19% female). The diagnostic agreement between organoleptic and self-perception halitosis was moderate or poor. Among the studied factors, the most important factor related to the organoleptic evaluation of halitosis was DMF≥4 (P

The effect of anisotropic grain boundary energy on the kinetics of stressed grain growth is investigated by two-dimensional phase field simulations. The simulations are performed for a two-dimensional representative volume element of polycrystalline copper with elastic cubic symmetry under both uniaxial elongation and shear loading with elastic strains in the order of a few thousandths. The Read-Shockley relation for the misorientation–dependence and the cubic symmetry for the inclination–dependence of grain boundary energy are assumed. The simulation results have generally shown that the misorientation–dependent anisotropy, compared to the inclination–dependent anisotropy, significantly affects the evolution of microstructure and texture during stressed grain growth. Particularly, the misorientation–dependent anisotropy of grain boundary energy results in (i) the elongated morphology of grains in the evolved microstructure; (ii) the aggregation of grains with similar orientations in the evolved microstructure; (iii) the strengthening of lower–misorientation angle grain boundary segments; and hence (iv) decelerating the overall rate of stressed grain growth and texture evolution and (v) decelerating stress relaxation under constant–strain loading. These results are based on the assumption that the isotropic grain boundary energy is equal to the high angle grain boundary energy of the misorientation–dependent grain boundary energy and the inclination–dependent grain boundary energy varies sinusoidally around the isotropic grain boundary energy.

Effect of the initial orientations of ferrite grains on the strain localization and consequently deformation behavior in DP780 steels was studied by employing experimental examination and numerical simulations. Based on dislocation density-based crystal plasticity finite element simulation, it was revealed that the initial orientation of ferrite grains plays a key role in the evolution of shear bands and consequently on the ductility of dual phase steels. In other words, the stored dislocation density within each ferrite grain and consequently the energy absorption capacity of DP steels depends on its initial orientation. Moreover, a qualitative comparison between simulated data and measured texture maps exposes the validity of the analysis.

In the present study, residual stress is measured in fiber-reinforced SWCNT/epoxy at weight fractions of 0.1% and 0.5% with a cross-ply layup on a micro-scale. The mechanical properties of the SWCNT/epoxy composites were determined by tensile testing and the Young's modulus of the epoxy increased moderately with the addition of CNTs. The micro-residual stress of the cross-ply CF/epoxy and CNF-reinforced CF/epoxy laminates were measured using a new experimental approach. The micro-hole was milled by laser beam and the surface displacement was recorded by SEM after milling. In order to determine the residual stress from the recorded strain, the calibration matrix was calculated using the finite element method. The residual stress was obtained at a certain hole depth of specimens. The reliability of this approach was assessed by comparing the residual stress measurements from this method and from the standard hole-drilling method. The experimental results of the present approach confirmed that laser hole drilling SEM-DIC has excellent potential as a reliable method for measuring residual stress in polymer nanocomposites. Generally, CNT agglomerates, especially in high weight fractions, increased the micro-residual stress. An analytical method based on classical theory was used to calculate the residual stress and was compared with the experimental results. Good agreement was found between the results of the analytical methods and the experimental measurement.

The aim of this study was simulating the temperature distribution in course-wise extended weft-knitted fabrics by considering different extension levels. Accordingly, three types of weft-knitted fabrics structured in plain single jersey, plain rib, and interlock patterns were prepared using an electronic flat knitting machine. The fabrics were then exposed in a course-wise manner to three different extension levels (0%, 15%, and 30%) from which their heat transfer features at an extended state could be measured, by using the hot plate instrument and an infrared thermal camera. For the theoretical evaluation of temperature distribution, the fabrics’ corresponding geometrical unit cells were established in a finite element software environment. There was an acceptable agreement between the experimental and modeling results. It was also shown that applying different extension levels could significantly affect the knitted fabrics’ temperature distribution.

