Increasing Generation Number Research Articles

Josephson effect in a fractal geometry

The Josephson effect is a hallmark signature of the superconducting state, which, however, has been sparsely explored in non-crystalline superconducting materials. Motivated by this, we consider a Josephson junction consisting of two superconductors with a fractal metallic interlayer, which is patterned as a Sierpiński carpet by removing atomic sites in a self-similar and scale-invariant manner. We here show that the fractal geometry has direct observable consequences on the Josephson effect. In particular, we demonstrate that the form of the supercurrent–magnetic field relation as the fractal generation number increases can be directly related to the self-similar fractal geometry of the normal metallic layer. Furthermore, the maxima of the corresponding diffraction pattern directly encode the self-repeating fractal structure in the course of fractal generation, implying that the corresponding magnetic length directly probes the shortest length scale in the given fractal generation. Our results should motivate future experimental efforts to verify these predictions in designer quantum materials and motivate future pursuits regarding fractal-based SQUID devices.

Evaluation of selection strategies in dual-purpose and specialized breeding of indigenous chicken

This study aimed to evaluate various selection strategies for adoption in dual-purpose (ICD), meat (ICM) and layer (ICL) breeding goals in indigenous chicken breeding programs. The ICM goal aimed to improve live weight (LW12), daily gain (ADG) and egg weight (EW12) or together with feed efficiency and antibody response. For the ICL goal, age at first egg (AFE) and egg number (EN12) or together with feed efficiency and antibody response were targeted. In the ICD goal, the objective was to improve LW12, ADG, AFE and EN12 or together with feed efficiency and antibody response. Highest total index responses of US$ 49.83, US$ 65.71, and US$ 37.90 were estimated in indices targeting only production traits in the ICD, ICM and ICL goals, respectively. Highest index accuracy estimates of 0.77 and 0.70 were observed in indices that considered production and feed-related traits in the ICD and ICL goals, respectively, while in the ICM goal, the highest estimate of 0.96 was observed in an index targeting only production traits. Inbreeding levels ranged from 0.60 to 1.14% across the various indices considered in the breeding goals. Targeting only production traits in the ICD, ICM and ICL goals required the least number of generations of selection of 7.46, 5.50, and 8.52, respectively, to achieve predefined gains. Generally, a strategy targeting only production traits in a goal was the most optimal but resulted to unfavorable correlated responses in feed efficiency and antibody response. Addition of feed efficiency or/and antibody response in a goal was, however, not attractive due to the decline in total index response and accuracy and increase in inbreeding levels and number of generations of selection. Considering the feed availability and disease challenges in the tropics, choice of including feed efficiency or/and antibody response in the ICD, ICM and ICL goals should depend on targeted production system, resource availability to support breeding activities and magnitude of correlated responses on these traits when not included in the goals.

Bioconvective peristaltic transport of hydromagnetic Sutterby nanofluid through a chemically activated porous channel with gyrotactic microorganisms

The main target of this article is to analyze the role of activation energy and thermal radiation effects on the bioconvective peristaltic transport of Sutterby nanofluid in a two-dimensional flexible porous channel with heat and mass transfer. Also, the consequences of Hall current, heat source, and complaint wall properties along with an inclined magnetic field are taken into consideration. The proposed system of governing equations is simplified by using lubrication approximation and solved numerically using MATLAB's bvp5c solver. Further, numerical observations are analyzed to figure out the consequence of different physical parameters on the flow characteristics. According to the observations, it is identified that the Sutterby nanofluid velocity declines with the climb in the damping force parameter, while it enhances with the upsurge in the Darcy number. The Sutterby fluid temperature profile strengthens when the influence of the heat generation and Brinkman number increase, while it depicts the reverse effect with the elevation in the fluid parameter and radiation parameter. The temperature ratio and activation energy parameters were found to have a significant impact on the fluid concentration. The volume of the trapped fluid bolus is an enhancing function of the channel's non-uniformity parameter. Moreover, current work reveals its applicability to recognize the hemodynamic flow analysis and other biofluid movements in the human body and industrial sectors.

