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排序方式: 共有381条查询结果,搜索用时 93 毫秒
51.
A unified dynamic theory for polarizable and magnetizable magneto-electro thermoviscoelastic. electrically and thermally conducting anisotropic solids possessing magnetic symmetry is developed for time-dependent electromagnetic fields. Considering the Chu formulation of the Maxwell equations, the balance equations of nonrelativistic continuum mechanics and the boundary conditions together with the constitutive equations for anisotropic materials are given. It is shown that the entropy, polarization. magnetization and the nondissipative part of stress are derivable from a potential while the dissipative part of stress, electric current and heat flux vectors satisfy a residual inequality. The theory developed for a general anisotropy and interaction is applied to special cases. 相似文献
52.
Banu Barutça Levent Köroğlu Erhan Ayas A. Tansu Koparal 《Ceramics International》2018,44(7):8094-8099
The cytotoxicity of monticellite based bioactive ceramic powder, which was synthesized from boron derivative waste has been determined by in vitro assays of MTT, NRU, and JC-1 staining. The toxicity of powder on different mammalian cell lines (3T3-L1, HUVEC, CRL-2120) was evaluated at the concentrations of 10, 100, 200, 400 and 800?µg/mL to justify its potential for biomedical applications. The obtained results showed that monticellite based bioactive ceramic powder possesses not only bioactive feature but also biocompatible characteristic at the concentration range of 10–200?µg/mL. Hence, monticellite based bioactive ceramics have high potential as a bone graft substitute for bone void filling and coating applications. 相似文献
53.
Özgür Sevgi Canarslan Levent Koroglu Erhan Ayas Necip Suat Canarslan Alpagut Kara Paolo Veronesi 《Ceramics International》2021,47(1):828-835
In the present study, 17 wt % TiN reinforced α-β SiAlON composites were sintered at low temperature by susceptor-assisted microwave heating. The effect of TiN addition on dielectrical properties of starting powders, as well as the influence of sintering temperature on phase evolution, microstructure development and mechanical properties of α/β-SiAlON-TiN composites were investigated. The obtained results showed that TiN addition increased the microwave absorbing properties which is reflected in the peak sintering temperature. Thus, the α:β ratio decreased and mechanical properties were improved, especially the fracture toughness of the composites. Furthermore, an estimate of energy consumption during microwave assisted sintering at the laboratory scale is presented. As a result, the highest values for relative density (97.1%), Vickers hardness (13.35 ± 0.47 GPa), and fracture toughness (7.52 ± 0.54 MPa m1/2) were obtained by microwave sintering for 30 min at 1300 °C. 相似文献
54.
In this study, a new slip-line field model and its associated hodograph for orthogonal cutting with a rounded-edge worn cutting tool are developed using Dewhurst and Collins's matrix technique. The new model considers the existence of dead metal zone in front of the rounded-edge worn cutting tool. The ploughing force and friction force occurred due to flank wear land, chip up-curl radius, chip thickness, primary shear zone thickness and length of bottom side of the dead metal zone are obtained by solving the model depending on the experimental resultant force data. The effects of flank wear rate, cutting edge radius, uncut chip thickness, cutting speed and rake angle on these outputs are specified. 相似文献
55.
Polymerization of vegetable oils and their uses in printing inks 总被引:4,自引:0,他引:4
Ink vehicles were prepared by the polymerization of vegetable oils. By controlling the polymerization conditions, the desired
viscosity, color and molecular weight could be achieved for a variety of vegetable oils with a broad range of iodine values
and fatty acid compositions. The effect of temperature and catalyst on polymerization rates were evaluated, and polymerization
rate constants were calculated. Of the oils tested, the polymerization rate constant of safflower oil was the highest, followed
by soybean, sunflower, cottonseed and canola oils in decreasing order. Use of a catalyst shortened the heating time by about
25–50% or lowered the polymerization temperature requirement by 25–30°C. 相似文献
56.
Mono- and polyestolides, made from oleic acid, meadowfoam oil fatty acids and erucic acid, were subjected to biodegradation
with mixed cultures of Penicillium verucosum, Mucor racemosus, and Enterobacter aerogenes. Fermentations were continued for 3, 5, 10, 15, 20, or 30 d. Meadowfoam oil and its fatty acids, oleic acid and soybean oil
were also biodegraded under the same conditions. After 10 d, oleic acid and soybean oil were degraded 99.8 and 99.2%, respectively;
meadowfoam oil and its fatty acids were degraded 89.0 and 97.7%, respectively. After 30 d, oleic acid-derived poly- and monoestolides
were degraded 98.6 and 90.0%, respectively, meadowfoam estolides were degraded 75.7%, and erucic acid estolides were degraded
84.0%. 相似文献
57.