Our research objective was to obtain a fundamental understanding of how ITO thin films layered on flexible polyethylene terephthalate (PET) substrates fail due to tensile, shear, and bending loading conditions. In our approach, we employed a nonlinear finite-element (FE) approach coupled with dislocation-density crystalline and hypoelastic material models and fracture approaches tailored for channel (film) cracking and interfacial delamination. These predictions were validated with mechanical experiments and characterization at different physical scales. Failure to strain and fracture predictions were used to account for interrelated mechanisms, such as channel and interfacial cracking nucleation and propagation along cleavage planes, interfaces, and within layers. Our predictions indicate that interfacial delamination occurred when channel cracks transitioned to interfacial cracks at the ITO/PET interface for tensile loading conditions. Furthermore, the thin film system, when subjected to three-point bending and shear loading conditions was more resistant to failure in comparison to systems subjected to tensile loading conditions.

BACKGROUND: Retinal degeneration causes blindness, and cell replacement is a potential therapy. The purpose of this study is to formation of pigmented neurospheres in a simple medium, low-cost, high-performance manner over a short period of time while expressing markers of RPE cells and the activation of specific genes of the pigment cells. Also, these neurospheres have the ability to produce a monolayer of retinal pigment epithelium-like cells (RPELC) with the ability of photoreceptor outer segment phagocytosis. METHODS: BMSC were isolated from pigmented hooded male rats and were immunoreactive to BMSC markers, then converted into neurospheres, differentiated into pigmented spheres (PS), and characterized using Retinal pigment epithelium-specific 65 kDa protein (RPE65), Retinaldehyde-binding protein 1 (CRALBP) and orthodenticle homeobox 2 (OTX2) markers by immunocytochemistry, RT-PCR and RT-qPCR. The PS were harvested into RPELC. The functionality of RPELC was evaluated by phagocytosis of fluorescein-labeled photoreceptor outer segment. RESULTS: The BMSC immunophenotype was confirmed by immunostained for fibronectin, CD90, CD166 and CD44. These cells differentiated into osteogenic and lipogenic cells. The generated neurospheres were immunoreactive to nestin and stemness genes. The PS after 7–14 days were positive for RPE65 (92.76–100%), CRALBP (95.21–100%) and OTX2 (94.88–100%), and after 30 days RT-PCR, qPCR revealed increasing in gene expression. The PS formed a single layer of RPELC after cultivation and phagocyte photoreceptor outer segments. CONCLUSION: Bone marrow stromal stem cells can differentiate into functional retinal pigmented epithelium cells in a simple, low-cost, high-performance manner over a short period of time. These cells due to expressing the RPELC genes and markers can be used in cell replacement therapy for degenerative diseases including age-related macular degeneration as well as retinitis pigmentosa.

Unsustainable groundwater withdrawal is a major challenge facing semi-arid and arid regions of the world, where groundwater is the primary source of irrigation water. Conversion of some agricultural land to fallow land is one of the possible solutions to reduce the groundwater withdrawal to bring it to safe yield. Such a solution has a negative economic impact. In this study, we have developed an optimization approach that can use used to identify the size (and type) of the agricultural area to be fallowed to ensure sustainable groundwater use for irrigation with as little economic impact as possible. This approach is based on the concept of profit productivity, which relies on Landsat imageries to calculate crop yield and irrigation water withdrawal, and available in-situ data to calculate energy cost. We have applied this approach to the Neyshabour basin in Iran that has been experiencing unsustainable groundwater withdrawal for the last 30 years. Our sample results indicate that in order to ensure sustainable groundwater withdrawal with minimum economic impact, 4% of the agricultural land needs to be converted to fallow land by fallowing most of the agricultural land used for growing tomatoes.

