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51.
Nguyen Huy Dan Pham Thi ThanhNguyen Hai Yen Nguyen Thi Thanh Huyen Duong Dinh Thang Luu Tien Hung 《Journal of magnetism and magnetic materials》2012,324(7):1435-1439
We have observed magnetic anisotropy in bulk Nd55−xCoxFe30Al10B5 (x=10, 15 and 20) alloys prepared by copper mold suction casting method with a presence of external magnetic field (quenching field) μ0H=0.25 T. By changing direction of the measuring field from perpendicular to parallel one in comparison with that of the quenching field, coercive force of the alloys slightly decreases while remanent magnetization and squareness of hysteresis loop increase more clearly. It is also found that the higher Co-concentration in the alloys the larger magnetic anisotropy is induced. The structure analyses manifest nanocrystalline particles embedded in residual amorphous matrix of the alloys. The size of the particles is in range of 10-30 nm and their crystalline phases consist of Nd2(Fe,Co)14B, Nd3Co, Nd3Al, NdAl2 and Nd. 相似文献
52.
I. E. Smirnova H. Do Thi Thu O. B. Kazakova G. A. Tolstikov O. S. Kukovinets A. N. Lobov K. Yu. Suponitskii 《Russian Journal of Organic Chemistry》2012,48(10):1370-1376
Oxidation of dipterocarpol and its derivatives with ozone gave compounds containing lactone, lactol, alkoxytetrahydrofuran, aldehyde, and methyl ketone fragments in the side chain, as well as 1,2,4-trioxolane fragment in the A ring. The molecular and crystalline structures of dipterocarpol were determined by X-ray analysis. 相似文献
53.
Globally solving a nonlinear UAV task assignment problem by stochastic and deterministic optimization approaches 总被引:1,自引:0,他引:1
In this paper, we consider a task allocation model that consists of assigning a set of m unmanned aerial vehicles (UAVs) to a set of n tasks in an optimal way. The optimality is quantified by target scores. The mission is to maximize the target score while
satisfying capacity constraints of both the UAVs and the tasks. This problem is known to be NP-hard. Existing algorithms are
not suitable for the large scale setting. Scalability and robustness are recognized as two main issues. We deal with these
issues by two optimization approaches. The first approach is the Cross-Entropy (CE) method, a generic and practical tool of
stochastic optimization for solving NP-hard problem. The second one is Branch and Bound algorithm, an efficient classical
tool of global deterministic optimization. The numerical results show the efficiency of our approaches, in particular the
CE method for very large scale setting. 相似文献
54.
The financial crisis began with the collapse of Lehman Brothers and the subprime asset backed securities debacle. Credit risk was turned into liquidity risk, resulting in a lack of confidence among financial institutions. In this article, we will propose a way to model liquidity risk and the credit risk in best practices. We will show that liquidity risk is a new type of risk and the current way to deal with it is based solely on observed variables without any theoretical link. We propose an heuristic approach to combine the numerous liquidity risk indicators with a logistic regression for the first time. In regards to credit risk, several articles prove that the best practice is to use an option model to appreciate this risk. We will present our methodology using stochastic diffusion for the interest rate because currently the yield curves aren’t liquid. This approach is more relevant because the basis model in prior publications has a constant interest rate or a forward rate. Both models allow a better understanding of liquidity and credit risks and the further development of research deals with the link between these two financial risks. 相似文献
55.
