The post-dynamic recrystallization behavior of ultrafine-grained (UFG: 0.44
μ
m) cp-Ti under annealing, room temperature (RT) monotonic and cyclic loading was investigated across a range of ...temperatures and deformation rates wherever appropriate. By characterizing the grain and boundary structures, it was confirmed that recrystallization and grain growth occurred due to annealing (≥ 600 °C) and
R
= − 1 fatigue at RT. There was a noticeable 30 deg aggregation in misorientation distribution, along with the increased grain size. However, the hypothetical correlation between 30 deg aggregation and Σ13a or the other characteristic coincidence site lattice boundaries was found to be weak. The fatigue-induced grain growth is particularly intriguing for two reasons. First, the large monotonic deformation with low strain rate cannot trigger grain growth. Second, fatigue sharpened the basal intensity around the ND and caused a weaker texture component close to TD (load axis along the LD, perpendicular to the TD–ND plane). By contrast, high-temperature annealing only strengthened the UFG processing induced basal pole but without affecting its location. Novel insights into this fatigue-induced texture evolution in UFG cp-Ti has been provided. The lattice rotation during fatigue can be attributed to the combined effect of activation of prismatic
⟨
a
⟩
slip parallel to LD, and basal
⟨
a
⟩
slip perpendicular to it. The theoretically calculated stress to activate dislocation slip by assuming a non-equilibrium grain boundary state lent support to the above assertion. Moreover, the TEM observation evidently showed the characteristics of dislocation cross-slip and multiple slip in the grain interior.
Graphical Abstract
The Oriental Fruit Moth Grapholita molesta (Busck) causes substantial damage to stone and pome fruit crops worldwide. Light-based traps offer a potential means for pest monitoring and management. In ...this study, we tested the preference of G. molesta for the following light sources: monochromatic light produced from light-emitting diodes (LEDs) (red, orange, yellow, green, blue, violet, and white), specific wavelengths of light produced from filters (405, 450, 480, 512, 540, 576, and 610 nm), and polychromatic light produced by different numbers (0, 12, 24, and 36) of green, blue, and violet LEDs. The arrangement of polychromatic lights was based on an orthogonal design matrix of L16 (43). Based on the results of former studies, we further determined the optimal number of green and violet LEDs. The results showed that: 1) G. molesta strongly preferred the green, violet, and blue LEDs; 2) G. molesta significantly preferred light at 405 nm, followed by 540 nm, and showed no phototaxis to 480 nm; 3) for the polychromatic light configuration, violet and green were the factors that determined the preference of G. molesta, and the lamp with 12 violet LEDs captured the most moths; and 4) for the lamps with different light intensities, 36 violet LEDs or 12 green LEDs attracted the most moths, with the former performing better.
Aims
Cardiovascular disease (CVD) is now the most prevalent and debilitating disease affecting the Chinese population. The goal of the present manuscript was to analyse cardiovascular risk factors ...and the prevalence of non-fatal CVDs from data gathered from the 2007-2008 China National Diabetes and Metabolic Disorders Study.
Methods and results
A nationally representative sample of 46 239 adults, 20 years of age or older, was randomly recruited using a multistage stratified design method. Lifestyle factors, diagnosis of CVD, stroke, diabetes, and family history of each subject were collected, and an oral glucose tolerance test or a standard meal test was performed. Various non-fatal CVDs were reported by the subjects. SUDAAN software was used to perform all weighted statistical analyses, with P < 0.05 considered statistically significant. The prevalence of coronary heart disease, stroke, and CVDs was 0.74, 1.07, and 1.78% in males; and 0.51, 0.60, and 1.10% in females, respectively. The presence of CVDs increased with age in both males and females. The prevalence of being overweight or obese, hypertension, dyslipidaemia, or hyperglycaemia was 36.67, 30.09, 67.43, and 26.69% in males; and 29.77, 24.79, 63.98, and 23.62% in females, respectively. In the total sample of 46 239 patients, the prevalence of one subject having 1, 2, 3, or ≥4 of the 5 defined risk factors (i.e. smoking, overweight or obese, hypertension, dyslipidaemia, or hyperglycaemia) was 31.17, 27.38, 17.76, and 10.19%, respectively. Following adjustment for gender and age, the odds ratio of CVDs for those who had 1, 2, 3, or ≥4 risk factors was 2.36, 4.24, 4.88, and 7.22, respectively, when compared with patients with no risk factors.
Conclusion
Morbidity attributed to the five defined cardiovascular risk factors was high in the Chinese population, with multiple risk factors present in the same individual. Therefore, reasonable prevention strategies should be designed to attenuate the rapid rise in cardiovascular morbidity.
► The heat transfer rate can be enhanced by porous materials by 2.5 times in the solid region. ► The natural convection is weakened by the porous structures. ► Two heating methods are investigated to ...examine the natural convection effect. ► The issue of corrosion process is briefly discussed.
In this paper, the feasibility of using porous materials such as metal foams and expanded graphite to enhance the heat transfer capability of PCMs in high temperature thermal energy storage system is experimentally investigated. Experimental results showed that the heat transfer rate can be enhanced through addition of the porous materials by 2.5
times compared to that of pure NaNO
3 in the heating process from 250–300
°C. However the heat transfer rate could be reduced by half in the liquid region since the natural convection can be severely suppressed by the porous structures. In an attempt to further reveal the natural convection effect in PCMs embedded in porous materials, two heating methods (boundary conditions) are examined. Finally the issue of corrosion process is briefly discussed.
