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41.
Solving the two-echelon location routing problem by a GRASP reinforced by a learning process and path relinking 总被引:1,自引:0,他引:1
Viet-Phuong Nguyen Christian Prins Caroline Prodhon 《European Journal of Operational Research》2012,216(1):113-126
The two-echelon location-routing problem (LRP-2E) arises from recent transportation applications like city logistics. In this problem, still seldom studied, first-level trips serve from a main depot a set of satellite depots, which must be located, while second-level trips visit customers from these satellites. After a literature review on the LRP-2E, we present four constructive heuristics and a hybrid metaheuristic: A greedy randomized adaptive search procedure (GRASP) complemented by a learning process (LP) and path relinking (PR). The GRASP and learning process involve three greedy randomized heuristics to generate trial solutions and two variable neighbourhood descent (VND) procedures to improve them. The optional path relinking adds a memory mechanism by combining intensification strategy and post-optimization. Numerical tests show that the GRASP with LP and PR outperforms the simple heuristics and an adaptation of a matheuristic initially published for a particular case, the capacitated location-routing problem (CLRP). Additional tests on the CLRP indicate that the best GRASP competes with the best metaheuristics published. 相似文献
42.
F. Fahrni M.W.J. Prins L.J. van IJzendoorn 《Journal of magnetism and magnetic materials》2009,321(12):1843-1850
An increasing number of lab-on-a-chip devices require advanced fluid manipulations. We intend to address this requirement by incorporating polymeric responsive materials on the walls of the microfluidic channels of such devices. In this paper we present a magnetic polymer made from commercially available functionalized magnetic nanoparticles and PDMS. Loadings of this polymer up to 5% volume of magnetic material were achieved. We report on the Young's modulus of this material and describe its magnetization behavior with a combination of inter-particle interaction and particle cluster demagnetization effects. The magnetic polymer can have a magnetic susceptibility up to 0.5 and by curing in a magnetic field, a magnetic anisotropy of a factor 2 in susceptibility can be created. Finally, a finite element model simulation is performed to quantify the amplitude of motion of a microstructure made of this magnetic polymer, and the local magnetic actuation with a current running in a micro-fabricated wire is discussed. 相似文献
43.
Tshakane Tshepe Johan F. Prins Michael J. R. Hoch 《Czechoslovak Journal of Physics》1996,46(5):2439-2440
We have investigated low-temperature electrical transport mechanisms in the surface layer of a type IIa diamond which has been heavily implanted with boron-ions at low temperatures and then annealed at high temperatures. The boron atoms occupy substitutional sites giving rise to a heavily doped wide-bandgap semiconductor. The dc-conductivity results suggest that for the maximum boron doping that has been achieved, the diamond sample is close to the insulator-metal transition. A model to account for the observed increase in activated boron centres with ion dose is presented. On the insulating side of the transition, the data are interpreted in terms of variable-range hopping laws. 相似文献
44.
Solving the capacitated location-routing problem by a GRASP complemented by a learning process and a path relinking 总被引:1,自引:0,他引:1
Christian Prins Caroline Prodhon Roberto Wolfler Calvo 《4OR: A Quarterly Journal of Operations Research》2006,4(3):221-238
As shown in recent researches, the costs in distribution systems may be excessive if routes are ignored when locating depots. The location routing problem (LRP) overcomes this drawback by simultaneously tackling location and routing decisions. This paper presents a new metaheuristic to solve the LRP with capacitated routes and depots. A first phase executes a GRASP, based on an extended and randomized version of Clarke and Wright algorithm. This phase is implemented with a learning process on the choice of depots. In a second phase, new solutions are generated by a post-optimization using a path relinking. The method is evaluated on sets of randomly generated instances, and compared to other heuristics and a lower bound. Solutions are obtained in a reasonable amount of time for such a strategic problem. Furthermore, the algorithm is competitive with a metaheuristic published for the case of uncapacitated depots. 相似文献
45.