Thermal distribution analysis of rectangular fin considering multiboiling heat transfer modes

AbstractIn this investigation, a numerical method is used to compute the thermal distribution analysis of a rectangular fin with surface emissivity and internal heat generation. Here, the thermal conductivity, heat generation, emissivity at the surface, and coefficient of heat transfer depend on temperature linearly. The role of four distinct multiboiling heat transfer modes such as laminar film boiling (condensation), laminar convection, turbulent convection, and nucleate boiling are discussed in detail and the corresponding outcomes are displayed graphically. Isolated (insulated) and convective tip boundary conditions for the fin tip are employed in this study. The solution is obtained using shooting technique involving Runge Kutta Fehlberg method. It is emphasized that the thermal distribution shows a diminishing trend for the convective tip condition compared to the insulated tip. In addition to this, it is illustrated that laminar film boiling and laminar convection are two effective modes of heat transfer in comparison with turbulent convection and nucleate boiling for a finned surface in boiling liquids. The study on fin efficiency shows that fin efficiency increases with the increase in internal heat generation number.

Nanoparticle transport and deposition in a heterogeneous human lung airway tree: An efficient one path model for CFD simulations

Understanding nano-particle inhalation in human lung airways helps targeted drug delivery for treating lung diseases. A wide range of numerical models have been developed to analyse nano-particle transport and deposition (TD) in different parts of airways. However, a precise understanding of nano-particle TD in large-scale airways is still unavailable in the literature. This study developed an efficient one-path numerical model for simulating nano-particle TD in large-scale lung airway models. This first-ever one-path numerical approach simulates airflow and nano-particle TD in generations 0–11 of the human lung, accounting for 93% of the whole airway length. The one-path model enables the simulation of particle TD in many generations of airways with an affordable time. The particle TD of 5 nm, 10 nm and 20 nm particles is simulated at inhalation flow rates for two different physical activities: resting and moderate activity. It is found that particle deposition efficiency of 5 nm particles is 28.94% higher than 20 nm particles because of the higher dispersion capacity. It is further proved that the diffusion mechanism dominates the particle TD in generations 0–11. The deposition efficiency decreases with the increase of generation number irrespective of the flow rate and particle size. The effects of the particle size and flow rate on the escaping rate of each generation are opposite to the corresponding effects on the deposition rate. The quantified deposition and escaping rates at generations 0–11 provide valuable guidelines for drug delivery in human lungs.

Polymeric photonic quasicrystal: octonacci sequence and elasto-optic effect

Here we would like to discuss the light transmission modulation by the one-dimensional polymeric quasi-multilayer which is formed according to substitutional generalized Octonacci with PMMA and PS as the constituent materials. In particular, we will present some theoretical findings using the well-known transfer matrix method. The width of the PBG, the inter-band spacing and the depth of the PBGs can be managed by choosing the appropriate generation number, whereas the number of the major PBGs is the same for all the considered generation numbers. Regarding the position of the PBGs, we found that, with an increase in generation number, the aroused PBGs are shifted symmetrically towards the designed frequency. It also reveals the aroused forbidden frequency band can be manipulated by changing the applied hydrostatic pressure. With an increase in pressure, the frequency spectra are shifted to a higher frequency. In addition to this, we also found that as the thickness of the polymers increases the PBGs are red-shifted. The proposed structure could be another possible system for optical device design specially multi-band tunable optical reflectors.

Great granny still ruling from the grave: Phenotypical response of plant performance and seed functional traits to salt stress affects multiple generations of a halophyte

