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Dimitri Volchenkov Jonathan Helbach Marko Tscherepanow Sina Kühnel 《Journal of the Royal Society Interface》2013,10(85)
Searching experiments conducted in different virtual environments over a gender-balanced group of people revealed a gender irrelevant scale-free spread of searching activity on large spatio-temporal scales. We have suggested and solved analytically a simple statistical model of the coherent-noise type describing the exploration–exploitation trade-off in humans (‘should I stay’ or ‘should I go’). The model exhibits a variety of saltatory behaviours, ranging from Lévy flights occurring under uncertainty to Brownian walks performed by a treasure hunter confident of the eventual success. 相似文献
113.
Energy storage is needed for renewable systems due to the intermittent nature of wind and solar energy. Hydrogen can be used to store variable renewable energy such as solar and wind energy. According to this fact, there is an increasing interest in use of solar-hydrogen systems for power supply in remote areas or other standalone applications. One of these applications is Hydrogen production station working by solar energy to use in fuel cell vehicle. Time consuming aspect of solar-hydrogen production is the most prominent reason for presenting a new scheme as a parking-refueling station for fuel cell vehicles in this study. To do this, Simulation, economic and environmental evaluations of the solar parking-refueling station are considered in this article. Because of using an independent hydrogen compression system, the suggested parking-refueling station can be used in a standalone area such as rural and military applications. Results show that the proposed system seems to be economic in present condition. It also illustrates that the Levelized Cost of Product (Km-Passenger) is in a range of 0.15–0.28 US$. Although using the tracker system is not economically efficient, the effect of such a structure is more obvious in the points far from tropical area. 相似文献
114.
Alexander Epishin Bernard Fedelich Gert Nolze Sina Schriever Titus Feldmann Muhammad Farzik Ijaz Bernard Viguier Dominique Poquillon Yann Le Bouar Antoine Ruffini Alphonse Finel 《Metallurgical and Materials Transactions A》2018,49(9):3973-3987
The creep behavior of single crystals of the nickel-based superalloy CMSX-4 was investigated at 1288 °C, which is the temperature of the hot isostatic pressing treatment applied to this superalloy in the industry. It was found that at this super-solvus temperature, where no γ′-strengthening occurs, the superalloy is very soft and rapidly deforms under stresses between 4 and 16 MPa. The creep resistance was found to be very anisotropic, e.g., the creep rate of [001] crystals was about 11 times higher than that of a [111] crystal. The specimens of different orientations also showed a very different necking behavior. The reduction of the cross-sectional area ψ of [001] crystals reached nearly 100 pct, while for a [111] crystal ψ?=?62 pct. The EBSD analysis of deformed specimens showed that despite such a large local strain the [001] crystals did not recrystallize, while a less deformed [111] crystal totally recrystallized within the necking zone. The recrystallization degree was found to be correlated with deformation behavior as well as with dwell time at high temperature. From the analysis of the obtained results (creep anisotropy, stress dependence of the creep rate, traces of shear deformation, and TEM observations), it was concluded that the main strain contribution resulted from 〈\( 0 1\bar{1} \)〉{111} octahedral slip. 相似文献
115.
Pritesh Hiralal Sina Saremi-YarahmadiHaolan Wang Stephan HofmannK.G. Upul Wijayantha Gehan A.J. Amaratunga 《Solar Energy Materials & Solar Cells》2011,95(7):1819-1825
We report on a facile low temperature method for the preparation of high surface area, nanostructured α-Fe2O3 (hematite) thin films and their application as photoelectrochemical (PEC) water splitting electrodes. The hematite films are fabricated by thermal oxidation in air of DC sputter deposited iron films at temperatures as low as 255 °C. This method results in films with a higher surface area than typically obtained by directly sputtering α-Fe2O3. It is shown that beyond a minimum iron thickness, α-Fe2O3 nanowires result upon thermal treatment in atmospheric conditions. Structural and optical characteristics of the resulting films are analyzed. The oxidation process is studied in detail and correlated to the photoelectrical properties. The Fe films oxidize in stages via Fe-oxide layers of increasing oxidation states. Resulting photoelectrochemical performance of fully oxidized films is a balance between optical absorption and charge collection, which varies with film thickness. The optimum film achieved a net photocurrent density of 0.18 mA/cm2 in 1 M NaOH at 1.23 V vs. RHE under simulated AM1.5 sunlight, amongst the highest values reported for undoped hematite films produced at low temperature. 相似文献
116.