Advance and recession curves are of great importance for assessing the performance of border irrigation. In recent years, scaling techniques have helped to reduce the required measurements and to provide formulation of soil–water relations. The purpose of this study was to develop an invariant equation for calculating advance and recession curves in border irrigation using scaling techniques. The kinematic wave model and the Philip infiltration equation were used to simulate border irrigation. Scale factors were defined such that the kinematic wave equation remained independent of the initial and boundary conditions of the soil. Scaled advance and recession curves showed certain patterns, which led us to introduce a power and a binomial equation for advance and recession phases, respectively. The scaled equations were applied on 25 vegetated and non‐vegetated borders. Four performance indices were calculated for each border, including application efficiency (Eₐ), deep percolation ratio (DPR), tail water ratio (TWR) and water requirement efficiency (Eᵣ). Results showed that the maximum differences between measured and estimated values were 4% for Eₐ, 9% for DPR and 4% for Eᵣ. Considering the simplicity and soil‐condition independence of the proposed method, it can be concluded that scaled advance and recession curves could provide a reasonable estimate of border irrigation performance. © 2019 John Wiley & Sons, Ltd.

We analyzed how b.c.c. semi-coherent interfaces, within an h.c.p. matrix, have a central effect on the fracture of these multi-phase aggregates. We obtained 36 unique Orientation Relations (ORs) related to semi-coherent interfaces between the hydrides and the parent matrix, and calculated interfacial misfit strains between the matrix and hydride crystalline structures. We then coupled these microstructural interactions to a dislocation-density framework with a fracture nucleation and propagation approach to understand and predict different failure scenarios. The analysis indicates that misfit strains have a dominant mechanistic effect that is essential for an understanding of multi-phase crystalline aggregate behavior that spans different length scales.

In this paper, mistuning of bladed-disk systems is investigated. The blades are considered as continuous Euler-Bernoulli beams with transverse and longitudinal degrees of freedom. The governing equations of motion for the tuned and mistuned bladed disk systems are derived and discretized by use of Galerkin method. The obtained equations have time-varying coefficients and cannot directly be used for calculating the system critical speeds and Campbell diagram. For the tuned case, by use of Coleman and complex transformations one can transform the time varying system to a time-invariant system. Further transformations are required for the mistuned system to change into a time-invariant system. Next, a four-bladed disk system supported by bearings was considered. The modal analysis was performed and the critical speeds and the Campbell diagram were calculated. The results indicate that both coupled modes and conjugate modes appear in the Campbell diagram which are changing with the rotating speed. Finally, a probabilistic analysis was performed on the mistuned parameters by use of Monte Carlo method. It was found that the disk dominant modes are insensitive to the various mistuning realizations. However, the blade dominant modes are sensitive to the mistuning parameters and have a coefficient of variation one order of magnitude less than the mistuning coefficient of variation. It was also seen that the probability density functions of whirl speeds for different mistuned properties are able to be considered Gaussian.

In this paper, the effects of Thermal Barrier Coating (TBC) thickness on temperature and stress distribution over the blade body are investigated. TBC acts like an insulation layer that increases the temperature gradient between the hot gases and the blade body. For this purpose, a 3D model of the blade body and TBC is created. Material of the substrate is considered as temperature-dependent Elastoplastic material, which its plasticity behavior is extracted point by point from the stress-strain curve. TBC is modeled as an elastic body, and the boundary conditions are applied as heat transfer coefficient. The significant point is that while the TBC thickness increases, the substrate thickness decreases respectively so that the total geometry of the whole blade remains constant in order to keep its aerodynamic behavior unchanged. Results show that increasing TBC thickness, affects significantly on the temperature distribution of the blade as some regions its surface experience a 100 °C collapse in temperature by increasing TBC thickness from 100 to 500 μm. In addition, the temperature of coolant which emerges from the top of the blade, is affected by TBC thickness, especially in the microholes near the leading and the trailing edges. Using stress evaluation, the critical region near the blade surface, which can be considered as an eligible point for crack nucleation, can be investigated. Results show that increasing TBC thickness from 100 to 500 μm, leads to 40 times decrease in the equivalent plastic strain.