Abstract Environmental changes, for example, in rainfall and land use, lead to changes in the environment experienced by subsequent generations of plant species. Environmental conditions of maternal plants can influence the fitness and phenotypes of subsequent generations via non‐genetic mechanisms: transgenerational plasticity (TGP). However, relevant empirical evidence remains scarce and ambiguous. What are the adaptive consequences of TGP for plants in the face of environmental change? For how many generations does the TGP effect remain? We tried to answer these questions by measuring life‐history traits and reproductive characteristics of progeny plants of the diaspore‐heteromorphic annual halophyte Atriplex centralasiatica in a 3‐year TGP experiment covering F0, F1 and F2 and partly F3. Plants from diaspore types A (low dispersal and high germination ability) and C (high dispersal and low germination ability) were grown in favourable versus stressful salinities over three generations in a fully factorial design. Transgenerational plasticity of plants grown in favourable versus stressful salinities decreased from F2 → F1 → F0. Compared to the favourable condition, the stressful condition decreased the length of the vegetative period, increased the length of reproductive time, reproductive allocation and progeny diaspore size. Salinity tolerance and phenotypic plasticity were higher in plants from diaspore A than in those from diaspore C. In the stressful condition, plants produced less plant biomass, larger diaspores, a higher proportion of diaspore C, but lower proportion of diaspore A. Production of the proportion of diaspore C increased with increase in number of previous generations that experienced stress. The stress experience of the great‐great grandmother (F0) continued into the lower A:C ratio of the F3 diaspores. Synthesis. Our findings provide evidence for the ‘escape strategy’ of A. centralasiatica: TGP could spread the risk of environmental adversity by delaying seed germination temporally and broadening seed dispersal spatially, thus allowing plants to cope with environmental heterogeneity. Specifically, the trade‐off in reproductive allocation between diaspores A and C enables plants to develop divergent strategies. New research should reveal the extent to which wide‐ranging taxa can benefit from TGP and whether even (great)‐great grandmother might be the starting point of TGP.

Response to four generations of selection for growth performance traits in mandarin fish (Siniperca chuatsi)

Selective breeding refers to the selection of individuals or populations with superior genetic traits from a population or family, for the purpose of directionally screening and enriching the dominant traits of the target species, to acquire breeds with directional dominant traits. The mandarin fish (Siniperca chuatsi) is an important high-quality freshwater fish widely cultured in China. The selective breeding of this species to obtain desirable growth performance traits has garnered considerable attention by researchers. We constructed a basic breeding population by selecting high growth as the target trait. Subsequently, we conducted family selection through four successive generations. We used the growth data (initial and harvest body weights) of the four generations of mandarin fish to estimate the realized heritability, selection response, and genetic gain, on the body weight of mandarin fish. We obtained the following values from generations F1–F4: realized heritability 0.17–0.47, selection response 0.40–1.12, and genetic gain 6.94–17.25%. The average genetic gain was 12.14%. Moreover, after four generations of breeding, the average growth rate of the selective breeding population had increased by 16.3% compared with that of the control group. This indicated that selective breeding had resulted in good genetic progress regarding the growth traits of mandarin fish and desirable selection effects. The coefficient of variation for the harvest body weight of generations F1–F4 decreased with increasing generation number (18.68–10.10%). This shows that the degree of variation in body weight among families decreased over generations, tending towards genetic stability after selective breeding. Our results provide a scientific basis and technical support for mandarin fish breeding and may serve as a reference for breeding other aquaculture species.

Differential impact of a dyskeratosis congenita mutation in TPP1 on mouse hematopoiesis and germline.

Telomerase extends chromosome ends in somatic and germline stem cells to ensure continued proliferation. Mutations in genes critical for telomerase function result in telomeropathies such as dyskeratosis congenita, frequently resulting in spontaneous bone marrow failure. A dyskeratosis congenita mutation in TPP1 (K170∆) that specifically compromises telomerase recruitment to telomeres is a valuable tool to evaluate telomerase-dependent telomere length maintenance in mice. We used CRISPR-Cas9 to generate a mouse knocked in for the equivalent of the TPP1 K170∆ mutation (TPP1 K82∆) and investigated both its hematopoietic and germline compartments in unprecedented detail. TPP1 K82∆ caused progressive telomere erosion with increasing generation number but did not induce steady-state hematopoietic defects. Strikingly, K82∆ caused mouse infertility, consistent with gross morphological defects in the testis and sperm, the appearance of dysfunctional seminiferous tubules, and a decrease in germ cells. Intriguingly, both TPP1 K82∆ mice and previously characterized telomerase knockout mice show no spontaneous bone marrow failure but rather succumb to infertility at steady-state. We speculate that telomere length maintenance contributes differently to the evolutionary fitness of humans and mice.