Qinghua Zhao Thi Tuyet Mai Dang Dong‐Cheol Shin Hong You Soon‐Ki Kwon 《Journal of polymer science. Part A, Polymer chemistry》2007,45(3):341-347
Diphenylaminobiphenylated stryl based alternating copolymers with phenyl or fluorene, which were expected to have a terphenylene vinylene backbone containing an (N,N‐diphenylamino)biphenyl pendant and a phenyl/fluorene/phenylene vinylene backbone containing an (N,N‐diphenylamino)biphenyl pendant, were synthesized by a Suzuki coupling reaction. The obtained copolymers were confirmed with various types of spectroscopy. The alternating copolymers showed good hole‐injection properties because of their low oxidation potential and good solubility and high thermal stability with a high glass‐transition temperature. The alternating copolymers showed blue emissions because of the adjusted conjugation lengths; the maximum wavelength was 460 nm for poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl]vinylene‐alt‐5‐(2′‐ethylhexyloxy)‐2‐methoxybenzene} and 487 nm for poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl] vinylene‐alt‐9,9‐dihexylfluorene}. The maximum brightness of indium tin oxide/poly(3,4‐ethylene dioxythiophene)/polymer/LiF/Al devices with poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl]vinylene‐alt‐5‐(2′‐ethylhexyloxy)‐2‐methoxybenzene} or poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl]vinylene‐alt‐9,9‐dihexylfluorene} as the emitting layer was 250 or 1000 cd/m2, respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 341–347, 2007 相似文献
56.
The cyclization of 1,3-bis-silyl enol ethers or (2,4-dioxobutylidene)triphenylphosphoranes with phthalic dialdehyde allowed a convenient synthesis of a variety of 4,5-benzotropones. The hydrogenation of benzotropones afforded functionalized benzocycloheptanones which were transformed into tricyclic butenolides. 相似文献
57.
Cao Thi Vi Ba Ha Huy Bang Dang Van Soa 《International Journal of Theoretical Physics》2003,42(8):1781-1786
We propose commutation relations for a single mode -deformed para-Bose oscillator. In this new deformation of para-Bose statistics the distribution function has the same form as in the para-Bose statistics. Furthermore, we show analogies between the coherent states of -deformed and q-deformed para-Bose statistics. 相似文献
58.
Tran Duc Thiep Truong Thi An Nguyen The Vinh Phan Viet Cuong A. G. Belov O. D. Maslov Trinh Thi Thu My 《Physics of Particles and Nuclei Letters》2007,4(5):397-402
We have carried out the study on the isomeric ratios in (γ,p) photonuclear reactions with isotopes
40
92
Zr and
74
183
W in the giant dipole resonance (GDR) region. The targets were irradiated with bremsstrahlungs produced by electron accelerator
Microtron MT-25 of the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, Russia. Spectra
of the irradiated samples were measured with a spectroscopic system consisting of 8192-channel analyzer CANBERRA and high-energy
resolution semiconductor detector CANBERRA. The results were discussed and compared with those of other authors.
The text was submitted by the authors in English. 相似文献
59.
Ngoc Vinh Huynh Thi Hoai Thu Nguyen Kim Phi Phung Nguyen Poul Erik Hansen 《Magnetic resonance in chemistry : MRC》2013,51(7):439-443
Tithonia tagetiflora Desv. (Asteraceae) is a widespread plant in Vietnam, and the species of Tithonia are known as plants containing many biologically active compounds. However, T. tagetiflora's chemical composition remains mostly unknown. Therefore, we now report the structural elucidation of two new sesquiterpene lactones, 8‐angeloyloxy‐2,14‐epoxygermacra‐4,10(1),11(13)‐trien‐6,12‐olide (1) and 6‐angeloyloxy‐1‐hydroxy‐3,4‐epoxygermacra‐9,11(13)‐dien‐8,12‐olide (2), together with three known compounds, including two norisoprenoids, (6S,9S)‐vomifoliol or (6R,9R)‐vomifoliol (3) and (6S,9S)‐roseoside (4), and one glutinane type triterpene, epi‐glutinol (5), from the leaves of T. tagetiflora. Their structures are established by 1D and 2D NMR spectroscopy, as well as ESI‐MS analysis and comparison with literature data. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
60.
Ph. Pruzan J. C. Chervin M. M. Thiéry J. P. Itié J. M. Besson J. P. Forgerit 《高压研究》2013,33(1-6):215-217
Abstract After a pressure cycle to 30 GPa, benzene transforms to a white solid which can be recovered at ambient. Results obtained from infrared spectroscopy and other physico-chemical methods show that the recovered solid is a highly cross-linked polymer. The molecular structure of benzene is very likely completely altered by the transformation. 相似文献