This paper investigates the offline neural network based-fault tolerant control for an aircraft that suffers vertical-tail damage. First, the damaged model of the aircraft is obtained, and the external disturbance is estimated by a disturbance observer then, an optimal control scheme is proposed to control the aircraft in nominal condition. This optimal control scheme is developed into faulty condition by the offline neural networks. The simulation results show the effectiveness of the proposed method in comparison to the existing methods in the literature.

Estimation of discharge hydrograph may be needed at river gauging stations where discharge is computed by converting water stage using a stage-discharge relation (a rating curve) or multiplying mean velocity by flow cross-sectional area. The mean velocity is computed by converting the measured maximum velocity to mean velocity using a conversion factor. Estimating the velocity conversion factor at stations where measured discharge data are insufficient remains a challenge. This study develops a novel method for determining the conversion factor by combining the entropy velocity profile, a data-driven technique, and a one-dimensional (1-D) flood routing model, and thus develops a method to determine discharge at the weak gauging sites. The method was used with two different assumptions: constant velocity factor and velocity factor depending on the aspect ratio. Results showed that this method optimally estimated the conversion factor.

Due to the entrance of pollutants in different branches of the river network, it is essential to study contaminant transport at the river confluences. In the present study, it was attempted to investigate the conservative pollution transport at channel confluence by operating a series of experiments in the laboratory flume. In the designed laboratory model, two branches, with different widths of 45, 25 cm, were intersected and a channel confluence was created. Five entrance discharges and three initial contaminant concentrations, introduced using a linear feeder, were chosen as experimental variables. Conservative tracer of sodium chloride solution was used, and the electrical conductivities were measured at eight locations of the main channel and upstream branches with 2 seconds interval. Junction zone was assumed as a control volume, and by applying mass equilibrium to it, a new mathematical model was extracted. It was observed that there is concentration fluctuation in the falling limbs of the experimental breakthrough curves of the junction zone; however, it was diminished by downstream motion. Moreover, the observed pollution graphs had double peak points which changed to a single point with an increase of distance from the confluence position. Operation of the presented model was investigated by variation of its parameters. It was found that the contaminant residence time parameters of the confluence zone have the most significant influence in the simulation of the analytical model. Additionally, it was observed that the values of Gaussian distribution of the upstream branches could displace the position of pulses of resultant breakthrough curves or can overlap them. Moreover, the model performance was examined using statistical goodness of fit parameters like Nash–Sutcliffe, R2, and mean absolute error (MAE). Their values were calculated as 0.88, 0.91, 66.88 (ppm), respectively.

Since collagen is naturally a main extracellular matrix protein, it has been applied widely in skin’s tissue engineering scaffolds to mimics the characteristics of extracellular matrix for proper transplantation of living cells. However, there are challenges that come with application of this natural polymer such as high solubility in aqueous environments which requires further consideration such as chemically cross-linking in order to stabilization. But these treatments also affect its functionality and finally cellular behaviors on scaffold. In this research we evaluated the suitability of collagen nanofibers versus collagen nanoparticles for cell adhesion and viability on glutaraldehyde cross-linked scaffolds. Appling a dual-pump electrospining machine a blend PCL-Gelatin from one side and collagen nanofibers or collagen nanoparticles from the other side were collected on the collector. The fabricated scaffolds were characterized by scanning electron microscopy, contact angle, and mechanical analysis. The cell viability, adhesion and morphology were studied respectively using MTT assay, hoechst staining and scanning electron microscopy. The results indicated significantly improvement of cell viability, adhesion and better spreading on scaffolds with collagen nanoparticles than collagen nanofibers. It seems changes in surface morphology, viscoelastic moduli and swelling ability following cross-linking with glutaraldehyde in scaffold with collagen nanoparticles are still favorable for cellular proliferation. Based on these results, in the case of glutaraldehyde cross-linking, application of collagen nanoparticles rather than collagen nanofibers in tissue regeneration scaffolds will better mimic the extracellular matrix characteristics; and preserve the viability and adhesion of seeded cells.

