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91.
Behrooz Alizadeh Rainer E. Burkard 《Central European Journal of Operations Research》2013,21(3):585-594
For an inverse obnoxious center location problem, the edge lengths of the underlying network have to be changed within given bounds at minimum total cost such that a predetermined point of the network becomes an obnoxious center location under the new edge lengths. The cost is proportional to the increase or decrease, resp., of the edge length. The total cost is defined as sum of all cost incurred by length changes. For solving this problem on a network with m edges an algorithm with running time ${\mathcal{O}(m)}$ is developed. 相似文献
92.
An SO3H‐functionalized nano‐MGO‐D‐NH2 catalyst has been prepared by multi‐functionalization of a magnetic graphene oxide (GO) nanohybrid and evaluated in the synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3‐d]pyrimidinone derivatives. The GO/Fe3O4 (MGO) hybrid was prepared via an improved Hummers method followed by the covalent attachment of 1,4‐butanesultone with the amino group of the as‐prepared polyamidoamine‐functionalized MGO (MGO‐D‐NH2) to give double‐functionalized magnetic nanoparticles as the catalyst. The prepared nanoparticles were characterized to confirm their synthesis and to precisely determine their physicochemical properties. In summary, the prepared catalyst showed marked recyclability and catalytic performance in terms of reaction time and yield of products. The results of this study are hoped to aid the development of a new class of heterogeneous catalysts to show high performance and as excellent candidates for industrial applications. 相似文献
93.
Selective oxidation of sulfides to sulfoxides is achieved using H2O2 and TMSCl as the promotor. Aromatic and aliphatic sulfides are oxidized to sulfoxides in excellent yields and in short reaction times. Different functional groups including ketone, alkene, ester, and alcohol are tolerated. 相似文献
94.
The essential oil components of geranium oil cultivated in center of Iran were identified and determined using gas chromatography-mass spectrometry data combined with the chemometric resolution techniques. A total of 61 components accounting for 91.51% were identified using similarity searches between the mass spectra and MS database. This number was extended to 85 components using chemometric techniques. Various chemometric methods such as morphological scores, simplified Borgen method (SBM) and fixed size moving window evolving factor analysis (FSMWEFA) were used for determining the number of components, pure variables, zero concentration and selective regions. Then the overlapping peak clusters were resolved into pure chromatograms and pure mass spectra using heuristic evolving latent projections (HELP) method. A characteristic feature of the Iranian geranium oil is the absence of 10-epi-gamma-eudesmol in its constituents compared with the oil from northern and southern parts of India. The results of this work show that combination of hyphenated chromatographic methods and resolution techniques provide a complementary method for accurate analysis of essential oils. 相似文献
95.
Fahimeh Baroughi Bonab Rainer E. Burkard Behrooz Alizadeh 《Central European Journal of Operations Research》2010,18(3):365-381
Given n points in
\mathbbRd{\mathbb{R}^d} with nonnegative weights, the inverse 1-median problem with variable coordinates consists in changing the coordinates of
the given points at minimum cost such that a prespecified point in
\mathbbRd{\mathbb{R}^d} becomes the 1-median. The cost is proportional to the increase or decrease of the corresponding point coordinate. If the
distances between points are measured by the rectilinear norm, the inverse 1-median problem is NP{\mathcal{NP}}-hard, but it can be solved in pseudo-polynomial time. Moreover, a fully polynomial time approximation scheme exists in this
case. If the point weights are assumed to be equal, the corresponding inverse problem can be reduced to d continuous knapsack problems and is therefore solvable in O(nd) time. In case that the squared Euclidean norm is used, we derive another efficient combinatorial algorithm which solves
the problem in O(nd) time. It is also shown that the inverse 1-median problem endowed with the Chebyshev norm in the plane is NP{\mathcal{NP}}-hard. Another pseudo-polynomial algorithm is developed for this case, but it is shown that no fully polynomial time approximation
scheme does exist. 相似文献
96.
I. M. de Schepper E. G. D. Cohen B. Kamgar-Parsi 《Journal of statistical physics》1989,54(1-2):273-313
We discuss in detail techniques that have been used to determine single-particle equilibrium time correlation functions in a hard-sphere fluid on the basis of kinetic theory. The accuracy of various procedures is assessed.On leave from Interuniversitair Reactor Instituut, Delft, The Netherlands. 相似文献
97.
Microchimica Acta - The authors report on the preparation of sol-gel coated magnetized carbon nanotubes whose surface were imprinted with Cd2+ ions and the application of these materials on... 相似文献
98.
Let G be a finite group. The main result of this paper is as follows: If G is a finite group, such that Γ(G) = Γ(2G2(q)), where q = 32n+1 for some n ≥ 1, then G has a (unique) nonabelian composition factor isomorphic to 2 G 2(q). We infer that if G is a finite group satisfying |G| = |2 G 2(q)| and Γ(G) = Γ (2 G 2(q)) then G ? = 2 G 2(q). This enables us to give new proofs for some theorems; e.g., a conjecture of W. Shi and J. Bi. Some applications of this result are also considered to the problem of recognition by element orders of finite groups. 相似文献
99.
Gas chromatography-mass spectrometry combined with iterative and non-iterative resolution methods was used to characterize the essential oil components of Iranian cumin and caraway. Orthogonal projection resolution (OPR) as a non-iterative and distance-selection-multivariate curve resolution-alternative least squares (DS-MCR-ALS) as an iterative method were used as auxiliary means to the analysis in the case of overlapping peaks. A total of 19 and 39 components were identified by direct similarity searches for cumin and caraway oils, respectively. These numbers were extended to 49 and 98 components, respectively with the help of chemometric techniques. Major constituents in cumin are gamma-terpinene (15.82%), 2-methyl-3-phenyl-propanal (32.27%) and myrtenal (11.64%) and in caraway are gamma-terpinene (24.40%), 2-methyl-3-phenyl-propanal (13.20%) and 2, 4(10)-thujadien (14.02%). In spite of different cultivation conditions, there are 28 components which are common between the two seeds. 相似文献
100.
The main purpose of this paper is to investigate the control and stability of a tractor moving over obstacles on steep side slopes. To this end, a modified slope tractor is considered and the lateral stability of the vehicle is studied. The modified tractor is able to roll against the side slope and change the position of its mass centre. The tractor behaviour in a sloped field on a straight path is simulated in ADAMS software environment. A two-layer controller consisting of a Fuzzy upper layer and a PI lower layer is designed for the control of tractor stability. The dynamics of hydraulic actuators adjusting the body roll angle is also included. The stability of controlled and uncontrolled tractors is investigated by several simulations. It is shown that in comparison with the two types of ordinary and uncontrolled slope tractors, the controller is capable of maintaining the stability of modified tractor and preventing it from rollover and instability on various side slopes and obstacles. 相似文献