Thermal conductivity of α-Al2O3 was measured using hot wire method. α-Al2O3 (20 nm in size) was synthesized by microwave method for which, the results were compared with commercially available γ-Al2O3. Thermal conductivity of nanofluids was investigated considering, it is dependency on Al2O3 phase. It was observed that by adding 3 wt% of nano γ-Al2O3 and α-Al2O3 to the engine oil, thermal conductivity increases by 37 and 31%, respectively. The corresponding viscosity increase for the
same amount of nano γ-Al2O3 and α-Al2O3 were 36 and 38%, respectively. It was concluded that the differences in thermal conductivity originate from higher specific
surface area of γ-Al2O3 compared to the α-Al2O3 which is the result of porosity difference, obtained during the synthesis process. 相似文献
We give a generalization of the hypergreedy algorithm for minimum weight perfect matching on a complete edge weighted graph whose weights satisfy the triangle inequality. With a modified version of this algorithm we obtain a logn-approximate perfect matching heuristic for points in the Euclidean plane, inO(n log2n) time.This research was supported in part by the DIMACS Grant No. NSF-STC88-09648.This research was supported in part by the NSF under Grant No. CCR 88-07518. 相似文献
In Tong-Viet's, 2012 work, the following question arose: Question.Which groups can be uniquely determined by the structure of their complex group algebras? It is proved here that some simple groups of Lie type are determined by the structure of their complex group algebras. Let p be an odd prime number and S = PSL(2, p2). In this paper, we prove that, if M is a finite group such that S < M < Aut(S), M = ?2 × PSL(2, p2) or M = SL(2, p2), then M is uniquely determined by its order and some information about its character degrees. Let X1(G) be the set of all irreducible complex character degrees of G counting multiplicities. As a consequence of our results, we prove that, if G is a finite group such that X1(G) = X1(M), then G ? M. This implies that M is uniquely determined by the structure of its complex group algebra. 相似文献
The potential application of SWCNTs as mass nanosensors is examined for a wide range of boundary conditions. The SWCNT is modeled via nonlocal Rayleigh, Timoshenko, and higher-order beam theories. The added nano-objects are considered as rigid solids, which are attached to the SWCNT. The mass weight and rotary inertial effects of such nanoparticles are appropriately incorporated into the nonlocal equations of motion of each model. The discrete governing equation pertinent to each model is obtained using an effective meshless technique. The key factor in design of a mass nanosensor is to determine the amount of frequency shift due to the added nanoparticles. Through an inclusive parametric study, the roles of slenderness ratio of the SWCNT, small-scale parameter, mass weight, number of the attached nanoparticles, and the boundary conditions of the SWCNT on the frequency shift ratio of the first flexural vibration mode of the SWCNT as a mass sensor are also discussed. 相似文献
As perishable food supply networks become more complex, incidents of contamination in these supply networks have become fairly common. Added to this complexity is the fact that there have been long delays in identifying the contamination source in several such incidents. Even when the contamination source was identified, there have been cases where the ultimate destination of all contaminated products were not known with complete certainty due, in part, to dispersion in these supply networks. We study the recall dynamics in a three-stage perishable food supply network through three different visibility levels in the presence of contamination. Specifically, we consider allocation of liability among the different players in the perishable supply network based on the accuracy with which the contamination source is identified. We illustrate the significance of finer levels of granularity both upstream and downstream as well as determine appropriate visibility levels and recall policies. 相似文献
The tricyclic isatin, 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione, undergoes three‐component, one‐pot reactions with 1‐aryl‐3‐methylpyrazole‐5‐amines and cyclohexane‐1,3‐diones producing hexacyclic spiro products, hexahydrospiro[pyrazolo[3,4‐b]quinoline‐4,1‐pyrrolo[3,2,1‐ij]quinoline‐2′,5(1H,4′H)‐diones]. Comparable spiro condensation products are also obtained using 4‐hydroxy‐2H‐1‐benzopyran‐2‐one in place of cyclohexane‐1,3‐diones. 相似文献