A model for calculating beta exposure doses to tracheobronchial cells during movement of a point source

The article describes a model and method for calculating beta-exposure doses to secretory and basal cells of the tracheobronchial part of the respiratory tract when a point source of 1 Bq activity moves along the inner surface of respiratory formations. The calculations, that used for proposed model, were performed by using a 90Y point source as an example. The dose calculation model takes into account the speed o f movement of the radiation source in each respiratory formation, the size of the respiratory formations, and the depth of the secretory and basal cells. The dose calculation is based on the dose rate attenuation functions published by W. G. Cross et al. (DOI: 10.1097/00004032-199208000-00002). The calculations were performed for a cylindrical model of a respiratory formation. Two kinds of cells were considered for the dose estimation: cells irradiated without beta-particle exit into bronchial lumen (type 1 cells) and cells irradiated due to beta-par­ticle exit into bronchial lumen (type 2 cells). The results of calculations showed, that as far as the generation number increasing, the average irradiation doses of the type 1 cells are 10 or more times greater than those of the type 2 cells. With increasing generation number in the tracheobronchial tree, doses per cells increase by several orders of magnitude. The highest doses are formed in bronchioles of generations 9-15, reaching units and tens of mGy. In spite of the fact that the number of generation increases, the total number of irradiated cells decreases, the collective doses of irradiated cells (sum of doses to all cells of the respiratory formation) in the last generations are 30-50 times higher than the doses of the first generations. Thus, in case of a single point source, there is a significant (by many orders of magnitude) scatter of doses to individual cells in indi­vidual respiratory formation, as well as significant differences in average doses of trachea, individual bronchi and bronchioles.

Entropy optimization and heat transfer analysis in MHD Williamson nanofluid flow over a vertical Riga plate with nonlinear thermal radiation

The entropy generation for a reactive Williamson nanofluid flow past a vertical Riga system is the subject of this article. The effects of MHD, thermophoresis, nonlinear heat radiation and varying heat conductivity are modeled into the heat equation in the established model. Suitable similarity transformations are examined to bring down the partial differential equations into ordinary differential equations. The Homotopy analysis approach is used to solve the dimensionless transport equations analytically. The graphic information of the various parameters that emerged from the model is effectively collected and deliberated. The temperature field expands with thermophoresis, Brownian motion and temperature ratio parameters as the modified Hartmann number forces an increase in velocity, according to the findings of this analysis. With the increase in the fluid material terms, the entropy generation and Bejan number increase. Riga plate has numerous applications in improving the thermo-physics features of a fluid, the value of magnetic field embraces an important role in fluid mechanics. An external electric field can be used to control flow in weak electrically conductive fluids. The Riga plate is one of the devices used in this regard. It’s a device that creates electromagnetic fields. They produce the Lorentz force which is a force that directs fluid flow. The authors have discussed the entropy optimization for a reactive Williamson nanofluid flow past a vertical Riga plate is addressed. This is the first investigation on mass and heat transfer flow that the authors are aware of, and no similar work has yet been published in the literature. A thorough mathematical examination is also required to demonstrate the model’s regularity. The authors believe that the results acquired are novel and have not been plagiarized from any other sources.

Performance evaluation and entropy generation of chevron-type plate-fin equipped with ribs and holes

