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991.
In this paper, flexible job shop scheduling problem with a new approach, overlapping in operations, is discussed. In many flexible job shops, a customer demand can be released more than one for each job, where demand determines the quantity of each finished job ordered by a customer. In these models each job has a demand more than one. This assumption is an important and practical issue for many flexible job shops such as petrochemical industries. To consider this assumption, we use a new approach, named overlapping in operations. In this approach, embedded operations of each job can be performed due to overlap considerations in which each operation may be overlapped with the others because of its nature. The overlapping is limited by structural constraints, such as the dimensions of the box to be packed or the capacity of the container used to move the pieces from one machine to the next. Since this problem is well known as NP-Hard class, a hierarchical approach used simulated annealing algorithm is developed to solve large problem instances. Moreover, a mixed integer linear programming (MILP) method is presented. To evaluate the validity of the proposed SA algorithm, the results are compared with the optimal solution obtained with the traditional optimization technique (The Branch and Bound method). The computational results validate the efficiency and effectiveness of the proposed algorithm. Also the computational results show that the overlapping considering can improve the makespan and machines utilization measures. So the proposed algorithm can be applied easily in real factory conditions and for the large size problems and it should thus be useful to both practitioners and researchers. 相似文献
992.
Matthias Linnert 《Journal of organometallic chemistry》2006,691(11):2358-2367
Sulfones RCH(R′)SO2Ph were reacted with n-BuLi in thf/n-hexane (R/R′ = H/Me, Me/Et, H/CH2Ph) and toluene/n-hexane (R/R′ = Me/Ph) yielding under deprotonation Li[CR(R′)SO2Ph] which reacted with Me3SiCl and n-Bu3SnCl forming the requisite trimethylsilyl and tri(n-butyl)tin substituted derivatives . Performing the reactions of RCH(R′)SO2Ph with n-BuLi in n-hexane (instead of thf/n-hexane) and toluene/n-hexane, respectively, resulted in the precipitation of the organo lithium compounds Li[CR(R′)SO2Ph] (1-4) which were isolated as strongly moisture-sensitive yellow powders in essentially quantitative yields. Their identities were confirmed by 1H and 13C NMR spectroscopic measurements in thf-d8. Solutions of each 1, 3, and 4 in thf/n-hexane and thf/n-pentane afforded crystals of each [{Li{CH(Me)SO2Ph}(thf)}∞] (1a), [{Li{CH(CH2Ph)SO2Ph}(thf)}∞] (3a), and [{Li{CMe(Ph)SO2Ph}(thf)2}2] (4a), respectively, whose structures were determined by single-crystal X-ray crystallography. The compounds 1a and 3a crystallize in 1D polymeric ladder-like structures. The strands of 1a are built-up by eight-membered Li2C2S2O2 rings having direct Li-C bonding interactions (Li-C 2.215(5) Å). The donor set of Li is completed by three oxygen atoms, one from the thf ligand and two from SO2 groups of neighboring Li{CH(Me)SO2Ph}(thf) entities. The strands of 3a are built-up of alternating Li2S2O4 eight- and Li2O2 four-membered rings. Each lithium atom is coordinated to three oxygen atoms, two from O2S(Ph)CHCH2Ph groups and one from thf oxygen atom. There is no Li-C bonding. Compound 4a crystallizes in dimers consisting of eight-membered Li2S2O4 rings in which the two lithium atoms are bridged by two O2S(Ph)CHMePh groups. The coordination sphere of lithium is completed by two oxygen atoms of the thf ligands. 相似文献
993.
Defne Bayraktar Stefan Diethelm Peter Holtappels Thomas Graule Jan Van herle 《Journal of Solid State Electrochemistry》2006,10(8):589-596
The influence of partial substitution of Fe with Ti on the oxygen transport properties of La1−x
Sr
x
FeO3 membranes was investigated in view of their application for oxygen separation. Samples of composition (y=0, 0.2) were prepared and their oxygen transport properties characterised by potential step relaxation and by oxygen permeation
measurement in an air/argon gradient. With the first technique, chemical diffusion and surface exchange (k
S) coefficients were obtained by fitting of the current relaxation data to a single expression valid over the complete time
range. The Ti-substituted composition gave slightly larger values of and k
S. The trend was opposite for the measured oxygen permeation flux. In the latter experience, ordering of oxygen vacancies was
observed at lower temperature, reducing significantly the performance of the material. 相似文献
994.
A reactor module, consisting of six gas-tight hollow fibre membranes made of the mixed ionic–electronic conducting perovskite,
, has been tested for oxygen permeation and stability during methane oxidation in the temperature range of 540 to 960°C. Rigorous
leak testing was undertaken and it was demonstrated that the module could be adequately sealed. Oxygen permeation fluxes were
similar to those reported by previous workers. At higher temperatures of operation, it appeared that mass transfer limited
the oxygen flux, as this flux was dependent upon the flow rates on either side of the membrane. In this way, reactant flow
rates could be used to manipulate the transmembrane oxygen flux. It was found that the product distribution on the methane
side was dependent upon this flux, with carbon monoxide and hydrogen production being favoured at low fluxes and carbon dioxide
and water production being favoured at higher fluxes. Furthermore, at low oxygen flow rates, periodic increases in the transmembrane
oxygen flux were observed. The cause of this behaviour is unclear but may be as a result of phase/stoichiometric changes associated
with the membrane material. 相似文献
995.
