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91.
M. Charef Mohamed Yousfi M. Saidi P. Stocker 《Journal of the American Oil Chemists' Society》2008,85(10):921-924
The fruits of two plants from Algeria (Quercus and Pistacia lentiscus) were investigated. The paper reports the chemical characteristics and the fatty acid composition of the oil extracts from
the fruits. The black fruits of P. lentiscus has the highest crude fat of 32.8%, followed by the red fruits with 11.7%, and the lowest value of 9% in Quercus (acorn). The acid value was highest in red fruits of P. lentiscus oil (24.0 mg KOH/g), followed by the black fruits oil and lowest in acorn oil. The relatively high iodine value in the oils
indicates the presence of many unsaturated bonds. Saponification value was highest in the Quercus ilex oil (166.7 mg KOH/g), while the lowest value was in the black fruits of P. lentiscus oil. Gas-liquid chromatography revealed that the three dominant fatty acids found are: palmitic C16:0 (16.3–19.5%), oleic
C18:1 (55.3–64.9%), linoleic C18:2 (17.6–28.4%). The oils contain an appreciable amount of unsaturated fatty acids (78.8–83.5%). 相似文献
92.
M. Zarezadeh Mehrizi M. Shamanian A. Saidi 《Journal of Materials Engineering and Performance》2014,23(2):451-457
In this study, Co(ss)/WSi2-CoWSi nanocomposite was synthesized via mechanical alloying and heat treatment. In order to fabricate bulk composite, 50-h-milled powders were cold pressed and subsequently sintered at 1150 °C for 4 h in Ar atmosphere. Phase development and structural changes were investigated by x-ray diffraction technique and scanning electron microscopy. After various milling times, the powders were investigated by differential thermal analysis and microhardness measurements. The starting powder mixture has two allotropic structures of Co (fcc and hcp). After 10-h milling, an allotropic transformation takes place in Co (fcc to hcp), and a composite microstructure consisting of cold-welded Co, W, and Si phases is formed. After 20 h, new peaks related to WSi2 appeared in x-ray diffractograms. Increasing milling time to 50 h caused the formation of (Co, W, and Si) solid solution, WSi2, and CoWSi phases. DTA analysis of 30- and 50-h-milled powders confirmed an increase in the degree of ordering. The 50-h-milled powders exhibited high microhardness value of about 1050 HV0.1. XRD result of sintered material demonstrated that only ordered Co(ss)/WSi2-CoWSi nanostructured composite is present. Consolidated sample showed 12% porosity. Nanoindentation results showed that the sintered composite an exhibited a high hardness of 700 HV0.1 with an elastic modulus of 107 GPa. 相似文献
93.
Static and dynamic performance evaluation of a commercially-available ultra wideband tracking system
Kamel S. Saidi Jochen Teizer Marek Franaszek Alan M. Lytle 《Automation in Construction》2011,20(5):519-530
Locating and tracking resources (e.g., people, equipment, and materials) is critical in many industrial applications for monitoring productivity and safety. In construction, various technologies (e.g., global positioning systems (GPS), radio frequency identification (RFID) and radio frequency (RF) localization) have been proposed. However, the performance of these types of technologies is not well understood for this particular application. This paper presents a study for evaluating the static and dynamic performance of a commercially-available ultra wideband (UWB) tracking system in free space and under realistic construction environments. In addition, a static performance model for estimating position error as a function of receiver position and initial calibration error was also developed. Results and experiences are in particular useful for researchers or practitioners in need for adapting UWB technology for their application. 相似文献
94.
Fatemeh Rajabi Nafiseh Karimi Mohammad Reza Saidi Ana Primo Rajender S. Varma Rafael Luque 《Advanced Synthesis \u0026amp; Catalysis》2012,354(9):1707-1711
Iron oxide nanoparticles supported on mesoporous silica‐type materials have been successfully utilized in the aqueous selective oxidation of alkenes under mild conditions using hydrogen peroxide as green oxidant. The supported catalyst could be easily recovered after completion of the reaction and reused several times without any loss in activity (no metal leaching observed during the reaction), constituting a facile and straightforward example of aqueous oxidation chemistry promoted by iron‐based heterogeneous systems. 相似文献
95.