In this paper, a feedback linearization based fault-tolerant control for affine non-linear systems with actuator fault is studied. Based on the feedback linearization, an affine nonlinear system is transformed into a linear system. By using the linear quadratic regulator (LQR), optimal control policy is obtained in fault-free condition and then using adaptive compensator, the effect of constant and time-varying faults is alleviated. Finally, with a simulation example, the effectiveness of the proposed method is demonstrated.

In this study, a nanobiocomposite scaffold was fabricated by combining sodium alginate, polyvinyl alcohol, silk fibroin and magnesium hydroxide nanorods. The structural characteristics and properties of the scaffold were identified by field emission scanning electron microscope (FE-SEM), thermogravimetric analysis (TGA), Fourier-transformed infrared (FT-IR) and energy dispersive X-Ray (EDX) analyses. To introduce the application, biocompatibility, mechanical properties and biological activity of the scaffold were obtained. The composite was found to have high porosity, no cytotoxicity, excellent cellular adaptation, and most importantly Mg(OH)2 nanorod had antibacterial activity and inhibited the growth of bacteria. In addition, silk fibroin and alginate increased the scaffold strength due to mechanical tests. Hemolytic assay and cell metabolic activity of this novel nanobiocomposite showed that the hemolytic effect was less than 8% and about 92% of cells survived. Due to considerable biological activities and acceptable mechanical properties, the mentioned nanobiocomposite can be considered as a scaffold for possible use in wound dressing, tissue engineering and drug delivery systems.

In this paper, we present a coplanar patch antenna (CPA), based on a graphene monolayer deposited on a thin film of zirconium-doped hafnium oxide ferroelectric (HfZrO), working at 24 GHz. The proposed antenna has been designed, simulated, fabricated and measured according to the requirements of an indoor localisation system based on a Frequency-Modulated Continuous-Wave (FM-CW) radar in the 24 GHz (24-24.25 GHz) ISM band with small codified tags to add identification functionality. The graphene CPA (GCPA) shows a 3 dB-enhancement of the gain in the direction of maximum radiation when applying a DC bias of -25 V. Then, a realistic case of study with a $4\times 4$ array is presented, showing the feasibility of the G-CPA for a 24 GHz-radar suitable for next-generation 5G telecommunications systems.

The economic and environmental impact to produce bioethanol from biomass is investigated in this paper. Accordingly, a partial equilibrium model is employed to study large scale bioethanol production on the Malaysian agricultural sector and gauge secondary effects on the agricultural markets. The model shows the palm oil mills can produce bioethanol competitively and blend with gasoline fuel because the mills utilize the waste biomass created onsite and thus avoid the hauling costs. Furthermore, a large bioethanol industry would help Malaysia reduce its GHG emissions as biomass recycles carbon from the atmosphere and would help Malaysia meet its commitments in the Paris Agreement. A large bioethanol industry also creates a little derived demand for waste biomass that expands the agricultural industry, reduces agricultural prices, raises agricultural employment, and leads to greater forestation as landowners clear rainforests to expand oil palm plantations.

Large datasets computing is a research problem as well as a huge challenge due to massive amounts of data that are mined and crunched in order to successfully analyze these massive datasets because they constitute a valuable source of information over different and cross-folded domains, and therefore it represents an irreplaceable opportunity. Hence, the increasing number of environments that use data-intensive computations need more complex calculations than the ones applied to grid-based infrastructures. In this way, this paper analyzes the most commonly used algorithms regarding to this complex problem of handling large datasets whose part of research efforts are focused on reducing dimensional space. Consequently, we present a novel machine learning method that reduces dimensional space in large datasets. This approach is carried out by developing different phases: merging all datasets as a huge one, performing the Extract, Transform and Load (ETL) process, applying the Principal Component Analysis (PCA) algorithm to machine learning techniques, and finally displaying the data results by means of dashboards. The major contribution in this paper is the development of a novel architecture divided into five phases that presents an hybrid method of machine learning for reducing dimensional space in large datasets. In order to verify the correctness of our proposal, we have presented a case study with a complex dataset, specifically an epileptic seizure recognition database. The experiments carried out are very promising since they present very encouraging results to be applied to a great number of different domains. This work was partially funded by Grant RTI2018-094283-B-C32, ECLIPSE-UA (Spanish Ministry of Education and Science), and in part by the Lucentia AGI Grant. This work was partially funded by GENDER-NET Plus Joint Call on Gender an UN Sustainable Development Goals (European Commission - Grant Agreement 741874), funded in Spain by “La Caixa” Foundation (ID 100010434) with code LCF/PR/DE18/52010001 to MTH.