Xiong Yin Catherine Choong Liang Hong Zhaolin Liu 《Journal of Solid State Electrochemistry》2006,10(8):643-650
This work reports a new design of asymmetric tubular oxygen-permeable ceramic membrane (OPCM) consisting of a porous Y2O3 stabilized ZrO2 (YSZ) tube (with ∼1 μm of pore diameters and 31% porosity) as the support and a gas-tight mixed conductive membrane. The
membrane has an interlocking structure composed of a host matrix, Ag(Pd) alloy (9:1 by wt) doped perovskite-type (LSM80, 90wt%), and the embedded constituent, pristine LSM80. The Ag(Pd) alloy component promotes not only electronic conductivity
and mechanical strength but also reduction of both porosity and pore sizes in the layer (∼10-μm-thick) where it dopes. The
porous structure in this layer could then be closed through a solution coating procedure by which ingress of an aqueous solution
containing stoichiometric nitrate salts of La3+, Mn3+, and Sr2+ to the pore channels takes place first and the mixture of nitrate salts left after drying is subjected to pyrolysis to generate
tri-metal oxides in situ. This is followed by calcinations at l,300 °C to consolidate the embedded trioxide and to cohere
them with the Ag(Pd)-LSM80 host matrix. The structure formed is dubbed LSM80(S)-Ag(Pd)-LSM80, which was confirmed gas-tight
by electron micrograph and N2 permeation test. Finally, we assess the chemical compatibility between LSM80 and YSZ at the sintering temperature by X-ray
diffraction and electrochemical impedance analysis. The oxygen permeation of the fabricated LSM80(S)-Ag(Pd)-LSM80-YSZ membrane
is within the temperature range of 600 to 900 °C. The tests reveal good compatibility between the LSM80 and YSZ and a reasonably
high oxygen permeation flux in association with this OPCM assembly. 相似文献
996.
Pasic A Koehler H Schaupp L Pieber TR Klimant I 《Analytical and bioanalytical chemistry》2006,386(5):1293-1302
A new microdialysis-based glucose-sensing system with an integrated fiber-optic hybrid sensor is presented. Design and dimensions
of the cell are adapted for its coupling with commercially available microdialysis techniques, thereby providing a new system
for continuous glucose monitoring. The glucose level is detected via oxygen consumption which occurs as a consequence of enzymatic
reaction between immobilized glucose oxidase and glucose. The use of gas-permeable Tygon tubing ensures complete and constant
air-saturation of the measuring fluid in the cell. Nevertheless, a reference oxygen optode is used to detect and to compensate
response changes caused by events like bacterial growth, temperature fluctuations, or failure of the peristaltic pump. In
contrast to widely used electrochemical sensors, the response of the microdialysis-based fiber-optic glucose sensor is highly
selective, making this sensor approach particularly advantageous for continuous glucose monitoring of patients in intensive
care units. The effects of flow rate, pH, temperature, and common interferences on the sensor response are presented and discussed
in detail. The sensor is evaluated in vitro using a 3-day continuous test in glucose-spiked plasma. The ability to measure
glucose in humans is demonstrated by coupling the flow-through cell and commercially available microdialysis catheter CMA60.
A 24-h monitoring test using this setup is successfully applied to a healthy volunteer. 相似文献
997.
The geometry and the vibrational properties of missing row reconstructed O/Cu(0 0 1) and O/Ag(0 0 1) surfaces are investigated by means of density functional theory and density functional perturbation theory, using the local density and the generalized-gradient approximations. Our results predict very similar structural and vibrational properties for the two reconstructed surfaces. In the case of copper our calculations reproduce quite accurately the experimental results, while for the missing row reconstructed O/Ag(0 0 1) surface the agreement between theory and experiment is less satisfactory. 相似文献
998.
999.
Tetsuya Kida Atsunori Yamasaki Noboru Yamazoe 《Journal of solid state chemistry》2010,183(10):2426-2431
We carried out the partial substitution of the B-site in BaFeO3−δ perovskite with divalent cations to develop novel oxygen-permeable materials. We demonstrated that the partial substitution of Cu or Ni by more than 10% resulted in the stabilization of the cubic perovskite structure even at room temperature in a highly oxygen-permeable phase, as revealed by the X-ray diffraction (XRD) analysis. The Cu substitution was more effective for the stabilization, because the introduction of Cu in the lattice more effectively made the Goldschmidt tolerance factor (t) close to 1.0. Ni- and Cu-substituted BaFeO3−δ membranes showed higher oxygen permeabilities than their parent BaFeO3−δ membranes particularly at lower temperatures around 600-700 °C owing to the stabilization of the cubic phase. Among the fabricated membranes, a BaFe0.85Cu0.15O3−δ membrane (1.0 mm thickness) showed the highest oxygen permeation flux (1.8 cm3 min−1 cm−2 at 930 °C) under an air/He gradient. The results indicated that Cu-substituted BaFeO3-δ is promising as a material for Co-free membranes with high oxygen permeabilities. 相似文献
1000.
Hyo Sung Kim Ju Chan Yang Yong Sung Koo Hyoun Woo Kim 《Journal of solid state chemistry》2010,183(10):2445-2450
Nanowires consisting of GaN/Mn3O4 were prepared using a two-step approach that involved dipping the as-synthesized GaN nanowires into an aqueous manganese acetate solution. To examine the effects of annealing, GaN/Mn3O4 core-shell nanowires were heated thermally to 700 °C in N2 ambient. Transmission electron microscopy showed that the continuous Mn3O4 shell layer had agglomerated to expose a bare GaN core surface after thermal annealing. The magnetic measurements showed that the ferromagnetic behavior of the GaN nanowires had been suppressed by coating with the Mn3O4 shell, without significant change by the subsequent thermal annealing. The GaN/Mn3O4 core-shell nanowires exhibited blue, green, and red photoluminescence (PL) emission. The red emission was enhanced by thermal annealing. This paper discusses the associated mechanism for the variations in PL and magnetic properties of GaN/Mn3O4 core-shell nanowires. 相似文献