The complexity caused by an enhanced technique may significantly enhance the heat transfer along with a penalty in the pressure drop. Thus, it is needed to assess the counteracting effects between the enhanced heat transfer and the augmented pressure drop in practical applications. In order to comprehensively evaluate the hydrothermal performance of the chevron-type plate-fin (CTPF) equipped with ribs and holes, this study focuses on the relationship between hydraulic and thermal characteristics. Firstly, the relationship between the Colburn factor and the friction factor is presented, then two performance indexes are applied using these factors to evaluate the use of ribs and holes in the CTPIt F is found that the simultaneous use of ribs and holes shows better overall performances as compared with the use of ribs or holes individually. At the same geometrical parameters, the highest values of 1.52 and 1.07 are recorded for these performance indexes. In order to further improve the overall performance of the CTPF, the effects of geometrical parameters are also investigated. With the decrease of corrugation amplitude ( a) and the increase of corrugation length ( l), rib height ( h), and rib thickness ( t), the CTPF performs better overall performances. And, for the models with different levels of hole width ( w), the better performance is seen when this parameter is at the middle level. However, in the studied models, the best overall hydrothermal performance is detected for the model with a = 2.5 mm, l = 60 mm, h = 2.5 mm, t = 10 mm, and w = 10 mm, and highest performance indexes of 2.52 and 1.15 are reported for this model. Likewise, an entropy generation analysis is carried out, and the obtained results are discussed based on the Bejan number and entropy generation number. The results show that the increase of Reynolds number can lead to decrease of Bejan number and to increase of entropy generation number. For Reynolds number ranging from 4000 to 10000, the best model, which is described above, shows 17% decrease in the entropy generation number comparing with the reference model. Finally, two correlations are developed to predict the Bejan number and entropy generation number of the current study.

Pest scenario of Spodoptera litura (Fab.) on groundnut under representative concentration pathways (RCPs) based climate change scenarios.

Multi-model ensemble of Maximum (Tmax) and Minimum (Tmin) temperature data of four Representative Concentration Pathways viz., RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5 of Coupled Model Intercomparison Project 5 (CMIP5) models were generated for ten major groundnut growing locations of the India to predict the number of generations of Spodoptera litura (Fab.) using Growing Degree Days approach during three future climate viz., Near (NF), Distant (DF) and Very Distant (VDF) periods and were compared over 1976-2005 baseline period (BL). Projections indicate significant increase in Tmax (0.7-4.7°C) and Tmin (0.7-5.1°C) in NF, DF and VDF periods under the four RCP scenarios at the ten groundnut growing locations. Higher percent increase of the number of generations of S. litura was predicted to occur in VDF (6-38%) over baseline, followed by DF (5-22%) and NF (4-9%) periods with reduction of generation time (5-26%) across the four RCP scenarios. Reduction of crop duration was higher (12-22 days) in long duration groundnut than in medium and short duration groundnut. Decrease in crop duration was higher in VDF (12.1-20.8 days) than DF (8.26-13.15 days) and NF (4.46-6.15 days) climate change periods under RCP 8.5 scenario. Increase in number of generations of S. litura was predicted even with altered crop duration of groundnut. Among locations, more number of generations of S. litura with reduced generation time are likely at Vridhachalam and Tirupathi locations. Geographical location (74-77%) and climate period (15-19%), together explained over 90 percent of the total variation in the number of generations and generation time of S. litura. These findings suggest that the incidence of S. litura on groundnut could be higher in future.

Dodecanacci superconductor-metamaterial photonic quasicrystal

This paper presents the numerical study of Dodecanacci superconductor-metamaterial based one-dimensional quasiperiodic multilayer to determine their critical transmittance properties of photonic spectra using transfer matrix simulations. Initially, the transmission characteristics for Dodecanacci quasicrystal were examined along with various parametric effects including the thickness of building blocks and operating temperature for different generations of Dodecanacci quasiperiodic sequence. A vast number of distinct forbidden bandgaps and transmission peaks was observed until a few generations (≤3). Interestingly, the forbidden bandgaps were becoming wider, in other words, the transmission bands become narrower with an increase in generation number. However, there is a distinct red and blue shift was observed in the spectra with an increase in temperature and an increase in quasicrystal layer thickness respectively. Hence this study strongly supports that the Dodecanacci superconductor-metamaterial based one-dimensional quasiperiodic multilayered structures could be potentially used for applications like tunable optical reflectors or tunable narrowband filters based on its generation number and operating conditions.