In the present study, a supramolecular solvent was formed from reverse micelle aggregates of octanol. The proposed supramolecular solvent was used for rapid extraction of some antidepressants drugs including amitriptyline, imipramine, desipramine, maprotiline, sertraline, and doxepin from biological samples. Alkanol‐based supramolecular solvents have a unique array of physicochemical properties, making them a very attractive alternative to replace organic solvents in analytical extractions. The parameters affecting the extraction of target analytes (i.e., the volume of tetrahydrofuran and octanol as the major components comprising the supramolecular solvent, chain length of alkanols, sample solution pH, salt addition, and ultrasonic time) were investigated and optimized by factor by factor optimization method. Under the optimum conditions, preconcentration factors of 470, 490, 460, 385, 370, and 430 were obtained for amitriptyline, doxepin, imipramine, desipramine, maprotiline, and sertraline, respectively. The linear ranges and coefficients of determination (R2) were obtained in the range of 0.01–100 μg/L and 0.9974–0.9991, respectively. Also the limits of detection (S/N = 3) of 0.003–0.03 μg/L, and precisions (n = 5) of 4.9–8.9% were calculated. Finally, the method was successfully applied for the extraction of antidepressant drugs in biological samples, and relative recoveries in the range of 91–102% were obtained. 相似文献
In this research, electrospun polycaprolactam nanofibers were collected on a fine stainless steel mesh sheet without a binder, and a layer of conductive polyaniline was chemically deposited on the nanofibers. The polyaniline immobilized on the polycaprolactam nanofibers provided high electrical conductivity, acceptable mechanical stability, and a large surface area. This assembly was then used as a working electrode in electrochemically controlled solid-phase microextraction (EC-SPME), a fast and environmentally friendly method. The polymer layers were characterized by SEM and FTIR techniques. Significant factors affecting the EC-SPME efficiency were investigated, including the desorption conditions, the sorbent used, the pH of the sample solution, the extraction voltage, the extraction time, and the ionic strength. Under the optimum conditions, the limits of detection and quantification for the target analytes were 0.9–1.8 μg L−1 and 3.0–6.1 μg L−1, respectively. The linear dynamic range was 5–2000 μg L−1, with R2 > 0.993. The method was coupled with HPLC analysis and applied to the determination of angiotensin ΙΙ receptor antagonists (ARA-ΙΙs) in human plasma, and relative recoveries of 91.1–104.3% with RSDs of ≤8.3% were obtained.
Let p(x) be a polynomial of degree n?2 with coefficients in a subfield K of the complex numbers. For each natural number m?2, let Lm(x) be the m×m lower triangular matrix whose diagonal entries are p(x) and for each j=1,…,m−1, its jth subdiagonal entries are . For i=1,2, let Lmi)(x) be the matrix obtained from Lm(x) by deleting its first i rows and its last i columns. L1(1)(x)≡1. Then, the function Bm(x)=x−p(x) defines a fixed-point iteration function having mth order convergence rate for simple roots of p(x). For m=2 and 3, Bm(x) coincides with Newton's and Halley's, respectively. The function Bm(x) is a member of S(m,m+n−2), where for any M?m, S(m,M) is the set of all rational iteration functions g(x) ∈ K(x) such that for all roots θ of p(x), then g(x)=θ+∑i=mMγi(x)(θ−x)i, with γi(x) ∈ K(x) and well-defined at any simple root θ. Given g ∈ S(m,M), and a simple root θ of p(x), gi(θ)=0, i=1, …, m−1 and the asymptotic constant of convergence of the corresponding fixed-point iteration is . For Bm(x) we obtain . If all roots of p(x) are simple, Bm(x) is the unique member of S(m,m + n − 2). By making use of the identity , we arrive at two recursive formulas for constructing iteration functions within the S(m,M) family. In particular, the family of Bm(x) can be generated using one of these formulas. Moreover, the other formula gives a simple scheme for constructing a family of iteration functions credited to Euler as well as Schröder, whose mth order member belongs to S(m,mn), m>2. The iteration functions within S(m,M) can be extended to any arbitrary smooth function f, with the uniform replacement of p(j) with f(j) in g as well as in γm(θ). 相似文献
This research presents calculations and computation of two anticoagulant derivatives electrode potentials in methanol. For this purpose, the ab initio molecular orbital calculations (HF) and density functional theory (DFT) together with the 6-31G(d) basis set were utilized. The calculated values were compared with the experimental values obtained by linear sweep voltammetry. The observed and the calculated changes in the reduction potential of the anticoagulant derivatives differed from those of the reference compound (catechol), being less than 20 mV. In this way, a method was provided, by which the reduction potentials of the related molecules could be predicted very accurately. Actually, the resulting data illustrated that the method was likely to be useful for the prediction of biomolecules electrode potentials in different aprotic solvents. The bond lengths, bond angles and dipole moment of the studied compounds were calculated in two different solvents and the solvent effects were discussed. 相似文献