Behaviour of plasmalogens during high-performance liquid chromatography on a silica column with a mobile phase containing phosphoric acid 总被引:1,自引:0,他引:1
Silica high-performance liquid chromatographic separation of phospho- and sphingolipids of biological origin using a mobile phase containing phosphoric acid leads to gradual hydrolysis of plasmalogens during their passage through the column. The resulting 2-acyl lyso analogues give rise to peaks that tail in the direction of the parent intact plasmalogen. Tailing can be prevented by previous complete acid hydrolysis of plasmalogens. Direct high-performance liquid chromatographic profiling of phospholipids, their plasmalogens (as 2-acyl lyso analogues) and sphingolipids is probably the method of choice for the diagnosis of patients with deficient plasmalogen biosynthesis caused by peroxisomal abnormalities. 相似文献
46.
In the research for a selective extractant for nickel a strained dioxime, β-nopinoquinone dioxime, has been studied in its extraction properties for copper(II) and nickel(II). Spectroscopic investigations (ESR and NMR) showed that both copper and nickel are extracted as a N,N-coordinated chelate. The extraction studies showed that the use of strained instead of aliphatic dioximes makes the extraction more convenient because of the higher extraction rate, but the selectivity for nickel above copper disappears.δ-nopinoquinone dioxime is easily converted into its furazan by treatment with 1N NaOH. This furazan is a rather weak ligand without significant extraction capacities. 相似文献
47.
48.
Dissipative Synthetic DNA‐Based Receptors for the Transient Loading and Release of Molecular Cargo
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Dr. Giulio Ragazzon Prof. Leonard J. Prins Prof. Francesco Ricci 《Angewandte Chemie (International ed. in English)》2018,57(33):10489-10493
Supramolecular chemistry is moving into a direction in which the composition of a chemical equilibrium is no longer determined by thermodynamics but by the efficiency with which kinetic states can be populated by energy consuming processes. Herein, we show that DNA is ideally suited for programming chemically fueled dissipative self‐assembly processes. Advantages of the DNA‐based systems presented in this study include a perfect control over the activation site for the chemical fuel in terms of selectivity and affinity, highly selective fuel consumption that occurs exclusively in the activated complex, and a high tolerance for the presence of waste products. Finally, it is shown that chemical fuels can be used to selectively activate different functions in a system of higher complexity embedded with multiple response pathways. 相似文献
49.
Dr. Flavio della Sala Dr. Subhabrata Maiti Andrea Bonanni Prof. Dr. Paolo Scrimin Prof. Dr. Leonard J. Prins 《Angewandte Chemie (International ed. in English)》2018,57(6):1611-1615
The transient activation of function using chemical fuels is common in nature, but much less in synthetic systems. Progress towards the development of systems with a complexity similar to that of natural ones requires chemical fuel selectivity. Here, we show that a self‐assembled nanosystem, composed of monolayer‐protected gold nanoparticles and a fluorogenic peptide, is activated for transient signal generation only in case the chemical fuel matches the recognition site present at the nanoparticle surface. A modification of the recognition site in the nanosystem completely changes the chemical fuel selectivity. When two nanosystems are simultaneously present, the selectivity expressed by the system depends on the concentration of nucleotide added. 相似文献
50.
Tshakane Tshepe Johan F. Prins Michael J. R. Hoch 《Czechoslovak Journal of Physics》1996,46(5):2441-2442
Experimental data for the conductivity of type IIa diamond specimens implanted at low temperatures with carbon ions, followed by high temperature annealing, have been analyzed using hopping and percolation theories in the vicinity of the insulator-metal transition. Near the transition it appears that conductivity occurs viasp 2-bonded graphitic clusters which are randomly distributed in thesp 3-bonded diamond matrix. A conductivity crossover between the Mott and Efros-Shklovskii VRH laws has been observed on the insulating side of the transition. 相似文献