Emrah Çimren Bülent Çatay Erhan Budak 《The International Journal of Advanced Manufacturing Technology》2007,35(3-4):363-376
The selection of appropriate machines is one of the most critical decisions in the design and development of an efficient
production environment. In this study, we propose a decision support system for machine tool selection using an effective
algorithm, the analytic hierarchy process. In the selection process, we first consider qualitative decision criteria that
are related to the machine properties. Reliability and precision analyses may be included in the detailed evaluation procedure.
Furthermore, the decision-maker may take into account the economical considerations through cost analysis. In addition, the
robustness of the selection procedure may be evaluated using sensitivity analysis. An illustrative example of machine tool
selection using the proposed methodology and the software implementation are provided. 相似文献
58.
A study on durability properties of high-performance concretes incorporating high replacement levels of slag 总被引:2,自引:1,他引:1
This paper presents an experimental study of combined effects of curing method and high replacement levels of blast furnace
slag on the mechanical and durability properties of high performance concrete. Two different curing methods were simulated
as follows: wet cured (in water) and air cured (at 20°C and 65% RH). The concretes with slag were produced by partial substitution
of cement with slag at varying amounts of 50–80%. The water to cementitious material ratio was maintained at 0.40 for all
mixes. Properties that include compressive and splitting tensile strengths, water absorption by total immersion and by capillary
rise, chloride penetration, and resistance of concrete against damage due to corrosion of the embedded reinforcement were
measured at different ages up to 90 days. It was found that the incorporation of slag at 50% and above-replacement levels
caused a reduction in strength, especially for the early age of air cured specimens. However, the strength increases with
the presence of slag up to 60% replacement for the 90 day wet cured specimens. Test results also indicated that curing condition
and replacement level had significant effects on the durability characteristics; in particular the most prominent effects
were observed on slag blended cement concrete, which performed extremely well when the amount of slag used in the mixture
increased up to 80%. 相似文献
59.
Comparison of total‐etch,self‐etch,and selective etching techniques on class V composite restorations prepared by
Er:YAG laser and bur: a scanning electron microscopy study
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Emre Ozel Elif Bahar Tuna Sonmez Firatli Erhan Firatli 《Microscopy research and technique》2016,79(10):998-1004
The purpose of this study was to compare total‐etch, self‐etch, and selective etching techniques on the marginal microleakage of Class V composite restorations prepared by Er:YAG laser and bur. Class V cavities prepared on both buccal and lingual surfaces of 30 premolars by Er:YAG laser or bur and divided into six groups. The occlusal margins were in enamel, and the cervical margins were in cementum. Group‐1: bur preparation(bp)+Adper Single Bond 2 (ASB)+Filtek Z550 (FZ); Group‐2: laser preparation(lp)+(ASB)+(FZ); Group‐3: bp + Clearfil S3 Bond Plus (CSBP)+(FZ); Group‐4: lp+(CSBP) (FZ); Group‐5: bp + acid etching+(CSBP)+(FZ); Group‐6: lp + acid etching+(CSBP)+(FZ). All teeth were stored in distilled water at 37°C for 24 hr, and then thermocycled 1000 times (5–55°C). Five teeth from each group were chosen for the microleakage investigation, and two teeth for the scanning electron microscope evaluation. Teeth which were prepared for the microleakage test were immersed in .5% methylene blue dye for 24 hr. After immersion, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed using Kruskal–Wallis and Mann–Whitney U tests (p < .05). More microleakage was observed in the cervical regions compared to the occlusal regions in Groups 3, 5, and 6, respectively (p < .05). There is no statistically significant difference in Groups 1, 2, and 4, in terms of cervical regions versus occlusal regions (p > .05). No significant differences were observed among any groups in terms of occlusal and cervical surfaces, separately (p > .05). Different etching techniques did not influence microleakage of Class V restorations prepared by Er:YAG laser and bur. 相似文献
60.
Rail shipments of hazardous materials expose the population near the routes to the possibility of an accident resulting in a spill. Rail routes are determined by economic concerns such as route length and the revenue generated for the originating carrier. In this paper we consider an alternate routing strategy that takes accident risks into account. We employ a model to quantify rail transport risk and then use a weighted combination of cost and risk and generate alternate routes. In some cases the alternate routes achieve significantly lower risk values than the practical routes at a small incremental cost. While there are generally fewer rerouting alternatives for rail than for road transport, considering the possible consequences of a train derailment we argue that risk should be taken into account when selecting rail routes and that the cost-risk tradeoffs should be evaluated. 相似文献