The current study investigated the saturated pool boiling heat transfer of deionized water with added surfactant on a horizontal metallic foam surface with V-shape grooves under atmospheric pressure. ...The influences of the groove configurations, sodium dodecyl sulfate (SDS) concentration, foam thickness, and thermal conductivity of foam material on heat transfer performance and bubble growth patterns were studied. SDS with concentrations of 100, 400, and 800
ppm was used as the surfactant. The foam porosity was fixed at 0.95. V-shape grooves with various widths and groove number were manufactured in the foam samples, with three pore densities of 20, 100, and 130
PPI. Results showed that the effects of the groove configuration, SDS concentration, and thickness on boiling heat transfer are heavily dependent on foam pore density. The counter-flow between the released bubbles and sucked liquid plays a significant role in heat transfer performance. The existence of sufficient grooves delays the critical heat flux (CHF), whereas SDS can achieve CHF earlier.
Compared with single-stage latent heat storage, cascaded latent heat storage is considered as an effective way to store and utilize intermittent or fluctuant thermal energy due to an increased heat ...transfer rate, a uniform and lower HTF outlet temperature, faster charging/discharging processes and higher exergy efficiency. In this paper, an experimental three-stage latent heat storage system filled with three different phase change materials is established and its heat charging process is studied. Its temperature evolution in each stage during the heat charging process is measured and the corresponding thermodynamic performance is analyzed. Besides, the effects of stage number, HTF inlet temperature and HTF flow rates on the thermodynamic performance are discussed, respectively. The results show that the solid-liquid phase change in the three stages does not take place simultaneously due to the poor heat transfer and the large melting temperature difference. In addition, more stages could improve energy storage efficiency, exergy storage efficiency and entransy storage efficiency. Higher HTF inlet temperatures and larger HTF flow rates could increase transfer and storage rates of energy, exergy and entransy, but the storage efficiency of energy, exergy and entransy could only be obviously improved by higher HTF inlet temperatures.
•An experimental three-stage latent heat storage system is established.•The temperature evolution inside the storage unit is measured and investigated.•The thermodynamic performance analysis of the experimental system is carried out.•The effects of stage number, inlet temperatures and flow rates are studied.
► Boiling was governed by bubble escaping resistance, surface area, capillary force. ► Optimal groove volume ratio was 7.76% and 5.84% at 100 and 130PPI pore density. ► Optimal groove width was 2mm ...at the three groove number values (1, 2, and 3).
Pool boiling heat transfer on horizontal metallic foam surface with crossing and single-directional V-shaped groove was experimentally investigated at atmospheric pressure using deionized saturated water as the working liquid. Boiling patterns were captured using a high speed camera. The porosity of studied copper foam was fixed as 0.95. Thirty test samples categorized into three groups were studied. The influences of crossing V-shaped groove array configuration, single-directional groove width, and number on the heat transfer performance were examined respectively for the three groups in turn. The boiling process was governed by combinational interaction of three major factors of bubble escaping resistance, heat transfer surface area, and capillary force. The exhibited heat transfer performance of the metallic foam depended on whichever of the above factors dominated the boiling progress. Almost all V-shaped grooves could enhance the pool boiling heat transfer compared with foam surface without grooves. The optimal groove array configuration corresponding to highest heat transfer coefficient was connected to its groove volume ratio which was the very transition point for the behavior of the dominant factor. The optimal volume ratio for crossing groove array was 7.76% at pore density of 100PPI and 5.84% at pore density of 130PPI. The effect of groove number was heavily dependent on foam thickness. The optimal groove width of 2mm was found for the three groove number values (1, 2, and 3). The boiling characteristics were illustrated with boiling patterns obtained from the high speed camera. The present study could aid enhanced boiling surface design of sintered porous surface.
•Pool boiling heat transfer of gradient metal foams was investigated experimentally.•The main influencing factors are layer number and foam material gradient.•Departure bubble becomes smaller when it ...is colliding with the nickel foam skeleton.•Surfactant effect is dependent on concentrations and nanoparticle deposition condition.
Pool boiling heat transfer of gradient metal foams has been investigated in saturated pure deionized water and surfactant solutions at atmospheric pressure. Pore density gradients are from 5 PPI to 100 PPI, while the porosity remains at the fixed value of 0.98. The parametric study is performed by varying foam layer number and material. Alumina nanoparticle and surfactant (SDS and Triton X-100) effects on pool boiling heat transfer of gradient metal foams are also investigated. Images of nanoparticle-deposited foam fiber are captured by SEM. Bubble growth inside the gradient metal foams is captured by a high-speed camera. For no-nanoparticle-deposited gradient metal foams, pool boiling heat transfer in deionized water is heavily dependent on foam layer number and material gradient. For nanoparticle-deposited gradient metal foams, pool boiling heat transfer in surfactant solutions is dependent on surfactant concentrations and nanoparticle deposition condition on the metal skeletons. The visualization results show that departure bubble size first increases and then decreases in the gradient copper–nickel foam.
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