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91.
The paper formulates an extension of the traveling purchaser problem where multiple types of commodities are sold at spatially distributed locations with stochastic prices (each following a known probability distribution). A purchaser’s goal is to find the optimal routing and purchasing strategies that minimize the expected total travel and purchasing costs needed to purchase one unit of each commodity. The purchaser reveals the actual commodity price at a seller upon arrival, and then either purchases the commodity at the offered price, or rejects the price and visits a next seller. In this paper, we propose an exact solution algorithm based on dynamic programming, an iterative approximate algorithm that yields bounds for the minimum total expected cost, and a greedy heuristic for fast solutions to large-scale applications. We analyze the characteristics of the problem and test the computational performance of the proposed algorithms. The numerical results show that the approximate and heuristic algorithms yield near-optimum strategies and very good estimates of the minimum total cost. 相似文献
92.
93.
94.
The Dieudonn-Manin classification theorem on φ-modules (φ-isocrystals) over a perfect field plays a very important role in p-adic Hodge theory. In this note, in a more general setting we give a new proof of this result, and in the course of the proof, we also give an explicit construction of the Harder-Narasimhan filtration of a φ-module. 相似文献
95.
A semi‐implicit characteristic‐based split (CBS) meshfree algorithm in the arbitrary Lagrangian Eulerian (ALE) framework is proposed for the numerical solution of incompressible free surface flow problem in the paper. The algorithm is the extension of general CBS method which was initially introduced in finite element framework, this is due to the fact that CBS method not only can enhance the stability, but also avoid LBB condition when equal order basis function is used to approximate velocity and pressure variables. Meanwhile, a simple way for node update and node speed calculation is developed which is used to capture the free surface exactly. The numerical solutions are compared with available analytical and numerical solutions, which shows that the proposed method has better ability to simulate the free surface incompressible flow problem. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
96.
Dian Niu Yuqian Jiang Lukang Ji Guanghui Ouyang Minghua Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(18):6007-6011
Multiple noncovalent interactions can drive self‐assembly through different pathways. Here, by coordination‐assisted changes in π‐stacking modes between chromophores in pyrene‐conjugated histidine (PyHis), a self‐assembly system with reversible and inversed switching of supramolecular chirality, as well as circularly polarized luminescence (CPL) is described. It was found that l ‐PyHis self‐assembled into nanofibers showing P‐chirality and right‐handed CPL. Upon ZnII coordination, the nanofibers changed into nanospheres with M‐chirality, as well as left‐handed CPL. The process is reversible and the M‐chirality can change to P‐chirality by removing the ZnII ions. Experimental and theoretical models unequivocally revealed that the cooperation of metal coordination and π‐stacking modes are responsible the reversible switching of supramolecular chirality. This work not only provides insight into how multiple noncovalent interactions regulate self‐assembly pathways. 相似文献
97.
A novel bifunctional blue-light material, 9-(pyren-1-yl)-9H-carbazole (CzPy), has been syn-thesized and its structure is identified by electron ionization mass spectrometry, 1H NMR, and element analysis. The absorption, photoluminescence spectra and thermal properties were studied, results showedthat CzPy was stable under ambient conditions with a blue-light emission (461 nm).Additionally, its electroluminescence properties were characterized with four different devices. Results indicated a maximum luminous efficiency reached 1.56 cd/A and maximum luminance up to 3526 cd/m2 at 10 V with commission international De L'Eclairage coordinates of (0.20, 0.24) when it was used as emitter. Furthermore, CzPy also indicated hole-transporting ability. 相似文献
98.
A biosensor based on graphene nanoribbon with nanopores: a first-principles devices-design 下载免费PDF全文
A biosensor device,built from graphene nanoribbons(GNRs) with nanopores,was designed and studied by firstprinciples quantum transport simulation.We have demonstrated the intrinsic transport properties of the device and the effect of different nucleobases on device properties when they are located in the nanopores of GNRs.It was found that the device’s current changes remarkably with the species of nucleobases,which originates from their different chemical compositions and coupling strengths with GNRs.In addition,our first-principles results clearly reveal that the distinguished ability of a device’s current depends on the position of the pore to some extent.These results may present a new way to read off the nucleobases sequence of a single-stranded DNA(ssDNA) molecule by such GNRs-based device with designed nanopores 相似文献
99.
The accelerator-generating 6.13~MeV pulsed Gamma by
19F(p, αγ )160 reaction usually synchronizes
with an intense bremsstrahlung x-ray which has a maximum energy of
1~MeV. This paper proposes a new method, named the scattering and
absorbing method, to diagnose the 6.13~MeV Gamma. This method
includes two parts: the detector and a scatterer placed in front of
the detector. The detector converts the Gamma to electrons and then
collects the electrons by a scintillator. In order to restrain the
interference of the low-energy background, the scintillator collects the
electrons at a small angle. The scintillator is wrapped with
electro-absorbing material to absorb the low-energy electrons
generated by background x-rays. The theoretical sensitivity ratio of
6.13~MeV Gamma to 1~MeV x-rays is greater than 150. The scatterer is a
pretreatment tool to scatter some background x-rays away from the
radial beam before they enter the detector. By varying the length,
the scatterer can reduce the background x-rays to an acceptable level for
the detector. 相似文献
100.
Gefu Ji Zhenyu Ouyang Guoqiang Li Samuel Ibekwe Su-Seng Pang 《International Journal of Solids and Structures》2010,47(18-19):2445-2458
The interfacial fracture of adhesively bonded structures is a critical issue for the extensive applications to a variety of modern industries. In the recent two decades, cohesive zone models (CZMs) have been receiving intensive attentions for fracture problems of adhesively bonded joints. Numerous global tests have been conducted to measure the interfacial toughness of adhesive joints. Limited local tests have also been conducted to determine the interface traction-separation laws in adhesive joints. However, very few studies focused on the local test of effects of adhesive thickness on the interfacial traction-separation laws. Interfacial toughness and interfacial strength, as two critical parameters in an interfacial traction-separation law, have important effect on the fracture behaviors of bonded joints. In this work, the global and local tests are employed to investigate the effect of adhesive thickness on interfacial energy release rate, interfacial strength, and shapes of the interfacial traction-separation laws. Basically, the measured laws in this work reflect the equivalent and lumped interfacial fracture behaviors which include the cohesive fracture, damage and plasticity. The experimentally determined interfacial traction-separation laws may provide valuable baseline data for the parameter calibrations in numerical models. The current experimental results may also facilitate the understanding of adhesive thickness-dependent interface fracture of bonded joints. 相似文献