Effect of generation number on properties of fluoroalkyl‐terminated hyperbranched polyurethane latexs and its films

AbstractThe 1–3 generations of hyperbranched polyesters (HBPE‐1/2/3) were synthesized from trimethylolpropane (TMP) and 2,2‐dimethylol propionic acid (DMPA) by “quasi‐one‐step method.” Then, isophorone diisocyanate (IPDI), polybutylene adipate (CMA‐1044), DMPA and 1,4‐butanediol (BDO) were utilized to prepare the urethane prepolymer (PU), which was reacted with HBPE to synthesize hyperbranched polyurethanes (HBPU). Finally, 1–3 generations of fluoroalkyl‐end‐capped hyperbranched polyurethanes (FHBPU) latexes were obtained by the reaction of perfluorohexyl ethanol (S104) and HBPU as well as the self‐emulsification process. Structure of the products, the properties of different FHBPU emulsions and its films were investigated by FTIR, 1H NMR, TEM, DLS, TGA, XPS, XRD, SEM, AFM and static contact angle measuring instrument. Results showed that the particle size of FHBPU latexes increased gradually with the increase of generation number. SEM and XRD results verified that an amount of the crystal particles was increased with the increase of generation number. XPS and AFM demonstrated that degree of microphase separation and film roughness was increased with the increase of branching degree. Static water contact angles could attain 95.9°, 100.3°, and 107.0°, respectively on the 1–3 generations of FHBPU films, compared to that on PU (75.1°).

Dodecanacci extrinsic magnetized plasma multilayer

An extrinsic magnetized plasma quasi-multilayer is demonstrated using the transfer-matrix method with an extrinsic bulk plasma inspired structure. The transmittance of the extrinsic bulk plasma quasi-system has been shown using the Dodecanacci quasi-sequence. For the periodic structure, two significant gaps emerge and only one of them, the bandgap above the plasma frequency, appears in any of the proposed Dodecanacci systems and it is magnetically tunable and robust against the position of the layers. The other bandgap, observed below the plasma frequency is also magnetically tunable but it vanishes when the layers are quasiperiodically disposed because the emergence of several resonant peaks. The count and width of the transmission window in such vanished bandgaps decrease as the Dodecanacci generation number increases. The results also show that the electron density can control the gap location and gap width for all Dodecanacci structures. These listed results ensure that the approach of Dodecanacci extrinsic magnetized plasma multilayers can be applied to the design of future architectures for the control and the manipulation of the electromagnetic wave-matter interaction in microwave frequencies.

Magnetohydrodynamic natural convection and entropy generation analyses inside a nanofluid-filled incinerator-shaped porous cavity with wavy heater block

The aim of the current study is natural convection analysis conjugated with entropy generation analysis in an incinerator shaped permeable enclosure loaded with Al2O3–H2O nanofluid subjected to the magnetic field with a rectangular wavy heater block positioned on the bottom of the cavity wall. The bottom and top horizontal walls are adiabatic; the inclined and vertical walls are thought to be cooled. Firstly, the governing expressions and standard k–e turbulence model are rewritten from dimensional form to non-dimensional form using dimensionless parameters such as vorticity and stream function. In the next step, the equation of entropy generation is written in dimensionless form. Then, the system of non-dimensional governing equations is solved by the finite volume method (FVM) conjugated with a non-dimensionalization scheme using ANSYS Fluent. Fine grids (wall y+ < 2) with inflated layers have been used for the higher Rayleigh number. The effects of the Rayleigh number in the laminar region (Ra = 103, 104, and 105) and turbulent region (Ra = 108, 0.5 × 109, and 109), Darcy number (Da = 0.01 and 100), Hartmann number (Ha = 0 and 40), and the nanoparticles ( $$ \phi = 2{{\% }} $$ ) on the entropy generation number and natural convection are investigated. The validation results were in good agreement with those of the literature. The results demonstrate that for the laminar region, the Nusselt number and entropy generation number increase as the Rayleigh number and the Darcy number grow, whereas both of them abate as Hartmann number increases. In the turbulent region, the average Nusselt number decreases by ascending the Darcy number. Also, for turbulent region (Ra = 109), convection flow strength decreases 6.28% when Hartmann number increases from 0 to 40, whereas the entropy generation number increases 31.5% at Da = 0.01.

Climate change alters elevational phenology patterns of the European spruce bark beetle (Ips typographus).