Arman Sadeghi Mohammad Hassan Saidi 《International Journal of Heat and Mass Transfer》2010,53(19-20):3782-3791
This study investigates the influence of viscous dissipation on thermal transport characteristics of the fully developed combined pressure and electroosmotically driven flow in parallel plate microchannels subject to uniform wall heat flux. Closed form expressions are obtained for the transverse distributions of electrical potential, velocity and temperature and also for Nusselt number. From the results it is realized that the Brinkman number has a significant effect on Nusselt number. Generally speaking, to increase Brinkman number is to decrease Nusselt number. Although the magnitude of Joule heating can affect Brinkman number dependency of Nusselt number, however the general trend remains unchanged. Depending on the value of flow parameters, a singularity may occur in Nusselt number values even in the absence of viscous heating, especially at great values of dimensionless Joule heating term. For a given value of Brinkman number, as dimensionless Debye–Huckel parameter increases, the effect of viscous heating increases. In this condition, as dimensionless Debye–Huckel parameter goes to infinity, the Nusselt number approaches zero, regardless of the magnitude of Joule heating. Furthermore, it is realized that the effect of Brinkman number on Nusselt number for pressure opposed flow is more notable than purely electroosmotic flow, while the opposite is true for pressure assisted flow. 相似文献
96.
Aiming at improving efficiency in combustion systems, the study on droplet behavior and its trajectory is of crucial importance.
Vortex engine is a kind of internal combustion engine which uses swirl flow to achieve higher combustion efficiency. One of
the important advantages of designing vortex engine is to reduce the temperature of walls by confining the combustion products
in the inner vortex. The scopes of this investigation are to study vortex engine flow field as well as effective parameters
on fuel droplet behavior such as droplet diameter, droplet initial velocity and inlet velocity of the flow field. The flow
field is simulated using Reynolds Stress Transport Model (RSM). The Eulerian-Lagrangian method and the one-way coupling approach
are employed to simulate two phase flow and dispersed phase in the chamber, respectively. A new method, based on computing
pressure force exerted on the droplet surface, is introduced to determine the distinction between using one-way and two-way
coupling approaches. The results showed that the droplets with smaller diameter are more likely to follow the flow stream
lines than bigger droplets, thus evaporate completely in the chamber. Moreover, droplets with greater initial velocity have
higher evaporation rate, yielding the existence of evaporation and combustion in the inner vortex. Additionally, the higher
inlet velocity of continuous phase results in higher centrifugal force, leads droplets in question to deviate towards the
wall faster. 相似文献
97.
Omid Asgari Mohammad Hassan Saidi 《Journal of Mechanical Science and Technology》2009,23(12):3448-3458
Microchannels are at the forefront of today’s cooling technologies. They are widely being considered for cooling of electronic
devices and in micro heat exchanger systems due to their ease of manufacture. One issue which arises in the use of microchannels
is related to the small length scale of the channel or channel cross-section. In this work, the maximum heat transfer and
the optimum geometry for a given pressure loss have been calculated for forced convective heat transfer in microchannels of
various cross-section having finite volume for laminar flow conditions. Solutions are presented for 10 different channel cross
sections: parallel plate channel, circular duct, rectangular channel, elliptical duct, polygonal duct, equilateral triangular
duct, isosceles triangular duct, right triangular duct, rhombic duct and trapezoidal duct. The model is only a function of
the Prandtl number and the geometrical parameters of the cross-section, i.e., area and perimeter. This solution is performed
with two exact and approximate methods. Finally, in addition to comparison and discussion of these two methods, validation
of the relationship is provided using results from the open literature. 相似文献
98.
The effects of the geometrical asymmetric related to tip position as a concentrated mass, on the sensitivity of all three vibration modes, lateral excitation (LE), torsional resonance (TR) and vertical excitation (VE), of an atomic force microscopy (AFM) microcantilever have been analyzed. The effects of the tip mass and its position are studied to report the novel results to estimating the vibration behavior of AFM such as resonance frequency and amplitude of the microcantilever. In this way, to achieve more accurate results, the coupled motion in all three modes is considered. In particular, it is investigated that performing the coupled motion in analysis of AFM microcantilever is almost necessary. It is shown that the tip mass and its position have significant effects on vibrational responses. The results show that considering the tip mass decreases the resonance frequencies particularly on high-order modes. However, dislocating of tip position has an inverse effect that causes an increase in the resonance frequencies. In addition, it has been shown that the amplitude of the AFM microcantilever is affected by the influences of tip and its position. These effects are caused by the interaction between flexural and torsional motion due to the moment of inertia of the tip mass. 相似文献
99.
Hidouri Tarek Saidi Faouzi Hamila Radhia Al-Shahri Badria M. 《Journal of Materials Science: Materials in Electronics》2021,32(15):20115-20129
Journal of Materials Science: Materials in Electronics - In this work, quaternary BInGaAs single quantum wells have been grown on GaAs substrate by metal–organic vapor-phase epitaxy. The... 相似文献
100.