Nanocrystalline-twinned materials exhibit significantly higher strength and ductility than nanocrystalline face-centered cubic (f.c.c.) materials without twins. In this investigation, a dislocation-density-based multiple-slip crystalline constitutive and a nonlinear finite element formulation have been used to understand how twin volume fractions, grain and twin orientations and texture, dislocation-density accumulation, and large inelastic strains affect the competing effects of strengthening and toughening mechanisms in nanotwinned materials. The predictions have indicated that grain and twin orientations with respect to different loading axes significantly affect how dislocation densities evolve, and that this has a dominant effect on both ductility and strength. The predictions were validated with experiments pertaining to nanotwinned f.c.c. copper aggregates. The validated predictions can potentially be used as design guidelines for optimizing the mechanical behavior of nanotwinned crystalline materials, such that behavior can be mitigated and controlled at the nanocrystalline scale.

This paper concerns with the problem of natural convection heat transfer inside an industrial oven with an internal plate. The model is simulated numerically as a square cavity with an isolated plate laid horizontally or vertically inside it. Different ranges of Rayleigh number from laminar to turbulent flow regimes were investigated numerically and inherent flow structures and the amount of transferred heat were obtained. The governing Reynolds-averaged Navier-Stokes and energy equations are discretized and solved applying finite-volume method. Moreover, a two-layer zonal model is applied for near-wall turbulent properties. Comparing the present results with similar previous studies and experimental data shows that the employed zonal model is more accurate than other existing turbulent models. Our results also demonstrate that the total rate of heat transferred by a cavity with internal isolated plate is always lower than that of a bare cavity. As the distance of internal plate from the cavity wall decreases, its effect on the reduction of overall heat transfer increases accordingly. We also determined a distance between the plate and the cavity wall with less than 2% change in relative Nusselt number and deduced that the maximum distance of vertical plate is always greater than that of the horizontal plate at each Rayleigh number. Furthermore, a dead zone is created between the hot wall and the plate with low velocities, the temperatures close to the hot wall temperature, and very weak circulation, which can significantly reduce the overall heat transfer in the cavity. The results of this work can be used in glass industries and reduction of heat loss in industrial ovens by placing the glass sheets inside them in appropriate position.

This study aimed at producing the biodegradable composite from lignocellulose nanofibers (LCNFs) and Pebax®thermoplastic elastomer. For this purpose, LCNFs at different levels of 0, 1, 3, and 5% were considered. The LCNFs were prepared by benzyl alcohol and then mixed with Pebax®. The liquid phase of the LCNFs and soluble polymer was prepared and then the masterbatches were mixed in an internal mixer (Model 815802, Brabender, Germany). The mixtures from the internal mixer were put into a hot press and test samples were compress-molded. The physical properties results indicated that water absorption and thickness swelling decreased by the addition of more amount of LCNF. By the addition of LCNFs to polymer, the tensile strength and modulus and impact strength were increased compared to samples without LCNF. No regular trend of enthalpy changes was observed as the content of LCNF changed. When the LCNF concentration was increased to 5%, the crystallization temperature was increased. As the LCNF concentration increased to 3%, the glass transition temperature ( Tg) was decreased, whereas by incorporating more LCNFs, the Tgwas increased. The result of the Fourier transform infrared spectra showed the peaks at 1740 cm−1which indicated the presence of polyamide bonds. Also, new peaks were observed in the range of 1400–1500 cm−1that was probably related to the presence of C−C bonds of glucose at LCNFs chains.