Sina Cosmulescu Ion Trandafir Violeta Nour 《International Journal of Food Properties》2017,20(12):3124-3134
In this study, the total phenolic, total flavonoids, phenolic compounds, the mineral content, and antioxidant activity of fruit extracts of seven wild species (Crataegus monogyna Jacq., Prunus spinosa L., Rosa canina L., Hippophaë rhamnoides L., Rubus fruticosus L., Prunus padus, Cornus mas L.) were investigated. The results indicated significant differences (p < 0.05) in the total phenolics and total flavonoids content, between the seven analyzed species. These ranged from 184.69 to 727.29 mg GAE/100 g FW and 17.27 to –165.55 mg QE/100 g FW, respectively. The antioxidant activity found in fruits was not directly affected by the total phenolic content (TPC). This activity was linked to a larger extent to the type of individual phenolic compounds and to a lesser extent to the TPC, because fruits with higher TPC have not always presented the highest values of antioxidant activity. HPLC analysis of methanolic extract showed the presence of phenolic acids (i.e. gallic, vanillic, chlorogenic, caffeic, syringic, p-coumaric, ferulic, sinapic, salycilic, elagic, and trans-cinnamic) and flavonoids (i.e. catechin, epicatechin, rutin, myricetin, and quercetin). Significant differences (p < 0.05) were observed in each individual mineral between fruits from wild flora. The fruits tissues of wild species turned out to be a good source of calcium (Ca), magnesium (Mg), sodium (Na), iron (Fe), manganese (Mn), copper (Cu), chromium (Cr), zinc (Zn), and boron (B). The results demonstrated that wild species possessed great potential for food production as sources of bioactive compounds such as phenolic compounds and minerals, for food supplements or functional foods. 相似文献
117.
Sina Esmaeeli Hadi Salamati Ali Ghasemi Parviz Kameli 《Journal of Superconductivity and Novel Magnetism》2016,29(7):1827-1835
A series of 60-nm FePt thin films were deposited by RF magnetron sputtering system on Si/SiO2 substrate. Platinum–iridium alloy was deposited as a buffer film between the FePt thin film and Si/SiO2 substrate. These films were annealed by KrF excimer laser annealing with 248 nm of wavelength. The number of laser pulses which were applied on the film was varied from 3 to 20. The A1 to L10 phase transformation of FePt was confirmed by X-ray diffraction. Three pulses of laser were not sufficient for A1 to L10 phase transformation. A maximum order parameter of 0.91 was obtained after applying 18 pulses of laser. The roughness of films changed in different pulses, and the films were in the best condition after applying 18 pulses; the roughness was 3.51 nm and its morphology that was observed from AFM was 129 nm. The maximum coercivity was 0.61 MA/m. The coercivity increased with the application of different pulses of laser. Increasing coercivity to the maximum value of 0.61 MA/m related to grain growth. Coercivity of samples in 3, 6, 9, 12, 18, and 20 pulses was 0.24, 0.402, 0.488, 0.522, 0.64, and 0.6 MA/m respectively. Determining the grain growth under condition of annealing was done by field emission scanning electron microscopy (FESEM). Growth of all specimens was calculated with imager software. Grain size in as deposited and 3, 6, 9, 12, and 18 pulses of laser was 15, 20, 29, 44, 47, and 59 respectively. 相似文献
118.
Kron reduction is used to simplify the analysis of multi-machine power systems under certain steady state assumptions that underly the usage of phasors. Using ideas from behavioral system theory, in this paper we show how to perform Kron reduction for a class of electrical networks, called homogeneous electrical networks, without steady state assumptions. The reduced models can thus be used to analyze the transient as well as the steady state behavior of these electrical networks. 相似文献
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120.
Seyed Mohammad Sina Mousavi Hossein Ganjidoust 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(22):3300-3307
In this study, a single-chamber microbial fuel cell (SCMFC) was used to simultaneously remove 300 mg/l phenol and generate bio-electricity. During the tests, temperature and salt content were increased from 25 to 45°C and from 0.5 to 2% (w/v), respectively. The results show that at 45°C, the removal rate increased 4 and 5%, respectively; meanwhile, power density peak increased from 34 to 43 mW/m2. Phenol removal rate increased 4% by adding 0.5% salt. The power density peak increased greatly to 45 mW/m2 after adding 1% salt to the anolyte. Initial phenol concentration was consistent for all tests and cycles for 72 h. The study demonstrates that this method can be used to remove phenol and generate bio-electricity in different conditions. 相似文献