The European spruce bark beetle Ips typographus is the most important insect pest in Central European forests. Under climate change, its phenology is presumed to be changing and mass infestations becoming more likely. While several studies have investigated climate effects across a latitudinal gradient, it remains an open question how phenology will change depending on elevation and topology. Knowing how an altered climate is likely to affect bark beetle populations, particularly across diverse topographies and elevations, is essential for adaptive management. We developed a time-varying distributed delay model to predict the phenology of I. typographus. This approach has the particular advantage of capturing the variability within populations and thus representing its stage structure at any time. The model is applied for three regional climate change scenarios, A1B, A2 and RCP3PD, to the diverse topography of Switzerland, covering a large range of elevations, aspects and slopes. We found a strong negative relationship between voltinism and elevation. Under climate change, the model predicts an increasing number of generations over the whole elevational gradient, which will be more pronounced at low elevations. In contrast, the pre-shift in spring swarming is expected to be greater at higher elevations. In comparison, the general trend of faster beetle development on steep southern slopes is only of minor importance. Overall, the maximum elevation allowing a complete yearly generation will move upwards. Generally, the predicted increase in number of generations, earlier spring swarming, more aggregated swarming, together with a projected increase in drought and storm events, will result in a higher risk of mass infestations. This will increase the pressure on spruce stands particularly in the lowlands and require intensified management efforts. It calls for adapted long-term silvicultural strategies to mitigate the loss of ecosystem services such as timber production protection against rockfall and avalanches and carbon storage.

Effect of magnetic field on mixed convection and entropy generation of hybrid nanofluid in an inclined enclosure: Sensitivity analysis and optimization

In this paper, a numerical study has been examined on the effect of the presence of a magnetic field on the rate of convective heat transfer and entropy generation of a hybrid nanofluid (water/Al2O3-CuO (50/50)) in a square diagonal cavity. The horizontal walls of the insulating cavity and fixed temperature source are set on the left and right vertical wall with cold temperature. The governing equations are solved by finite volume method using the SIMPLE algorithm. In this paper, the effect of the Richardson number, Hartman number, thermal source length on hybrid entropy generation and convective heat transfer rate has been examined. Using the Response Surface Methodology (RSM) method, a polynomial equation is obtained between the three parameters given for the Nusselt number, total entropy generation and Bejan number. Then the sensitivity of responses to factors is checked. Finally, depending on the importance of each of the responses, we use the optimal points where simultaneously the highest Nu number, the lowest entropy generation, and Bejan number occur. The results show that with increasing Richardson number, heat transfer rate is reduced, and this reduction is more pronounced in smaller Hartmann number. Also, total entropy generation increased with increasing Richardson number, but Bejan number reduced. With increasing the intensity of the magnetic field and reducing the length of the thermal source, the heat transfer rate also reduces. However, with increasing the intensity of the magnetic field, the total entropy generation and Bejan number increase. Also, with increasing the length of the thermal source, the total entropy generation and Bejan number increase.

Numerical analysis of entropy generation of a nanofluid in a semi-annulus porous enclosure with different nanoparticle shapes in the presence of a magnetic field

One of the important problems in the field of heat transfer is the investigation of natural convection heat transfer in cavities. The next step is the study of entropy generation. The object of the present work is the investigation of the entropy generation in a semi-annulus porous cavity filled with Cu-water nanofluid in the presence of a magnetic field. The outer and inner semi-circular walls are kept at constant temperatures whereas the two other walls are insulated. Firstly, the governing equations (i.e. continuity, momentum and energy equations) are numerically solved by the Control Volume based Finite Element Method (CVFEM) and then the entropy generation number is calculated. The effects of the Rayleigh number, Darcy number, Hartmann number, angle of magnetic field, the nanoparticle volume fraction, the particle shape and the angle of turn for the enclosure, number and amplitude of undulation in the wavy wall on the entropy generation number are investigated. Also, a new criterion for the evaluation of cavity thermal performance is defined that is called ECOP. The results were compared with those of the literature and good agreement was observed. The results show that the Nusselt number and entropy generation number increase as the Rayleigh number and the nanoparticle volume fraction increase. Also, the entropy generation number decreases with increasing the Hartmann number whereas it increases as the Darcy number increases.