In this study, the static and dynamic responses of bi-stable hybrid composite laminates [0/AL/90]T and [02/AL/902]T were scrutinized, and their behavior was compared to bi-stable pure composite laminates including [0/90]T and [02/902]T. The work consisted of an analytical study that was validated experimentally. An analytical method based on Hamilton’s principle was developed to investigate the static and vibration characteristics of the laminates. Experimentally, curvatures and out-of plane-displacement, and snap-through load were measured using a quasi-static loading on a universal testing machine. Further experimental analysis was performed to characterize the damping viscous ratio, natural frequency, and critical base excitation that cause the snapping between the two different stable shapes. The results show that the hybridization of bi-stable pure composite laminates has the potential to increase the stable curvatures and enhance the static load-carrying capability up to five times when compared to a pure bi-stable composite laminate of the same thickness. It was also observed that the hybridization of bi-stable pure composite laminates may result in a dramatic change in the dynamic response. The natural frequencies of bi-stable hybrid composite laminates are increased in comparison with bi-stable pure composite laminates. The critical base excitation required for snapping has increased significantly for the hybrid composite laminate. The qualitative and quantitative comparisons between the analytical and experimental results were very promising and they agreed well.

The potential application of Yttrium Oxide (Y2O3) in capacitive Micro-Electro-Mechanical Switches (MEMS) dielectric films is investigated. The electrical properties and the impact of electrical stress on capacitive switches have been investigated with the aid of Metal-Insulator-Metal (MIM) capacitors and MEMS capacitive switches in order to determine the suitability of this material for such application. The assessment in MIMs consisted of recording the current-voltage characteristics in order to determine the transport mechanisms and the charge injection by injecting electrodes during the charging process. The MEMS switches were employed to monitor the charge injection through the bridge during pull-in state and collection during the pull-up state. The process was performed under different stress conditions in order to determine the impact of stressing electric field intensity.

Pressure fluctuations were used for detecting the changes of mean particle size in fluidized beds by two online and accurate monitoring methods (recurrence and cross recurrence analysis (RA and CRA...

In this paper, a class of time-delay fractional optimal control problems (TDFOCPs) is studied. Delays may appear in state or control (or both) functions. By an embedding process and using conformable fractional derivative as a new definition of fractional derivative and integral, the class of admissible pair (state, control) is replaced by a class of positive Radon measures. The optimization problem found in measure space is then approximated by a linear programming problem (LPP). The optimal measure which is representing optimal pair is approximated by the solution of a LPP. In this paper, we have shown that the embedding method (embedding the admissible set into a subset of measures), successfully can be applied to non-linear TDFOCPs. The usefulness of the used idea in this paper is that the method is not iterative, quite straightforward and can be applied to non-linear dynamical systems.

Nonlinear optics (NLO) deserves special attention in new optical devices, making it possible to generate coherent light more efficiently. Among the various NLO phenomena the third-harmonic generation (THG) is at the core of the effective operating mechanism of broadband wavelength conversion, in all-optical devices. Here, we aim to understand how the third-order susceptibility and the electric field may be effectively effect on the localization properties of the light in the THG process when included in a two-mode cavity coherently perturbed by a classical field. We address a stable–unstable transition due to the combination effect of the aforementioned factors. We report a reliable evidence confirming the appearance of chaos in THG under suitable conditions. By tracing the signatures of adjacent-spectral-spacing-ratio (ASSR) distribution and participation ratio, we also find a critical point ( ϵ c , κ c ) = ( 3 . 1 , 0 . 35 ) for which a pronounced delocalized response is seen. This study may have profound findings for practical devices, and ushers in new opportunities for practical exploitation of the electric field and the third-order susceptibility effect in nonlinear optical devices.